TWM604378U - Power supply for lamp string - Google Patents

Abstract

A power supply for light strings includes a cable, a switching circuit, and a transformer. The cable has a receiving end and a load end, and the cable has at least two wires, respectively extending from the receiving end to the load end. The switching circuit is connected across the two wires to selectively form a voltage divider between the two wires. The transformer includes a transformer circuit and a control circuit. The transformer circuit has an input terminal and an output terminal. The transformer routing input terminal receives an external power and converts it into a driving power, outputs the driving power through the output terminal, and the receiving terminal of the cable is electrically connected to the output terminal. The control circuit is electrically connected to the transformer circuit and the two wires; the control circuit detects the voltage division state between the two wires, and sends a switching signal to the transformer circuit to change the driving power according to the voltage division state.

Description

Power supply for light string

The present invention relates to a transformer, especially a transformer for light strings.

The light string is a long linear lighting device formed by multiple light-emitting diodes connected in series, parallel or mixed series/parallel.

The light string is driven by the PWM power provided by the transformer. Through the adjustment of output voltage, frequency, and duty cycle, the brightness and flicker changes of the light-emitting diodes in the light string can be changed.

As shown in Figure 1, most of the existing transformers are integrated into a single plug type, which is directly plugged into a household AC outlet, and the control circuit is also provided at the transformer end, for example, US 9,781,781B2 new patent. In the aforementioned transformer containing the control circuit, the control circuit and the transformation circuit are both installed in the housing of the transformer; the switch is welded and fixed to the circuit board and exposed through the hole of the housing; the seal is covered on the hole to perform the switch seal. By pressing the switch, the control circuit switches the output of the transformer circuit and outputs the corresponding PWM power to the load end. In the aforementioned transformers, the buttons are integrated into a single-plug type transformer, so that the setting positions of the function buttons are restricted. When the user operates the transformer to switch, he must operate at the household AC outlet, which is prone to electric shock. In addition, a single plug type transformer is not easy to be designed for waterproofing. For example, US 9,781,781B2 uses a sealing element to cover the opening, but the sealing element also needs to be repeatedly pressed and easily damaged. That is to say, once the damp state occurs, the transformer is prone to leakage, and the user is prone to electric shocks during switching operations.

As shown in Figure 2, another design is to separately set the control circuit and buttons in another shell to form an independent controller, and set the controller in the middle of the cable or at any position. However, under this structure, in addition to the original conductive wires for transmitting power, additional control signal wires are required to transmit the control signals of the control circuit to the transformer circuit, which makes the overall wiring complicated.

Based on the above problems, the present invention proposes a power supply for light strings, which is used to change the switching operation mode.

At least one embodiment of the present invention provides a power supply for a light string, which includes a cable, a switching circuit, and a transformer. The cable has a receiving end and a load end, and the cable has at least two wires, respectively extending from the receiving end to the load end. The switching circuit is connected across the two wires to selectively form a voltage divider between the two wires. The transformer includes a transformer circuit and a control circuit. The transformer circuit has an input terminal and an output terminal. The transformer routing input terminal receives an external power and converts it into a driving power, outputs the driving power through the output terminal, and the receiving terminal of the cable is electrically connected to the output terminal. The control circuit is electrically connected to the transformer circuit and the two wires; the control circuit detects the voltage division state between the two wires, and sends a switching signal to the transformer circuit to change the driving power according to the voltage division state.

In at least one embodiment, the transformer further includes a housing and at least two metal sheets. The transformer circuit and the control circuit are arranged in the housing, and the metal sheets protrude from the surface of the housing and are connected to the input terminal.

In at least one embodiment, the switching circuit is a normally open contact switch, and a voltage divider resistor is provided between the normally open contact switch and one of the wires.

In at least one embodiment, the switching circuit has an encoder, a plurality of normally open contact switches, and a switch chip; the normally open contact switch is connected to the encoder for being pressed to generate a corresponding selection signal, and each normally The open contact switches respectively correspond to a trigger signal combination; each normally open contact switch drives the encoder to generate a corresponding switch signal with the corresponding trigger signal combination, and the drive switch chip drives the switch signal to connect two wires to form a voltage divider. Form a corresponding trigger signal combination; and the control circuit has a power management chip, a switching controller and a decoder; the switching controller is electrically connected to the power management chip and the decoder, and the power management chip obtains working power; the decoder Connected to the two wires, and the decoder is used to analyze each trigger signal combination and send corresponding information to the switching controller, so that the switching controller sends a switching signal to the transformer circuit to change the driving power according to each trigger signal combination.

