CN213342763U

CN213342763U - Two-wire system back edge light modulator

Info

Publication number: CN213342763U
Application number: CN202022523549.2U
Authority: CN
Inventors: 赖荣强
Original assignee: Vpon Electric China Co ltd
Current assignee: Vpon Electric China Co ltd
Priority date: 2020-11-05
Filing date: 2020-11-05
Publication date: 2021-06-01
Anticipated expiration: 2030-11-05

Abstract

The utility model relates to a two-wire system back edge dimmer, which comprises an AC rectification circuit, a DC voltage stabilizing circuit, a dimming control circuit and a first field effect transistor, wherein a regulated light source is electrically connected with the zero line input end of the AC rectification circuit; characterized by also comprising a load short circuit and overcurrent protection circuit, a power supply undervoltage protection circuit, a starting anti-impact protection circuit and a zero-crossing detection circuit. Has the advantages that: the LED lamp has the advantages of simple structure, good working stability and wide dimming range, the regulated light source can not be impacted when the LED lamp is started, and the LED lamp is subjected to load overcurrent protection and short-circuit protection and can be subjected to color-changing switching.

Description

Two-wire system back edge light modulator

Technical Field

The utility model relates to a two-wire system back edge light modulator, it is applicable to the dimming of LED lamp, incandescent lamp, capacitive impedance's electron electricity-saving lamp, electronic ballast fluorescent lamp and electron shot-light.

Background

At present, for the convenience of installation, there is a two-wire dimmer, such as CN201986220U, named "two-wire control-off trailing edge phase angle dimmer", which includes a full-bridge rectifier module, a variable current power supply sampling module, a low voltage dc voltage-stabilizing working power supply module, a module with adjustable trailing edge for turning off phase angle, a conducting phase angle setting module, a time-base circuit and a field effect transistor Q3, one input end of the full-bridge rectifier module is connected to a live wire, the other input end of the full-bridge rectifier module is connected to a load, which is connected to a zero wire, the output end of the full-bridge rectifier module is connected in parallel to the variable current power supply sampling module and the field effect transistor Q3, the input end of the variable current power supply sampling module is connected to one input end of the variable current power supply module, the output end of the variable current power supply sampling module is connected to, The adjustable module of the back edge of the turn-off phase angle and the setting module of the conduction phase angle are both connected in parallel between the output end of the current-converting power supply module and the negative output end of the full-bridge rectification module, the output end of the adjustable module of the back edge of the turn-off phase angle and the output end of the setting module of the conduction phase angle are respectively connected with the input end of the time base circuit, and the output end of the time base circuit is connected with the grid electrode of the field effect transistor Q3. It has the problems that: the structure is more complicated, and job stabilization nature is not good, and the scope of adjusting luminance is not wide, and strikes when starting, no load overcurrent protection and short-circuit protection, can't change the colour to the polychrome temperature LED lamp and switch.

Disclosure of Invention

The utility model aims at overcoming prior art not enough and providing a two-wire system back edge light modulator, its simple structure, job stabilization nature is good, and the scope of adjusting luminance is wide, is regulated and control the light source LMP and can not receive the impact during the start-up.

In order to achieve the purpose, the utility model discloses a two-wire system back porch dimmer, including alternating current rectifier circuit, direct current voltage stabilizing circuit, dimming control circuit and first field effect transistor, the zero line input end at alternating current rectifier circuit is connected to the light source LMP electricity of being regulated and control; the circuit is characterized by also comprising a load short circuit and overcurrent protection circuit, a power supply undervoltage protection circuit, a starting impact protection circuit and a zero-crossing detection circuit;

the positive output end of the alternating current rectification circuit inputs rectified signals to the input end of the direct current voltage stabilizing circuit, the input end of the zero-crossing detection circuit and the drain electrode of the first field effect transistor respectively, the negative output end of the alternating current rectification circuit is grounded, and the output end of the direct current voltage stabilizing circuit outputs direct current working voltage VCC;

the input end of the load short-circuit and overcurrent protection circuit is electrically connected with the source electrode of the first field effect transistor and used for sensing the current of the source electrode of the first field effect transistor, the load short-circuit and overcurrent protection circuit converts the sensed current of the source electrode of the first field effect transistor into a voltage signal and then inputs the voltage signal to the low-level reset input end of the dimming control circuit from one output end so as to control the reset of the dimming control circuit, and the other output end of the load short-circuit and overcurrent protection circuit is electrically connected with the grounding end of the alternating current rectification circuit;

