CN212677088U - Power supply for lamp string - Google Patents

Abstract

The utility model relates to a power supply for lamp string, which comprises a cable, a switching circuit and a transformer. The cable has a receiving end and a loading end, and the cable has at least two wires respectively extending from the receiving end to the loading end. The switching circuit is connected across the two conducting wires and used for selectively forming voltage division between the two conducting wires. The transformer comprises a transformation circuit and a control circuit. The voltage transformation circuit is provided with an input end and an output end, the voltage transformation circuit receives external power from the input end and converts the external power into driving power, the driving power is output through the output end, and the receiving end of the cable is electrically connected to the output end. The control circuit is electrically connected with the voltage transformation circuit and the two wires; the control circuit detects the voltage division state between the two wires and sends a switching signal to the voltage transformation circuit to change the driving power according to the voltage division state.

Description

Power supply for lamp string

Technical Field

The present invention relates to a transformer, and more particularly, to a transformer for a light string.

Background

The lamp string is a long-line shaped lighting device formed by connecting a plurality of light emitting diodes in series, in parallel or in a series/parallel mixed manner.

The light string is driven by PWM power supplied by a transformer, and the brightness, the flicker change and the like of the light emitting diode in the light string can be changed through the adjustment of output voltage, frequency and duty ratio.

As shown in fig. 1, most of the conventional transformers are integrated into a single plug type, and are directly plugged into a household ac socket, and a control circuit is also disposed at the transformer end, for example, in US 9,781,781B2 patent. In the transformer including the control circuit, the control circuit and the transforming circuit are both installed in a housing of the transformer; the switch is welded and fixed on the circuit board and is exposed through the hole of the shell; a seal covers the aperture to seal the switch. The control circuit switches the output of the voltage transformation circuit through the pressing of the switch, and outputs the corresponding PWM power to the load end. In the transformer, the buttons are all integrated in the transformer with a single plug type, so that the arrangement positions of the function buttons are limited, and when a user operates the transformer to switch, the user needs to operate the transformer beside a household alternating current socket, and the electric shock crisis is easy to occur. In addition, the single plug type transformer is not easy to be designed to be waterproof, for example, US 9,781,781B2 covers the opening with a sealing member, but the sealing member may be required to be pressed repeatedly and easily damaged. That is, once a wet state occurs, the transformer is prone to have a leakage condition, and a user is prone to receive an electric shock when performing a switching operation.

As shown in fig. 2, another design is to separately arrange the control circuit and the button in another housing to form a separate controller, and arrange the controller in the middle of the cable or at any position. However, in this structure, an extra control signal line is required in addition to the original conductive line for transmitting power, and the control signal of the control circuit is transmitted to the transformer circuit, so that the overall wiring becomes complicated.

Disclosure of Invention

In view of the above problems, the present invention provides a power supply for a string of lights, 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 loading end, and the cable has at least two wires respectively extending from the receiving end to the loading end. The switching circuit is connected across the two conducting wires and used for selectively forming voltage division between the two conducting wires. The transformer comprises a transformation circuit and a control circuit. The voltage transformation circuit is provided with an input end and an output end, the voltage transformation circuit receives external power from the input end and converts the external power into driving power, the driving power is output through the output end, and the receiving end of the cable is electrically connected to the output end. The control circuit is electrically connected with the voltage transformation circuit and the two wires; the control circuit detects the voltage division state between the two wires and sends a switching signal to the voltage transformation 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 disposed 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 dividing resistor is disposed between the normally open contact switch and the conductive line.

In at least one embodiment, 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 are connected with the encoder and used for being pressed to generate corresponding selection signals, and each normally open contact switch corresponds to one trigger signal combination; each normally open contact switch drives the encoder to generate a corresponding switch signal by each corresponding trigger signal combination, and the driving switch chip drives the encoder to form a partial voltage by connecting the two wires through the partial voltage resistor according to the switch signal so as to 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 with the power management chip and the decoder, and obtains working power from the power management chip; the decoder is connected with the two wires and used for analyzing each trigger signal combination and transmitting corresponding information to the switching controller, so that the switching controller sends out a switching signal to the voltage transformation circuit according to each trigger signal combination to change the driving power.

In at least one embodiment, the control circuit further comprises a remote control signal receiver connected to the switching controller; the remote control signal receiver is used for receiving a plurality of remote control selection signals and transmitting the remote control selection signals to the switching controller; each remote control selection signal corresponds to a switching mode, so that the switching controller sends out a switching signal to the transformer circuit to change the driving power.