In at least one embodiment, the control circuit further includes a remote control signal receiver connected to the switching controller; the remote control signal receiver is used to receive a plurality of remote control selection signals and transmit them to the switching controller; each remote control selection signal corresponds to a switching mode , So that the switching controller sends a switching signal to the transformer circuit to change the driving power.

In at least one embodiment, the transformer circuit has a converter corresponding to the input terminal configuration for converting external power into DC power, and the power management chip is electrically connected to the converter to perform step-up and step-down of the DC power. Output driving power.

In at least one embodiment, at every sampling time point, the power management chip switches the driving power voltage to a sampling voltage for a detection time, and the decoder performs one or more detections within the detection time to determine whether there is The partial pressure state is generated and the trigger signal combination is analyzed.

In at least one embodiment, the switching circuit is composed of a plurality of normally open contact switches, and each normally open contact switch is connected to two wires through a voltage divider resistor, and the resistance value of each voltage divider resistor is different, so that each When the normally open contact switch is pressed, different voltage divisions are formed; and the control circuit has a power management chip, a switching controller and a voltage detection unit; the switching controller is electrically connected to the power management chip and the voltage detection unit, And the working power is obtained by the power management chip; the voltage detection unit is connected to the two wires, and the voltage detection unit is used to detect the voltage division between the two wires, and output a detection result to the switching controller, so that the switching controller can follow The detection result determines the pressed normally open contact switch, and sends a switching signal to the transformer circuit to change the driving power.

In at least one embodiment, at every sampling time point, the power management chip switches the voltage of the driving power to a sampling voltage for a detection time, and the voltage detection unit performs one or more voltage detections within the detection time. Determine whether the voltage difference between the two wires is lower than the sampling voltage, and output the detection result according to an actual voltage change.

In the present invention, the position of the switching circuit is moved to the cable line and separated from the transformer. Therefore, the user does not need to operate on the transformer to switch the output of the transformer, avoiding the danger of high-voltage electric shock. At the same time, the switching circuit can be easily provided with waterproof measures, such as being covered with plastic film or waterproof glue, to reduce the risk of leakage of the switching circuit due to moisture. In addition, because the normally open contact switch of the switching circuit is arranged on the cable line, the normally open contact switch can be set at any position on the cable line according to the design requirements of the light string product to realize the demand for product diversification.

1: power supply

100: Cable

101: receiving end

102: load side

112: Wire

200: switching circuit

220: encoder

300: Transformer

310: Transformer circuit

311: Input

312: output

313: Inverter

314: power management chip

320: control circuit

322: switch controller

324: Decoder

325: Remote control signal receiver

326: Voltage detection unit

331: Shell

332: metal sheet

400: light string

500: Christmas tree

600: Remote control signal transmitter

R: resistance

R1, R2: voltage divider resistor

REG: voltage regulator

CTRL: Switch chip

K1, K2, K3: normally open contact switch

Vcc: working power

Ve: external power

Vout: drive power

Fig. 1 is a schematic diagram of a power supply for a light string in the prior art.

Fig. 2 is a schematic diagram of a power supply of another light string in the prior art.

FIG. 3 is a circuit block diagram of the power supply of the light string disclosed in the first embodiment of the new type.

4 is another circuit block diagram of the power supply for the light string disclosed in the first embodiment of the new type.

5 is a schematic diagram of the power supply of the light string disclosed in the first embodiment of the new type.

FIG. 6 is a schematic diagram of the use state of the power supply of the light string in the first embodiment of the new type.

FIG. 7 is a circuit block diagram of a power supply for a light string disclosed in the second embodiment of the present invention.

FIG. 8 is another circuit block diagram of the power supply of the light string disclosed in the second embodiment of the present invention.

Figures 9 and 10 are schematic diagrams of the time for performing detection on the two wires in the second embodiment of the present invention.