the input end of the power supply undervoltage protection circuit receives a voltage signal of the output end of the direct current voltage stabilizing circuit and judges whether the voltage is undervoltage or not, and the output end of the power supply undervoltage protection circuit is electrically connected with the grid electrode of the first field effect tube to control the first field effect tube to be in saturation conduction or cut off;

the input end of the starting anti-shock protection circuit receives and buffers a voltage signal of the output end of the direct current voltage stabilizing circuit, and the output end of the starting anti-shock protection circuit is electrically connected with the high-level trigger input end of the dimming control circuit and used for delaying the work of the dimming control circuit so as to control the saturation conduction or the turn-off of the first field effect transistor and prevent the regulated light source LMP from being impacted;

the output end of the zero-crossing detection circuit is electrically connected with the low level trigger end of the dimming control circuit, so that the dimming control circuit can trigger to work under the set level to control the saturation conduction or the turn-off of the first field effect transistor;

the output end of the dimming control circuit is electrically connected with the grid electrode of the first field effect transistor and used for controlling the saturation conduction or the turn-off of the first field effect transistor, and the power supply end of the dimming control circuit is connected with a direct-current working voltage VCC.

In the technical scheme, the alternating current rectifier circuit further comprises a selection switch, and the selection switch is electrically connected to the live wire input end of the alternating current rectifier circuit.

In the technical scheme, the direct current voltage stabilizing circuit comprises a second field effect transistor, a first diode, a second voltage stabilizing diode, a fifth resistor, a sixth resistor, a second capacitor and an electrolytic capacitor; one end of the fifth resistor is electrically connected with the forward output end of the alternating current rectifying circuit, the other end of the fifth resistor is electrically connected with the anode of the first diode, the cathode of the first diode is electrically connected with one end of the sixth resistor and the drain electrode of the second field effect transistor respectively, the other end of the sixth resistor is electrically connected with the cathode of the second voltage stabilizing diode and the grid electrode of the second field effect transistor respectively, the second capacitor is connected with the electrolytic capacitor in parallel, the positive end of the electrolytic capacitor is electrically connected with the source electrode of the second field effect transistor, the negative end of the electrolytic capacitor is electrically connected with the anode of the second voltage stabilizing diode and grounded, and the source electrode of the second field effect transistor is the output end of the working voltage VCC of the direct current voltage stabilizing circuit.

In the technical scheme, the dimming control circuit comprises a dimming resistor group, a time-base integrated block, an eleventh resistor, a fifteenth resistor, and sixth to eighth capacitors; the model of the time base integrated block is NE555, and there are eight pins in total, one end of the dimming resistor group and 8 pins of the time base integrated block are all connected with a working voltage VCC, the other end of the dimming resistor group is respectively and electrically connected with 6 pins and 7 pins of the time base integrated block and one end of an eighth capacitor through an eleventh resistor, one end of a sixth capacitor and one end of a fifteenth resistor are electrically connected with a grid electrode of the first field effect transistor through a second resistor, the other end of the fifteenth resistor is electrically connected with 3 pins of the time base integrated block, one end of a seventh capacitor is electrically connected with 5 pins of the time base integrated block, the other end of the sixth capacitor, the other end of the seventh capacitor, the other end of the eighth capacitor and 5 pins of the time base integrated block are all grounded.

In the technical scheme, the load short-circuit and overcurrent protection circuit comprises a first resistor, a sixteenth resistor, a seventeenth resistor, a ninth capacitor and a seventh triode; one end of the first resistor is electrically connected with a source electrode of the first field effect transistor and one end of the seventeenth resistor respectively, the other end of the first resistor is grounded, the other end of the seventeenth resistor is electrically connected with a base electrode of the seventh triode, a collector electrode of the seventh triode is electrically connected with one end of the sixteenth resistor, one end of the ninth capacitor and 4 pins of the base integration block respectively, an emitting electrode of the seventh triode and the other end of the ninth capacitor are grounded, and the other end of the sixteenth resistor is connected with a working voltage VCC.