In at least one embodiment, the transformer circuit further includes an inverter disposed corresponding to the input terminal for converting external power into dc power, and the power management chip is electrically connected to the inverter for stepping up and stepping down the dc power to output driving power.

In at least one embodiment, the power management chip switches the voltage of the driving power to the sampling voltage at every sampling time point and continues to detect the time, and the decoder performs one or more detections within the detection time to determine whether a voltage division state occurs and analyzes the trigger signal combination.

In at least one embodiment, the switching circuit comprises a plurality of normally open contact switches, each normally open contact switch is bridged with two wires through a voltage dividing resistor, and the resistance values of the voltage dividing resistors are different, so that different voltage division is formed when each normally open contact switch is pressed; the control circuit is provided with 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 obtains working power from the power management chip; the voltage detection unit is connected with the two leads and is used for detecting the partial pressure between the two leads and outputting a detection result to the switching controller, so that the switching controller judges the pressed normally open contact switch according to the detection result and sends a switching signal to the transformation circuit to change the driving power.

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

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 for switching the output of the transformer, and the danger of high-voltage electric shock is avoided. Meanwhile, the switching circuit can be easily provided with waterproof measures, such as coating with a plastic film or waterproof glue, so that the risk of electric leakage of the switching circuit due to dampness is reduced. In addition, because the normally open contact switch of switching circuit sets up on the cable conductor, consequently can be to the design demand of lamp cluster product, with the optional position of normally open contact switch setting on the cable conductor, realize the demand of product pluralism.

Drawings

FIG. 1 is a diagram of a power supply for a string of lights according to the prior art.

Fig. 2 is a schematic diagram of a power supply of a light string in the prior art, in which a control circuit and a button are separately disposed in another housing to form a separate controller.

FIG. 3 is a block diagram of a power supply of a light string according to a first embodiment of the present invention.

FIG. 4 is another block diagram of a power supply for a light string according to a first embodiment of the present invention.

FIG. 5 is a diagram of a power supply for a light string according to a first embodiment of the present invention.

FIG. 6 is a schematic diagram of a power supply of the light string according to the first embodiment of the present invention.

Fig. 7 is a block diagram of a power supply of a light string according to a second embodiment of the present invention.

FIG. 8 is another block diagram of a power supply for a light string according to a second embodiment of the present invention.

Fig. 9 and 10 are timing diagrams illustrating the detection of two wires according to the second embodiment of the present invention.

Fig. 11 is a block diagram of a power supply of a light string according to a third embodiment of the present invention.

Fig. 12 is a block diagram of a power supply of a light string according to a fourth embodiment of the present invention.

FIG. 13 is another block diagram of a power supply for a light string according to a fourth embodiment of the present invention.

Fig. 14 is a timing diagram illustrating the detection performed on two wires according to the fourth embodiment of the present invention.

Description of the symbols

1: power supply 100: cable

101, receiving end 102, load end

112, conducting wire 200, switching circuit

220: encoder 300: transformer

310 transformer 311 input terminal

312 output terminal 313 inverter

314 power management die 320 control circuitry

322 switching controller 324 decoder

325 remote control signal receiver 326 voltage detection unit

331, case 332, metal sheet

400 string light 500 Christmas tree

600 remote control signal emitter R resistor

R1, R2, voltage-dividing resistor REG and voltage-stabilizing regulator

CTRL, switch chips K1, K2, K3, normally open contact switch

Vcc, operating power Ve, external power

Vout drive power

Detailed Description

Referring to fig. 3 and fig. 4, a power supply 1 for a light string 400 according to a first embodiment of the present invention includes a cable 100, a switching circuit 200 and a transformer 300.

As shown in fig. 3 and 4, the cable 100 has a receiving end 101 and a loading end 102, and the cable 100 has at least two wires 112 respectively extending from the receiving end 101 to the loading end 102. Load end 102 is for connection to light string 400; load port 102 may be directly connected to light string 400 by soldering, or may be connected to light string 400 via a combination of electrical connectors. Alternatively, the two wires 112 may be part of the light string 400, and the load end 102 corresponds to a segment of the LED. The switching circuit 200 is connected across the two conductive lines 112 for selectively connecting the two conductive lines 112 to generate a voltage division.