FIG. 11 is a circuit block diagram of a power supply for a light string disclosed in the third embodiment of the new type.

FIG. 12 is a circuit block diagram of a power supply for a light string disclosed in the fourth embodiment of the present invention.

FIG. 13 is another circuit block diagram of the power supply of the light string disclosed in the fourth embodiment of the present invention.

Fig. 14 is a schematic diagram of the time for detecting two wires in the fourth embodiment of the new type.

Please refer to FIG. 3 and FIG. 4, which is a power supply 1 for a light string 400 disclosed in the first embodiment of the present invention, which includes a cable 100, a switching circuit 200, and a transformer 300.

As shown in FIGS. 3 and 4, the cable 100 has a receiving end 101 and a load end 102, and the cable 100 has at least two wires 112 extending from the receiving end 101 to the load end 102, respectively. The load terminal 102 is used to connect to the light string 400; wherein, the load terminal 102 can be directly connected to the light string 400 by welding, or can be connected to the light string 400 through a combination of electrical connectors. Or, the second wire 112 may be a part of the light string 400, and the load terminal 102 corresponds to a section of the light emitting diode. The switching circuit 200 is connected across the two wires 112 for selectively connecting the two wires 112 to generate voltage division.

As shown in FIGS. 3 and 4, the transformer 300 includes a transformer circuit 310 and a control circuit 320. The transformer circuit 310 has an input terminal 311 and an output terminal 312. The transformer circuit 310 receives an external power Ve from the input terminal 311 and converts it into a driving power Vout, and the transformer circuit 310 outputs the driving power Vout through the output terminal 312. The receiving end 101 of the cable 100 is electrically connected to the output end 312 and can output the driving power Vout to the load end 102.

As shown in FIG. 3, the control circuit 320 is electrically connected to the transformer circuit 310 and the two wires 112. The control circuit 320 detects the voltage division state between the two wires 112 and sends a switching signal to the transformer circuit 310 to change the driving power Vout according to the voltage division state.

As shown in FIGS. 3 and 4, the transformer 300 further includes a housing 331 and two or more metal sheets 332. The transformer circuit 310 and the control circuit 320 are disposed in the housing 331, and the metal sheet 332 protrudes from the surface of the housing 331 and is connected to the input terminal 311. Specifically, the metal piece 332 is the pin of the AC power plug and can be inserted into the AC power socket to receive household AC power as the external power Vc.

The driving power Vout may be a pulse width modulation signal (Pulse Width Modulation, PWM) for driving the light string 400 to emit light. The control circuit 320 is used to control the The voltage circuit 310 changes the frequency, bandwidth, and PWM duty cycle of the driving power Vout, so as to adjust the average current output by the voltage transformer circuit 310 and adjust the brightness of the light string 400.

As shown in FIG. 4, in the first embodiment, the specific solution of the switching circuit 200 is a normally open contact switch, such as a micro switch, a capacitor switch or a membrane switch, and the normally open contact switch is provided between one of the wires 112 A voltage divider resistor R with a high resistance value for voltage divider control. Therefore, the normally open contact switch can cause a voltage division between the two wires 112 when pressed.

In the present invention, the control circuit 320 periodically detects the voltage division state between the two wires 112 in sections. When the voltage of the two wires 112 is stepped down and the voltage is divided across the voltage divider resistor R, it is regarded as receiving a trigger signal. The trigger number and duration of the trigger signal can form a coded trigger signal combination, which enables the control circuit 320 to send a switching signal to the transformer circuit 310 to change the frequency, voltage and PWM duty cycle of the driving power Vout to adjust the light string The brightness of the 400 light or the flicker frequency. For example, a short press increases the brightness of the light string 400, while a long press reduces the brightness of the light string 400, a long press and a short press to switch the light string 400 to blink, and two long presses to switch the light string 400 to not blink, etc.