In the technical scheme, the power supply undervoltage protection circuit comprises a fifth triode, a sixth triode, a third voltage stabilizing diode and twelfth to fourteenth resistors; the base electrode of the fifth triode is electrically connected with the anode of the third voltage stabilizing diode and one end of the second resistor through a thirteenth resistor, the collector electrode of the fifth triode is electrically connected with the base electrode of the sixth triode and one end of the fourteenth resistor, the emitter electrode of the fifth triode, the emitter electrode of the sixth triode and the other end of the twelfth resistor are all grounded, the cathode of the third voltage stabilizing diode and the other end of the fourteenth resistor are all connected with a working voltage VCC, and the collector electrode of the sixth triode is electrically connected with the grid electrode of the first field effect transistor through the second resistor.

In the technical scheme, the starting anti-shock protection circuit comprises a second diode, a third triode, a fourth triode, a third capacitor, a fifth capacitor, a seventh resistor, a fifth resistor and a tenth resistor; the positive electrode of the second diode is electrically connected with the grid electrode of the second field effect transistor, the negative electrode of the second diode is respectively electrically connected with the negative electrode of the third diode, one end of a seventh resistor and one end of a third capacitor, the positive electrode of the third diode is electrically connected with the base electrode of the third triode, the emitter electrode of the third triode, the collector electrode of the fourth triode and one end of a fifth capacitor are all connected with a working voltage VCC, the collector electrode of the third triode is electrically connected with one end of an eighth resistor, the base electrode of the fourth triode is respectively electrically connected with the other end of the fifth capacitor, the negative electrode of the fourth diode and one end of a ninth resistor, the emitter electrode of the fourth triode is electrically connected with one end of a tenth resistor, the other end of the tenth resistor is electrically connected with the 6-pin of the time-base integrated block through an eleventh resistor, the other end of the seventh resistor, the other end of the eighth resistor and, The anode of the fourth diode and the other end of the ninth resistor are both grounded.

In the technical scheme, the zero-crossing detection circuit comprises a third resistor, a fourth resistor, a first voltage stabilizing diode, a fourth capacitor and a fifth diode; one end of the third resistor is electrically connected with the forward output end of the alternating current rectification circuit, the other end of the third resistor is electrically connected with one end of the fourth resistor, the negative electrode of the first voltage stabilizing diode and one end of the fourth capacitor respectively, the other end of the fourth resistor and the positive electrode of the first voltage stabilizing diode are grounded, the other end of the fourth capacitor is electrically connected with the positive electrode of the fifth diode and the 2-pin of the time-based integrated block respectively, and the negative electrode of the fifth diode is connected with the working voltage VCC.

In the technical scheme, the dimming resistor group comprises a minimum brightness dimming resistor, a maximum brightness dimming resistor and a main brightness dimming resistor; one end of the minimum brightness dimming resistor, one end of the maximum brightness dimming resistor, one end of the main brightness dimming resistor, the adjustable end of the minimum brightness dimming resistor and the adjustable end of the maximum brightness dimming resistor are all connected with a working voltage VCC, the other end of the minimum brightness dimming resistor is electrically connected with the adjustable end of the main brightness dimming resistor, and the other end of the maximum brightness dimming resistor and the other end of the main brightness dimming resistor are electrically connected and are electrically connected with 6 pins of the time-base integrated block through an eleventh resistor.

Compared with the prior art, the utility model the advantage do: the LED lamp has the advantages of simple structure, good working stability and wide dimming range, the regulated light source LMP can not be impacted when the LED lamp is started, and the LED lamp is subjected to load overcurrent protection and short-circuit protection and can be subjected to color-changing switching.

Drawings

Fig. 1 is a circuit block diagram of the present invention;

fig. 2 is a schematic circuit diagram of the present invention.

Detailed Description

The following describes the present invention with reference to the accompanying drawings. It should be noted that the description of the embodiments is provided to help understanding of the present invention, but the present invention is not limited thereto. Furthermore, the technical features mentioned in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

In the description of the present invention, the terms "first" to "seventeenth" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

As shown in fig. 1, the two-wire system trailing edge dimmer comprises an ac rectification circuit 1, a dc voltage stabilizing circuit 2, a load short circuit and overcurrent protection circuit 3, a power supply undervoltage protection circuit 4, a start-up anti-shock protection circuit 5, a zero-cross detection circuit 6, a dimming control circuit 7, a selector switch K and a first field effect transistor Q1, wherein a regulated light source LMP is electrically connected to a zero line input end of the ac rectification circuit 1, and the selector switch K is electrically connected to a live line input end of the ac rectification circuit 1.