As shown in fig. 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 310 receives external power Ve from an input terminal 311 and converts the external power Ve into driving power Vout, and the transformer 310 outputs the driving power Vout through an output terminal 312. The receiving terminal 101 of the cable 100 is electrically connected to the output terminal 312, and can output the driving power Vout to the load terminal 102.

As shown in fig. 3, the control circuit 320 is electrically connected to the transforming circuit 310 and the two conductive wires 112. The control circuit 320 detects a 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 fig. 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 plate 332 protrudes from the surface of the housing 331 and is connected to the input terminal 311. Specifically, the metal piece 332 is a pin of an ac power plug, and is inserted into an ac power outlet to receive household ac power as the external power Ve.

The driving power Vout may be a Pulse Width Modulation (PWM) signal, and is used to drive the string 400 to emit light. The control circuit 320 is used for controlling the transforming circuit 310 to change the frequency, bandwidth and PWM duty ratio of the driving power Vout, thereby adjusting the average current outputted by the transforming circuit 310 and adjusting the brightness of the light emitted by the string of lights 400.

As shown in fig. 4, in the first embodiment, the specific scheme of the switching circuit 200 is a normally open contact switch, such as a micro switch, a capacitance switch or a membrane switch, and a voltage dividing resistor R having a high resistance value is provided between the normally open contact switch and the middle wire 112 for voltage dividing control. Thus, the normally open contact switch may 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 conductive lines 112 in a segmented manner, and determines that a trigger signal is received when the voltage of the two conductive lines 112 is reduced and a voltage division is formed at two ends of the voltage dividing resistor R. The number of trigger times and the duration of trigger signals may form a combination of trigger signals in a coded pattern, so that the control circuit 320 sends a switching signal to the transformer circuit 310 to change the frequency, voltage and PWM duty ratio of the driving power Vout and adjust the brightness or flashing frequency of the light string 400. For example, a short press at a time increases the brightness of the light emitted by light string 400, a long press at a time decreases the brightness of the light emitted by light string 400, a long press plus a short press switches light string 400 to blink, a double long press switches light string 400 to blink, etc.

As shown in fig. 5 and 6, in the present invention, the position of the switching circuit 200 is moved to the cable 100 and separated from the transformer 300. Therefore, the user does not need to operate the transformer 300 for switching the output of the transformer 300, thereby avoiding the danger of high-voltage electric shock. In addition, for example, the switching circuit 200 may be a plurality of normally open contact switches, for example, 3 normally open contact switches K1, K2, and K3 are respectively disposed at different positions. Meanwhile, the voltage dividing resistors R1, R2 and R3 connected to the 3 normally open contact switches K1, K2 and K3 are not necessarily the same, but may have different resistance values. That is, when the different normally open contact switches K1, K2, and K3 are pressed, the generated voltage division is also different, and the control circuit 320 can directly switch the driving power Vout according to the different voltage division states, without pressing a single normally open contact switch for multiple times to form a code. For example, pressing K1 increases the brightness of the light string 400, pressing K2 decreases the brightness of the light string 400, pressing K3 lights or extinguishes the light string 400, and so on. In addition, different normally open contact switches K1, K2, and K3 may also be configured at different positions of the cable 100 according to the functional design; for example, when the string lights 400 are used to decorate the christmas tree 500, the normally open contact switches K1, K2, and K3 of the switching circuit 200 may be disposed on the christmas tree 500, the trunk, or hung on the leaves, or the middle section of the cable 100; at this point, the user can directly operate the switch on the Christmas tree 500.

Referring to fig. 7 and 8, a power supply 1 for a light string 400 according to a second embodiment of the present invention includes a cable 100, a switching circuit 200 and a transformer 300. In the first embodiment, the switching circuit 200 is formed by a user manually pressing a normally open contact switch to generate a trigger signal combination. In the second embodiment, the switching circuit 200 can automatically generate relatively complex combinations of trigger signals.

As shown in fig. 4, the switching circuit 200 has an encoder 220, a regulator REG, a plurality of normally open switches K1, K2, K3, and a switch chip CTRL. The regulator REG is connected to the two wires 112 to obtain the driving power Vout and convert it into the operating power Vcc, which is provided to the encoder 220 as the operating power Vcc. The switch chip CTRL is connected to the two conductive lines 112, and the switch chip CTRL is used for receiving the switch signal and generating a voltage division by connecting the switch signal to the two conductive lines 112 through the voltage division resistor R. The encoder 220 is configured with a plurality of trigger signal combinations and generates switch signals of each combination to drive the switch chip CTRL to generate voltage division by connecting the switch signals with the two wires 112 through the voltage dividing resistor R, so as to form the trigger signal combination.