As shown in FIGS. 5 and 6, in the present invention, the position of the switching circuit 200 is moved to the cable line 100 and separated from the transformer 300. Therefore, the user does not need to operate on the transformer 300 to switch the output of the transformer 300 to avoid the danger of high voltage electric shock. In addition, taking a normally open contact switch as an example, there may be multiple switching circuits 200, for example, three normally open contact switches K1, K2, and K3 are respectively arranged in different positions. At the same time, the voltage divider resistors R1, R2, and R3 connected to the three normally open contact switches K1, K2, and K3 are not necessarily the same, but may have different resistance values. In other words, when different normally open contact switches K1, K2, K3 are pressed, the divided voltages generated are also different, and the control circuit 320 can directly switch the driving power Vout according to the different divided voltage states, without requiring multiple times Press A single normally open contact switch forms a code. For example, press K1 to increase the brightness of the light string 400, press K2 to decrease the brightness of the light string 400, and press K3 to turn on or off the light string 400. In addition, different normally open contact switches K1, K2, K3 can also be configured in different positions of the cable 100 according to their function design; for example, when the light string 400 is used to decorate the Christmas tree 500, the normally open contact switch of the switching circuit 200 K1, K2, and K3 can be arranged on the Christmas tree 500, the trunk or hanging on the leaves or the middle section of the cable 100; at this time, the user can directly switch on the Christmas tree 500.

Please refer to FIG. 7 and FIG. 8, which is a power supply 1 for a light string 400 disclosed in the second embodiment of the present invention, which includes a cable 100, a switching circuit 200 and a transformer 300. In the first embodiment, in the switching circuit 200, the user manually presses the normally open contact switch to generate a trigger signal combination. In the second embodiment, the switching circuit 200 can automatically generate a relatively complex combination of trigger signals.

As shown in FIG. 4, the switching circuit 200 has an encoder 220, a voltage regulator REG, a plurality of normally open contact switches K1, K2, K3, and a switch chip CTRL. The voltage regulator REG is connected to the two wires 112 to obtain the driving power Vout and convert it into the working power Vcc, which is provided to the encoder 220 as the working power Vcc. The switch chip CTRL is connected to the two wires 112, and the switch chip CTRL is used to receive the switch signal and connect the two wires 112 through the voltage dividing resistor R to generate a voltage division according to the switch signal. A plurality of trigger signal combinations are set in the encoder 220, and switch signals of each combination are generated to drive the switch chip CTRL through the voltage divider resistor R to connect the two wires 112 to generate a voltage division according to the switch signal to form a trigger signal combination.

As shown in Figure 7, normally open contact switches K1, K2, K3 are connected to the encoder 220, and are used to generate selection signals when pressed. Each normally open contact switch K1, K2, K3 corresponds to a trigger Signal combination. Therefore, for the needs of turning on, turning off or switching the light string 400, the user only needs to press the corresponding normally open contact switches K1, K2, K3 to drive the encoder 220 to generate the corresponding switch signal with the corresponding trigger signal combination. The driving switch chip CTRL drives the two wires 112 through the voltage divider resistor R to generate a voltage division according to the switch signal to form a trigger signal combination. The normally open contact switches K1, K2, K3 can be micro switches, capacitor switches or membrane switches. One end is connected to the encoder 220, and the other end is grounded. The corresponding contact of the encoder 220 can be changed from high level when pressed For the low level, it forms a selection signal.

As shown in FIG. 8, the transformer circuit 310 has an inverter 313 and a power management chip 314 (Power IC). The inverter 313 can be a winding group or a bridge rectifier circuit. The inverter 313 is configured corresponding to the input terminal 311 and is used to convert household AC power, which is the external power Ve, into DC power. The power management chip 314 is electrically connected to the inverter 313 and is configured corresponding to the output terminal 312. The power management chip 314 is used as a power switch and DC power up and down to output driving power Vout.

As shown in FIG. 8, the control circuit 320 has a switching controller 322 and a decoder 324. The decoder 324 is connected to the two wires 112, the switching controller 322 is electrically connected to the power management chip 314 and the decoder 324, and the inverter 313 obtains the operating power Vcc.