The positive output end of the alternating current rectification circuit 1 inputs rectified signals to the input end of the direct current voltage stabilizing circuit 2, the input end of the zero-crossing detection circuit 6 and the drain electrode of the first field effect transistor Q1 respectively, the negative output end of the alternating current rectification circuit 1 is grounded, and the output end of the direct current voltage stabilizing circuit 2 outputs direct current working voltage VCC.

The input end of the load short-circuit and overcurrent protection circuit 3 is electrically connected with the source electrode of the first field-effect tube Q1 and is used for sensing the current of the source electrode of the first field-effect tube Q1, the load short-circuit and overcurrent protection circuit 3 converts the sensed current of the source electrode of the first field-effect tube Q1 into a voltage signal and then inputs the voltage signal to the low-level reset input end of the dimming control circuit 7 from one output end so as to control the reset of the dimming control circuit 7, and the other output end of the load short-circuit and overcurrent protection circuit 3 is electrically connected with the grounding end of the alternating current rectification circuit; when the light source works, if the current of the source electrode of the first field effect transistor Q1 is in the amplification region, the load short circuit and overcurrent protection circuit 3 outputs a low level to the reset input end of the dimming control circuit 7, the dimming control circuit 7 is reset, the grid electrode of the first field effect transistor Q1 is at the low level, and the first field effect transistor Q1 is cut off, so that the damage caused by heating of the first field effect transistor Q1 is avoided, and the regulated light source LMP is not bright; if the current of the source electrode of the first field effect transistor Q1 is not in the amplification region, the load short circuit and overcurrent protection circuit 3 outputs high level to the dimming control circuit 7, the dimming control circuit 7 is not reset, the saturation and cut-off of the first field effect transistor Q1 are not influenced, and the regulated light source LMP is on.

The input end of the power supply undervoltage protection circuit 4 receives a direct-current working voltage signal at the output end of the direct-current voltage stabilizing circuit 2 and judges whether undervoltage exists or not, and the output end of the power supply undervoltage protection circuit 4 is electrically connected with the grid electrode of the first field-effect tube Q1 to control the first field-effect tube Q1 to be in saturation conduction or cut-off; when the power supply is in work, if the power supply undervoltage protection circuit 4 induces that the direct-current working voltage at the output end of the direct-current voltage stabilizing circuit 2 is lower than the set direct-current working voltage, the power supply undervoltage protection circuit 4 outputs a low level to the grid of the first field-effect tube Q1, and the first field-effect tube Q1 is cut off, so that the damage caused by heating of the first field-effect tube Q1 is avoided, and the regulated light source LMP is not bright; if the undervoltage protection circuit 4 senses that the direct-current working voltage at the output end of the direct-current voltage stabilizing circuit 2 is within the set direct-current working voltage range, the undervoltage protection circuit 4 is opened, the work of the first field-effect tube Q1 is not affected, and the regulated light source LMP is on.

The input end of the start anti-shock protection circuit 5 receives and buffers a voltage signal at the output end of the direct current voltage stabilizing circuit 2, and the output end of the start anti-shock protection circuit 5 is electrically connected with the high-level trigger input end of the dimming control circuit 7 and used for delaying the work of the dimming control circuit 7 so as to control the saturation conduction or the turn-off of the first field-effect tube Q1 and prevent the regulated light source LMP from being impacted; when the direct current voltage stabilizing circuit works, the output end of the direct current voltage stabilizing circuit 2 firstly charges the starting anti-shock protection circuit 5, when the voltage of the high-level trigger input end of the dimming control circuit 7 is reached, the dimming control circuit 7 works and outputs high level or low level to the first field-effect tube Q1, the first field-effect tube Q1 is alternately saturated and switched on and off, and the regulated light source LMP is bright; when power is off, the start-up anti-shock protection circuit 5 can discharge quickly.

The output end of the zero-crossing detection circuit 6 is electrically connected with the low level trigger end of the dimming control circuit 7, so that the dimming control circuit 7 can trigger to work under a set level to control the saturation on or off of the first field effect transistor Q1; during operation, when the voltage detected by the zero-cross detection circuit 6 is low, the dimming control circuit 7 can operate at a relatively low level, so that the operating stability of the first field effect transistor Q1 is improved.