As shown in fig. 7, the normally open contact switches K1, K2, and K3 are connected to the encoder 220 for being pressed to generate the selection signal, and each of the normally open contact switches K1, K2, and K3 corresponds to a trigger signal combination. Therefore, for the requirement 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, and K3, so as to drive the encoder 220 to generate the corresponding switch signal by the corresponding trigger signal combination, and drive the switch chip CTRL to generate the voltage division by connecting the voltage dividing resistor R with the two wires 112 according to the switch signal, thereby forming the trigger signal combination. The normally open contact switches K1, K2, and K3 may be micro switches, capacitance switches, or membrane switches, one end of which is connected to the encoder 220 and the other end of which is grounded, so that the corresponding contacts of the encoder 220 can be changed from high level to low level when being pressed, thereby forming a selection signal.

As shown in fig. 8, the transformer circuit 310 includes an inverter 313 and a Power management chip 314(Power IC). The inverter 313 may be a winding set or a bridge rectifier circuit. The inverter 313 is configured corresponding to the input terminal 311 for converting the household alternating current as the external power Ve into direct current. The power management die 314 is electrically connected to the inverter 313 and is disposed corresponding to the output terminal 312. The power management chip 314 is used as a power switch and a buck-boost for the dc power to output the 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 conductive wires 112, the switching controller 322 is electrically connected to the power management chip 314 and the decoder 324, and obtains the operating power Vcc from the inverter 313.

The decoder 324 is used for parsing the trigger signal combination and transmitting the 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 transforming circuit 310 to change the frequency, bandwidth or voltage of the driving power Vout, and adjust the brightness or flashing frequency of the light string 400. For example, when the normally open contact switch K1 is pressed, the brightness of the light string 400 can be increased, when the normally open contact switch K2 is pressed, the light string 400 can be switched to flicker, when the normally open contact switch K3 is pressed, the light string 400 can be switched to flicker, and the like. The number of the normally open contact switches K1, K2, and K3 is not limited to three, and may be three or more or less. In the second embodiment, the operation of connecting the two wires 112 through the voltage-dividing resistor R is performed by driving the switch chip CTRL by the encoder 220, and the time for detecting the voltage-dividing state each time can be greatly shortened, so that human eyes cannot recognize the short turn-off of the string light 400 when detecting the voltage-dividing state. In addition, the transforming circuit 310 and the switching circuit 200 of the second embodiment can also be applied to the first embodiment.

As shown in fig. 9, a method of actually detecting the divided voltage state is explained as follows. Assuming that the driving power Vout drives the string 400 at 12V, the switching controller 322 controls the power management chip 314 to output the driving power Vout at 12V after being started, so as to turn on the string 400. After every sampling time point, for example, 0.3 seconds, the power management chip 314 switches the voltage of the driving power Vout to the sampling voltage Vs, for example, to 5V, and continues for the detection time, for example, 0.015 seconds. The sampling voltage Vs is set to a voltage value that does not drive the string of lights 400 to emit light, so that the string of lights 400 is briefly extinguished. At this time, the decoder 324 performs one or more detections within the detection time, for example, after the detection time is 0.01 second, the detection is performed every 0.0005 second for 10 times, and it is determined whether a voltage division state occurs and a trigger signal combination is analyzed. The sampling voltage Vs is usually set to a low voltage value that cannot drive the string 400 to emit light, so as to avoid excessive current during detection. Although the string light 400 goes out during the detection time, the detection time is very short and the set frequency of the sampling time point is high, so that human eyes cannot observe that the string light 400 goes out temporarily.

As shown in fig. 10, similarly, one of the normally open contact switches K1, K2, and K3 may be set as a power switch. When the string light 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 a 5V sampling voltage Vs that is lower than the led start voltage and cannot light the string light 400, thereby turning off the string light 400. At this time, the transformer circuit 310 still outputs the operating power Vcc to the control circuit 320, so the decoder 324 still continues to detect the two wires 112, and when detecting that the combination corresponding to the trigger signal appears again, the switching controller 322 can be regarded as the start signal to control the power management chip 314 to raise the driving power Vout to 12V.