The decoder 324 is used to analyze the trigger signal combination and send corresponding information to the switching controller 322 so that the switching controller 322 loads the corresponding switching mode according to the trigger signal combination. According to the switching mode, the switching controller 322 sends a switching signal to the transformer circuit 310 to change the frequency, bandwidth, or voltage of the driving power Vout, and adjust the brightness or blinking frequency of the light string 400. For example, pressing the normally open contact switch K1 can increase the brightness of the light string 400, while pressing the normally open contact switch K2 can switch the light string 400 to blinking, and pressing the normally open contact switch K3 can switch the light. String 400 means no flicker, etc. The number of normally open contact switches K1, K2, K3 is not limited to three, and can be three or more or less than three. In the second embodiment, the operation of connecting the two wires 112 through the voltage dividing resistor R is performed by the encoder 220 driving the switch chip CTRL, and the time for each detection of the divided voltage state can be greatly shortened. Therefore, the human eye will not be able to recognize the detection component. The light string 400 is briefly extinguished when it is under pressure. In addition, the transformer circuit 310 and the switching circuit 200 of the second embodiment can also be applied to the first embodiment.

As shown in Figure 9, the actual detection of the partial pressure state is described as follows. Assuming that the driving power Vout is used to drive the light string 400 at 12V, the switching controller 322 first controls the power management chip 314 to output the driving power Vout at 12V after starting, so that the light string 400 is lit. At every sampling time point, for example, 0.3 seconds later, the power management chip 314 switches the driving power Vout to a sampling voltage Vs, for example, drops to 5V, and continues for a detection time, for example, 0.015 seconds. The sampling voltage Vs is set to a voltage value that cannot drive the light string 400 to emit light, so that the light string 400 is temporarily extinguished. At this time, the decoder 324 performs one or more detections within the detection time. For example, after entering the detection time of 0.01 seconds, it performs a detection every 0.0005 seconds for 10 times, determines whether there is a partial pressure state, and analyzes the trigger signal combination. The sampling voltage Vs is usually set to a low voltage value that cannot drive the light string 400 to emit light, so as to avoid excessive current during detection. Although the light string 400 will be extinguished during the detection time, the detection time is extremely short and the sampling time point is set at a high frequency, and the human eyes cannot observe the light string 400 being temporarily extinguished.

As shown in Figure 10, similarly, one of the normally open contact switches K1, K2, K3 can be set as a power switch. When the light string 400 is turned on, the corresponding trigger signal combination can be used as a turn-off signal, so that the switching controller 322 controls the power management chip 314 to reduce the driving power Vout to be lower than the start voltage of the light-emitting diode and the light string 400 cannot be lighted. 5V sampling voltage Vs, so that The light string 400 is turned off. At this time, the transformer circuit 310 still outputs the operating power Vcc to the control circuit 320, so the decoder 324 can continue to detect the second wire 112, and when it detects that the combination corresponding to the trigger signal appears again, the switching controller 322 can be regarded as a start signal , Control the power management chip 314 to increase the driving power Vout to 12V.

Referring to FIG. 11, it is a transformer 300 proposed in the third embodiment of the present invention, which can be used to replace the transformer 300 of the foregoing embodiments. In the third embodiment, the control circuit 320 further includes a remote control signal receiver 325 connected to the switching controller 322. The remote control signal receiver 325 is used to receive a plurality of remote control selection signals from the remote control signal transmitter 600 and transmit them to the switching controller 322. Each remote control selection signal corresponds to a switching mode, so that the switching controller 322 sends a switching signal to the transformer circuit 310 to change the frequency, bandwidth, or voltage of the driving power Vout, and adjust the brightness or blinking frequency of the light string 400.

As shown in FIGS. 12 and 13, a power supply 1 for a light string 400 disclosed in the fourth embodiment of the present invention includes a cable 100, a switching circuit 200 and a transformer 300.

As shown in FIG. 12, in the fourth embodiment, the switching circuit 200 is simplified to consist of a plurality of normally open contact switches K1, K2, K3, and each normally open contact switch K1, K2, K3 passes through a divided voltage The resistors R1, R2, and R3 are connected across the two wires 112, and each of the voltage dividing resistors R1, R2, and R3 has a different resistance value to form different voltage divisions when the normally open contact switches K1, K2, and K3 are pressed.