The output end of the dimming control circuit 7 is electrically connected with the grid of the first field effect transistor Q1 and is used for controlling the saturation on/off of the first field effect transistor Q1, and the power supply end of the dimming control circuit 7 is connected with a direct-current working voltage VCC. When the dimming control circuit 7 works, the dimming control circuit can output a pulse signal with a variable frequency, so that the saturated conduction and cut-off frequency of the first field effect transistor Q1 is adjusted, and the purpose of adjusting the brightness of the regulated light source LMP is achieved.

In the present embodiment, as shown in fig. 1 and fig. 2, the ac rectification circuit 1 includes a bridge rectifier diode DB, a first capacitor C1, a first adjustable resistor DR1, and a fuse F; the positive output end of the bridge rectifier diode DB is the positive output end of the alternating current rectification circuit 1, the negative output end of the bridge rectifier diode DB is the negative output end of the alternating current rectification circuit 1, one input end of the bridge rectifier diode DB is electrically connected with one end of a first capacitor C1, one end of a first adjustable resistor DR1 and one end of a regulated light source LMP respectively, the other end of the regulated light source LMP is connected with a zero line of commercial alternating current, the other input end of the bridge rectifier diode DB is electrically connected with the other end of a first capacitor C1, the other end of a first adjustable resistor DR1 and one end of a selector switch K respectively, the other end of the selector switch K is electrically connected with one end of a fuse F, and the other end of the fuse F is electrically connected with a live line of the alternating current. When the alternating current rectifier works, commercial alternating current is rectified by the bridge rectifier diode DB and then outputs sine wave voltage of positive half cycle.

In this embodiment, as shown in fig. 1 and fig. 2, the dc voltage regulator circuit 2 includes a second fet Q2, a first diode D1, a second zener diode ZD2, a fifth resistor R5, a sixth resistor R6, a second capacitor C2, and an electrolytic capacitor E; one end of the fifth resistor R5 is electrically connected with the forward output end of the ac rectification circuit 1, the other end of the fifth resistor R5 is electrically connected with the anode of the first diode D1, the cathode of the first diode D1 is electrically connected with one end of the sixth resistor R6 and the drain of the second field-effect transistor Q2, the other end of the sixth resistor R6 is electrically connected with the cathode of the second zener diode ZD2 and the gate of the second field-effect transistor Q2, the second capacitor C2 is connected in parallel with the electrolytic capacitor E, the positive end of the electrolytic capacitor E is electrically connected with the source of the second field-effect transistor Q2, the negative end of the electrolytic capacitor E is electrically connected with the anode of the second zener diode ZD2 and grounded, and the source of the second field-effect transistor Q2 is the output end of the working voltage VCC of the dc voltage stabilizing circuit 2. During operation, the positive half cycle sine wave voltage output by the bridge rectifier diode DB passes through the fifth resistor R5, the first diode D1, the sixth resistor R6 and the second zener diode ZD2 in sequence, and then the dc operating voltage VCC is output at the gate of the second field effect transistor Q2.

In the present embodiment, as shown in fig. 1 and fig. 2, the dimming control circuit 7 includes a dimming resistor set, a time-base integrated block U, an eleventh resistor R11, a fifteenth resistor R15, and sixth to eighth capacitors C6 to C8; the model of the time-base integrated block U is NE555, eight pins are provided, pin 2 of the time-base integrated block U is a low-level trigger input end of the dimming control circuit 7, pin 3 of the time-base integrated block U is an output end of the dimming control circuit 7, pin 4 of the time-base integrated block U is a low-level reset input end of the dimming control circuit 7, and pin 6 of the time-base integrated block U is a high-level trigger input end of the dimming control circuit 7; one end of the dimming resistor group and the 8 pin of the time-base integrated block U are all connected with a working voltage VCC, the other end of the dimming resistor group is respectively and electrically connected with the 6 pin and the 7 pin of the time-base integrated block U and one end of an eighth capacitor C8 through an eleventh resistor R11, one end of a sixth capacitor C6 and one end of a fifteenth resistor R15 are electrically connected with the gate of the first field-effect tube Q1 through a second resistor R2, the other end of the fifteenth resistor R15 is electrically connected with the 3 pin of the time-base integrated block U, one end of a seventh capacitor C7 is electrically connected with the 5 pin of the time-base integrated block U, the other end of the sixth capacitor C6, the other end of the seventh capacitor C7, the other end of the eighth capacitor C8 and the 1 pin of the time-base integrated block U are all grounded. When the light source LMP dimming circuit works, the size of the dimming resistor group is adjusted, so that the charging and discharging time of the eighth capacitor C8 is adjusted, the output pulse frequency of the time base integrated block U is changed, the saturated conducting and cut-off frequency of the first field-effect tube Q1 is adjusted, and the purpose of adjusting and controlling the brightness of the light source LMP is achieved.