Referring to fig. 11, a transformer 300 according to a third embodiment of the present invention can be used to replace the transformer 300 according to the previous 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 for receiving a plurality of remote control selection signals sent by the remote control signal transmitter 600 and transmitting the remote control selection signals 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 transforming circuit 310 to change the frequency, bandwidth or voltage of the driving power Vout, and adjust the brightness or flashing frequency of the light string 400.

As shown in fig. 12 and fig. 13, a power supply 1 for a light string 400 according to a 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 be composed of a plurality of normally open contact switches K1, K2, and K3, each of the normally open contact switches K1, K2, and K3 is connected across the two wires 112 through a voltage dividing resistor R1, R2, and R3, and the resistance values of each of the voltage dividing resistors R1, R2, and R3 are different, so as 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 substantially the same as the second and third embodiments, except that the decoder 324 is replaced with a voltage detecting unit 326. The voltage detection unit 326 is connected to the two conductive wires 112, and the switching controller 322 is electrically connected to the power management chip 314 and the voltage detection unit 326, and obtains the operating power Vcc from the inverter 313.

As shown in fig. 13 and 14, the normally open contact switches K1, K2, and K3 are connected to different voltage dividing resistors R1, R2, and R3, so that different voltage divisions can be formed through the voltage dividing resistors R1, R2, and R3 when the normally open contact switches K1, K2, and K3 are pressed. The voltage detecting unit 326 can detect the divided voltage and transmit the corresponding information to the switching controller 322, so that the switching controller 322 can determine the pressed normally open contact switches K1, K2, and K3 according to the detection result and load the pressed normally open contact switches into the corresponding switching mode. The voltage detecting unit 326 may be a comparator, which compares the voltage between the two wires 112 within a certain range and outputs a corresponding detection result, so that the switching controller 322 can determine the pressed normally open contact switches K1, K2, and K3 according to the detection result. Alternatively, the voltage detecting unit 326 may be an analog-to-digital converter, which converts the voltage value into a digital signal and transmits the digital signal to the switching controller 322, so that the switching controller 322 can determine the pressed normally open contact switches K1, K2, and K3 according to the voltage value.

According to the switching mode, the switching controller 322 sends a switching signal to the transformer 310 to change the frequency, voltage and PWM duty ratio of the driving power Vout, so as to adjust the brightness or flashing frequency of the light string 400. Therefore, through the connection of the normally open contact switches K1, K2 and K3 to the voltage dividing resistors R1, R2 and R3 with different resistance values, the control circuit 320 can distinguish the different normally open contact switches K1, K2 and K3, thereby realizing the switching of multiple buttons.

The manner of actually detecting the voltage division state is shown in fig. 14. Assuming that the driving power Vout drives the string light 400 at 12V, the switching controller 322 controls the power management chip 314 to output the driving power Vout at 12V to light the string light 400 after being started. After every sampling time point, for example, 0.3 seconds, the power management chip 314 switches the voltage of the driving power Vout to the sampling voltage Vs, for example, to 5V, so that the light string 400 is extinguished temporarily and continues for the detection time, for example, 0.015 seconds. At this time, the voltage detecting unit 326 performs one or more voltage comparisons within the detection time, for example, after the detection time is 0.01 second, the voltage comparison is performed every 0.0005 seconds and compared for 10 times, it is determined whether the voltage difference between the two wires 112 is lower than the sampling voltage Vs, and the comparison result is output according to the actual voltage variation. For example, the voltage difference between the two conductive lines 112 is reduced to 2.5V by the voltage dividing resistor R1, and the voltage difference between the two conductive lines 112 is reduced to 3.5V by the voltage dividing resistor R1. When 2.5V is detected, the output comparison result corresponds to that the normally open contact switch K1 is 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 very short and the set frequency of the sampling time point is high, so that the human eye cannot observe the transient change of the string 400.

Similarly, as shown in fig. 10, one of the normally-open switches K1, K2, and K3 may be set as a power switch, and when the string 400 is turned off, the driving power Vout is reduced to a 5V sampling voltage Vs lower than the led start voltage and unable to light the string 400, so that the string 400 is turned off. At this time, the transforming circuit 310 still outputs the operating power Vcc to the control circuit 320, so the voltage detecting unit 326 and the switching controller 322 can still continuously detect the two conducting wires 112, and when the corresponding divided voltage is detected, the switching controller 322 can be regarded as a start signal to control the power management chip 314 to raise the driving power Vout to 12V to light the string light 400.