As shown in FIG. 13, the control circuit 320 is roughly the same as the second and third embodiments, except that the decoder 324 is replaced with a voltage detection unit 326. The voltage detection unit 326 is connected to the two wires 112, the switching controller 322 is electrically connected to the power management chip 314 and the voltage detection unit 326, and the inverter 313 obtains the working power Vcc.

As shown in Figure 13 and Figure 14, the normally open contact switches K1, K2, and K3 are connected to different voltage divider resistors R1, R2, R3, and can pass through the divider when the normally open contact switches K1, K2, K3 are pressed. Piezoresistors R1, R2, and R3 form different partial pressures. The voltage detection unit 326 can detect the divided voltage and send corresponding information to the switching controller 322, so that the switching controller 322 judges the pressed normally open contact switch K1, K2, K3 according to the detection result and loads the corresponding switching mode . The voltage detection unit 326 may be a comparator, which compares the voltage between the two wires 112 into which range, and outputs the corresponding detection result, so that the switching controller 322 can determine the normally open contact switch that is pressed according to the detection result K1, K2, K3. Alternatively, the voltage detection unit 326 may also be an analog-digital conversion chip, which converts the voltage value into a digital signal and transmits it to the switching controller 322, so that the switching controller 322 determines the pressed normally open contact switches K1, K2 according to the voltage value. K3.

According to the switching mode, the switching controller 322 sends a switching signal to the transformer circuit 310 to change the frequency, voltage, and PWM duty cycle of the driving power Vout to adjust the brightness or blinking frequency of the light string 400. Therefore, by connecting the normally open contact switches K1, K2, K3 to the voltage divider resistors R1, R2, R3 with different resistance values, the control circuit 320 can distinguish different normally open contact switches K1, K2, K3, and realize Multi-button switching.

Refer to Figure 14 for the actual detection of the partial pressure state. Assuming that the driving power Vout is used to drive the light string 400 at 12V, the switching controller 322 first controls the power management chip 314 to output the driving power Vout at 12V to light the light string 400 after activation. At every sampling time point, for example, 0.3 seconds later, the power management chip 314 switches the driving power Vout to a sampling voltage Vs, for example, drops to 5V, so that the light string 400 is temporarily extinguished and continues for a detection time, for example, 0.015 seconds . At this time, the voltage detection unit 326 performs one or more voltage comparisons within the detection time. For example, after entering the detection time 0.01 seconds, the voltage comparison is performed every 0.0005 seconds and the comparison is performed 10 times to determine the second lead Whether the voltage difference between the lines 112 is lower than the sampling voltage Vs, and the comparison result is output according to the actual voltage change. For example, the voltage divider resistor R1 reduces the voltage difference between the two wires 112 to 2.5V, and the voltage divider resistor R1 reduces the voltage difference between the two wires 112 to 3.5V. When 2.5V is detected, the output comparison result corresponds to the normally open contact switch K1 being pressed; when 333.5V is detected, the output comparison result corresponds to the normally open contact switch K2 being pressed. Similarly, the detection time is extremely short and the sampling time point is set at a high frequency, and human eyes cannot observe the short-term changes of the light string 400.

Similarly, as shown in Figure 10, one of the normally open contact switches K1, K2, K3 can be set as a power switch, and when the light string 400 is turned off, the driving power Vout drops below the start voltage of the light emitting diode. The 5V sampling voltage Vs of the light string 400 cannot be lighted, and the light string 400 is turned off. At this time, the transformer circuit 310 still outputs the operating power Vcc to the control circuit 320, so the voltage detection unit 326 and the switching controller 322 can continue to detect the two wires 112, and when the corresponding partial voltage is detected, the switching controller 322 can be regarded as a start signal, and the power management chip 314 is controlled to increase the driving power Vout to 12V to light up the light string 400.

In the present invention, the position of the switching circuit 200 is moved to the cable line 100 and separated from the transformer 300. Therefore, the user does not need to operate on the transformer 300 to switch the output of the transformer 300 to avoid the danger of high voltage electric shock. At the same time, the switching circuit 200 can be easily provided with waterproof measures, such as being covered with a plastic film or waterproof glue, to reduce the risk of leakage of the switching circuit 200 due to moisture. In addition, since the normally open contact switches K1, K2, and K3 of the switching circuit 200 are set on the cable line 100, the normally open contact switches K1, K2, K3 can be set on the cable line according to the design requirements of the light string 400 product Any position on the 100, realize the demand of product diversification.