In this embodiment, as shown in fig. 1 and fig. 2, the load short-circuit and overcurrent protection circuit 3 includes a first resistor R1, a sixteenth resistor R16, a seventeenth resistor R17, a ninth capacitor C9, and a seventh transistor Q7; one end of the first resistor R1 is electrically connected with the source of the first field-effect transistor Q1 and one end of the seventeenth resistor R17, the other end of the first resistor R1 is grounded, the other end of the seventeenth resistor R17 is electrically connected with the base of the seventh triode Q7, the collector of the seventh triode Q7 is electrically connected with one end of the sixteenth resistor R16, one end of the ninth capacitor C9 and the 4 pins of the time-based integrated block U, the emitter of the seventh triode Q7 and the other end of the ninth capacitor C9 are grounded, and the other end of the sixteenth resistor R16 is connected with the dc working voltage VCC. When the high-voltage power supply works, when the current flowing through the first resistor R1 becomes large, the seventh triode Q7 is in saturated conduction, the pin 4 of the time base integrated block U is at a low level, the time base integrated block U resets, the first field-effect tube Q1 is cut off, and short circuit and overcurrent protection are achieved.

In this embodiment, as shown in fig. 1 and fig. 2, the under-voltage power protection circuit 4 includes a fifth transistor Q5, a sixth transistor Q6, a third zener diode ZD3, and twelfth to fourteenth resistors R12 to R14; the base electrode of the fifth triode Q5 is electrically connected with the anode of the third voltage-stabilizing diode ZD3 and one end of the second resistor R12 through the thirteenth resistor R13, the collector electrode of the fifth triode Q5 is electrically connected with the base electrode of the sixth triode Q6 and one end of the fourteenth resistor R14, the emitter electrode of the fifth triode Q5, the emitter electrode of the sixth triode Q6 and the other end of the twelfth resistor R12 are all grounded, the cathode of the third voltage-stabilizing diode ZD3 and the other end of the fourteenth resistor R14 are both connected with the working voltage VCC, and the collector electrode of the sixth triode Q6 is electrically connected with the gate electrode of the first field-effect transistor Q1 through the second resistor R2. When the power supply is in work, if an undervoltage condition occurs, the fifth triode Q5 is cut off, and the sixth triode Q6 is in saturation conduction, so that the first field effect transistor Q1 is cut off, and the purpose of power supply undervoltage protection is achieved.

In this embodiment, as shown in fig. 1 and fig. 2, the start-up anti-shock protection circuit 5 includes a second diode D2 to a fourth diode D4, a third transistor Q3, a fourth transistor Q4, a third capacitor C3, a fifth capacitor C5, and a seventh resistor R7 to a tenth resistor R10; the anode of the second diode D2 is electrically connected to the gate of the second fet Q2, the cathode of the second diode D2 is electrically connected to the cathode of the third diode D3, one end of the seventh resistor R7 and one end of the third capacitor C3, respectively, the anode of the third diode D3 is electrically connected to the base of the third transistor Q3, the emitter of the third transistor Q3, the collector of the fourth transistor Q4 and one end of the fifth capacitor C5 are all connected to the dc working voltage VCC, the collector of the third transistor Q3 is electrically connected to one end of the eighth resistor R8, the base of the fourth transistor Q4 is electrically connected to the other end of the fifth capacitor C5, the cathode of the fourth diode D4 and one end of the ninth resistor R9, the emitter of the fourth transistor Q4 is electrically connected to one end of the tenth resistor R10, the other end of the tenth resistor R10 is electrically connected to the pin 5396 of the time-base integrated block U through the eleventh resistor R11, the other end of the seventh resistor R7, the other end of the eighth resistor R8, the other end of the third capacitor C3, the anode of the fourth diode D4, and the other end of the ninth resistor R9 are all grounded. When the voltage regulator works, when the voltage regulator is started, the direct-current working voltage VCC charges the fifth capacitor C5, and when the saturated conduction energy of the fourth triode Q4 is reached, the level of the 6 pin of the time-base integrated block U meets the requirement to start working, so that the impact on the regulated light source LMP is reduced, and the purpose of starting anti-impact protection is achieved; when the power is off, the third triode Q3 is saturated and can conduct energy, the fifth capacitor C5 can discharge rapidly, preparation is made for next work, the regulated light source LMP is protected, and the purpose of starting anti-impact protection is achieved.