In the present invention, the position of the switching circuit 200 is moved to the cable 100, and is separated from the transformer 300. Therefore, the user does not need to operate the transformer 300 for switching the output of the transformer 300, thereby avoiding the danger of high-voltage electric shock. Meanwhile, the switching circuit 200 can be easily provided with a waterproof measure, such as being covered by a plastic film or waterproof glue, so as to reduce the risk of electric leakage of the switching circuit 200 due to moisture. In addition, because the normally open contact switches K1, K2 and K3 of the switching circuit 200 are arranged on the cable 100, the normally open contact switches K1, K2 and K3 can be arranged at any position on the cable 100 according to the design requirements of the light string 400 product, so that the diversified requirements of the product are met.

Claims (9)

1. A power supply for a light string, comprising:

the cable line is provided with a receiving end and a load end, and the cable line is provided with at least two wires which respectively extend from the receiving end to the load end;

a switching circuit connected across the two wires for selectively forming a voltage division between the two wires; and

a transformer, comprising:

the voltage transformation circuit is provided with an input end and an output end, the voltage transformation circuit receives external power from the input end and converts the external power into driving power, the driving power is output through the output end, and the receiving end of the cable is electrically connected to the output end; and

the control circuit is electrically connected with the voltage transformation circuit and the two leads; the control circuit detects the voltage division state between the two wires and sends a switching signal to the voltage transformation circuit to change the driving power according to the voltage division state.

2. The power supply of claim 1 wherein the transformer further comprises a housing and at least two metal plates, the transformer circuit and the control circuit being disposed in the housing, the metal plates protruding from the surface of the housing and being connected to the input terminal.

3. The power supply of claim 1 wherein the switching circuit is a normally open contact switch and a voltage divider resistor is disposed between the normally open contact switch and the conductive line.

4. The power supply for use in a light string as recited in claim 1,

the switching circuit comprises an encoder, a plurality of normally open contact switches, a switch wafer and a divider resistor; the normally open contact switches are connected with the encoder and used for generating corresponding selection signals when being pressed, and each normally open contact switch corresponds to a trigger signal combination; each normally open contact switch drives the encoder to generate a corresponding switch signal by each corresponding trigger signal combination, and drives the switch chip to drive the switch chip to generate partial pressure by connecting the two wires through the partial pressure resistor according to the switch signal so as to form the corresponding trigger signal combination; and

the control circuit comprises a power management chip, a switching controller and a decoder; the switching controller is electrically connected with the power management chip and the decoder, and obtains working power from the power management chip; the decoder is connected with the two wires and used for analyzing each trigger signal combination and transmitting corresponding information to the switching controller, so that the switching controller sends a switching signal to the voltage transformation circuit according to each trigger signal combination to change the driving power.

5. The power supply of claim 4 wherein the control circuit further comprises a remote control signal receiver connected to the switching controller; the remote control signal receiver is used for receiving a plurality of remote control selection signals and transmitting the remote control selection signals to the switching controller; each remote control selection signal corresponds to a switching mode, so that the switching controller sends out the switching signal to the transformation circuit to change the driving power.

6. The power supply of claim 4 wherein the transformer further comprises an inverter disposed corresponding to the input terminal for converting the external power into DC power, and the power management chip is electrically connected to the inverter for stepping up and stepping down the DC power to output the driving power.

7. The power supply of claim 4 wherein the power management chip switches the driving power voltage to a sampling voltage at every sampling time and continues for a detection time, and the decoder performs one or more detections within the detection time to determine whether a voltage division condition occurs and to resolve the trigger signal combination.

8. The power supply of claim 1 wherein the switching circuit comprises a plurality of normally open contact switches, each normally open contact switch connected across two wires through a voltage divider resistor, each voltage divider resistor having a different resistance value to form a different voltage divider when each normally open contact switch is pressed; and

the control circuit comprises 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 obtains working power from the power management chip; the voltage detection unit is connected to the two wires and used for detecting the partial voltage between the two wires and outputting a detection result to the switching controller, so that the switching controller judges the pressed normally open contact switch according to the detection result and sends a switching signal to the transformation circuit to change the driving power.

9. The power supply as claimed in claim 4, wherein the power management chip switches the voltage of the driving power to a sampling voltage at every sampling time point and continues for a detection time, the voltage detection unit performs one or more voltage detections within the detection time, determines whether the voltage difference between the two wires is lower than the sampling voltage, and outputs a detection result according to the actual voltage variation.

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