1: power supply

100: Cable

101: receiving end

102: load side

112: Wire

200: switching circuit

300: Transformer

400: light string

Ve: external power

Vout: drive power

Claims (9)

A power supply for light strings includes: a cable with a receiving end and a load end, and the cable has at least two wires extending from the receiving end to the load end; a switching circuit, Connected to the two wires to selectively form a voltage divider between the two wires; and a transformer, including: a transformer circuit having an input terminal and an output terminal, and the transformer circuit receives a transformer from the input terminal The external power is converted into a driving power, the driving power is output through the output terminal, and the receiving end of the cable is electrically connected to the output terminal; and a control circuit is electrically connected to the transformer circuit and the two Wire; the control circuit detects the voltage division state between the two wires, and according to the voltage division state sends a switching signal to the transformer circuit to change the driving power. The power supply for light strings according to claim 1, wherein the transformer further includes a housing and at least two metal sheets, the transformer circuit and the control circuit are arranged in the housing, and the metal sheets protrude from the The surface of the housing and is connected to the input terminal. The power supply for light strings according to claim 1, wherein the switching circuit is a normally open contact switch, and a voltage divider resistor is provided between the normally open contact switch and one of the wires. The power supply for light strings according to claim 1, wherein: the switching circuit has an encoder, a plurality of normally open contact switches, a switch chip, and a voltage dividing resistor; the normally open contact switches Connected to the encoder, used to generate a corresponding selection when pressed Each of the normally open contact switches respectively corresponds to a trigger signal combination; each normally open contact switch drives the encoder to generate a corresponding switch signal with the corresponding trigger signal combination, and drives the switch chip to drive according to The switch signal is connected to the two wires through the voltage dividing resistor to generate a voltage division to form the corresponding trigger signal combination; and the control circuit has a power management chip, a switching controller and a decoder; the switching controller circuit Is connected to the power management chip and the decoder, and the power management chip obtains working power; the decoder is connected to the two wires, and the decoder is used to analyze each of the trigger signal combinations and send corresponding information to the switch The controller enables the switching controller to send a switching signal to the transformer circuit to change the driving power according to the combination of the trigger signals. The power supply for light strings according to claim 4, wherein: the control circuit further includes a remote control signal receiver connected to the switching controller; the remote control signal receiver is used to receive a plurality of remote control selection signals and transmit To the switching controller; each of the remote control selection signals corresponds to a switching mode, so that the switching controller sends the switching signal to the transformer circuit to change the driving power. The power supply for a light string according to claim 4, wherein the transformer circuit has an inverter corresponding to the input terminal configuration for converting the external power into direct current, and the power management The chip is electrically connected to the inverter to perform step-up and step-down of the DC power to output the driving power. The power supply for light strings according to claim 4, wherein, at every sampling time point, the power management chip switches the voltage of the driving power to a sampling voltage for a detection time, and the decoder Perform one or more detections within the detection time to determine whether there is a partial pressure state and analyze the trigger signal combination. The power supply for light strings according to claim 1, wherein: the switching circuit is composed of a plurality of normally open contact switches, each of the normally open contact switches is connected across two wires through a voltage divider resistor, And the resistance value of each of the voltage dividing resistors is different, so as to form different voltage divisions when each of the normally open contact switches is pressed; and the control circuit has a power management chip, a switching controller and a voltage detection unit; The switching controller is electrically connected to the power management chip and the voltage detection unit, and the power management chip obtains operating power; the voltage detection unit is connected to the two wires, and the voltage detection unit is used for detection The divided voltage between the two wires outputs a detection result to the switching controller, so that the switching controller determines the normally open contact switch that is pressed according to the detection result, and sends a switching signal to the change The voltage circuit changes the drive power. The power supply for light strings according to claim 8, wherein, at every sampling time point, the power management chip switches the voltage of the driving power to a sampling voltage for a detection time, the voltage detection unit Perform one or more voltage detections within the detection time to determine whether the voltage difference between the two wires is lower than the sampling voltage, and output the detection result according to an actual voltage change.

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