In the present embodiment, as shown in fig. 1 and fig. 2, the zero-cross detection circuit 6 includes a third resistor R3, a fourth resistor R4, a first zener diode ZD1, a fourth capacitor C4, and a fifth diode D5; one end of the third resistor R3 is electrically connected with the forward output end of the alternating current rectification circuit 1, the other end of the third resistor R3 is electrically connected with one end of the fourth resistor R4, the cathode of the first zener diode ZD1 and one end of the fourth capacitor C4, the other end of the fourth resistor R4 and the anode of the first zener diode ZD1 are both grounded, the other end of the fourth capacitor C4 is electrically connected with the anode of the fifth diode D5 and the 2-pin of the time-based integrated block U, and the cathode of the fifth diode D5 is connected with the direct current working voltage VCC. During operation, when the voltage at the voltage division point of the third resistor R3 and the fourth resistor R4 is low, the pin 2 of the time-base integrated block U is a low-level trigger end, so that the time-base integrated block U can also operate more stably.

In the present embodiment, as shown in fig. 1 and fig. 2, the dimming resistor set includes a minimum brightness dimming resistor DR2, a maximum brightness dimming resistor DR3, and a main brightness dimming resistor DR 4; one end of the minimum brightness dimming resistor DR2, one end of the maximum brightness dimming resistor DR3, one end of the main brightness dimming resistor DR4, the adjustable end of the minimum brightness dimming resistor DR2 and the adjustable end of the maximum brightness dimming resistor DR3 are all connected with the working voltage VCC, the other end of the minimum brightness dimming resistor DR2 is electrically connected with the adjustable end of the main brightness dimming resistor DR4, and the other end of the maximum brightness dimming resistor DR3 and the other end of the main brightness dimming resistor DR4 are electrically connected and electrically connected with the pin 6 of the time base integration block U through an eleventh resistor R11. During operation, the minimum brightness of the regulated light source LMP can be regulated through the minimum brightness dimming resistor DR2, the maximum brightness of the regulated light source LMP can be regulated through the maximum brightness dimming resistor DR3, the charging and discharging time of the eighth capacitor C8 is changed by regulating the main brightness dimming resistor DR4 by a user, so that the frequency of the output pulse of the 6 pins of the time base integrated block U is changed, the frequency of the saturated conduction and cut-off of the first field effect transistor Q1 is controlled, and the purpose of dimming is achieved.

The embodiments of the present invention are described in detail with reference to the drawings, but the present invention is not limited to the described embodiments. It will be apparent to those skilled in the art that various changes, modifications, substitutions and alterations can be made in the embodiments without departing from the principles and spirit of the invention.

Claims

1. A two-wire system back edge dimmer comprises an alternating current rectification circuit (1), a direct current voltage stabilizing circuit (2), a dimming control circuit (7) and a first field effect transistor (Q1), wherein a regulated light source LMP is electrically connected to the zero line input end of the alternating current rectification circuit (1); the circuit is characterized by also comprising a load short circuit and overcurrent protection circuit (3), a power supply undervoltage protection circuit (4), a starting impact protection circuit (5) and a zero-crossing detection circuit (6);

the positive output end of the alternating current rectification circuit (1) respectively inputs rectified signals to the input end of the direct current voltage stabilizing circuit (2), the input end of the zero-crossing detection circuit (6) and the drain electrode of the first field effect transistor (Q1), the negative output end of the alternating current rectification circuit (1) is grounded, and the output end of the direct current voltage stabilizing circuit (2) outputs direct current working voltage VCC;

the input end of the load short-circuit and overcurrent protection circuit (3) is electrically connected with the source electrode of the first field effect transistor (Q1) and is used for sensing the current of the source electrode of the first field effect transistor (Q1), the load short-circuit and overcurrent protection circuit (3) converts the sensed current of the source electrode of the first field effect transistor (Q1) into a voltage signal and then inputs the voltage signal to the low-level reset input end of the dimming control circuit (7) from one output end so as to control the reset of the dimming control circuit (7), and the other output end of the load short-circuit and overcurrent protection circuit (3) is electrically connected with the grounding end of the alternating current rectification circuit (1);

the input end of the power supply undervoltage protection circuit (4) receives a voltage signal of the output end of the direct current voltage stabilizing circuit (2) and judges whether undervoltage exists or not, and the output end of the power supply undervoltage protection circuit (4) is electrically connected with the grid electrode of the first field-effect tube (Q1) to control the first field-effect tube (Q1) to be in saturation conduction or cutoff;

the input end of the starting anti-shock protection circuit (5) receives a voltage signal of the output end of the direct-current voltage stabilizing circuit (2) and buffers the voltage signal, and the output end of the starting anti-shock protection circuit (5) is electrically connected with the high-level trigger input end of the dimming control circuit (7) and used for delaying the work of the dimming control circuit (7) so as to control the saturation conduction or the turn-off of the first field-effect tube (Q1) and prevent the regulated light source LMP from being impacted;

the output end of the zero-crossing detection circuit (6) is electrically connected with the low level trigger end of the dimming control circuit (7), so that the dimming control circuit (7) can trigger to work under a set level to control the saturation on or off of the first field effect transistor (Q1);

the output end of the dimming control circuit (7) is electrically connected with the grid of the first field-effect tube (Q1) and is used for controlling the saturation on or off of the first field-effect tube (Q1), and the power supply end of the dimming control circuit (7) is connected with a direct-current working voltage VCC.

2. The two-wire trailing edge dimmer according to claim 1, further comprising a selector switch (K) electrically connected to the hot input of the ac rectifying circuit (1).

3. The two-wire trailing edge dimmer according to claim 1, wherein the dc voltage stabilizing circuit (2) comprises a second field effect transistor (Q2), a first diode (D1), a second zener diode (ZD 2), a fifth resistor (R5), a sixth resistor (R6), a second capacitor (C2), and an electrolytic capacitor (E); one end of the fifth resistor (R5) is electrically connected with the positive output end of the alternating current rectifying circuit (1), the other end of the fifth resistor (R5) is electrically connected with the positive electrode of the first diode (D1), the cathode of the first diode (D1) is respectively and electrically connected with one end of a sixth resistor (R6) and the drain electrode of the second field effect transistor (Q2), the other end of the sixth resistor (R6) is respectively and electrically connected with the cathode of the second voltage-stabilizing diode (ZD 2) and the grid of the second field effect transistor (Q2), the second capacitor (C2) is connected with the electrolytic capacitor (E) in parallel, the positive end of the electrolytic capacitor (E) is electrically connected with the source electrode of the second field-effect tube (Q2), the negative end of the electrolytic capacitor (E) is electrically connected with the positive electrode of the second voltage-stabilizing diode (ZD 2) and grounded, and the source electrode of the second field-effect tube (Q2) is the output end of the working voltage VCC of the direct current voltage stabilizing circuit (2).

4. The two-wire trailing edge dimmer according to claim 3, wherein the dimming control circuit (7) comprises a dimming resistor bank, a time base integrated block (U), an eleventh resistor (R11), a fifteenth resistor (R15), and sixth through eighth capacitors (C6-C8); the model of the time base integrated block (U) is NE555, eight pins are provided, one end of the dimming resistor group and the 8 pins of the time base integrated block (U) are both connected with a working voltage VCC, the other end of the dimming resistor group is respectively and electrically connected with the 6 pins and the 7 pins of the time base integrated block (U) and one end of an eighth capacitor (C8) through an eleventh resistor (R11), one end of the sixth capacitor (C6) and one end of the fifteenth resistor (R15) are electrically connected with the grid electrode of the first field effect transistor (Q1) through the second resistor (R2), the other end of the fifteenth resistor (R15) is electrically connected with the 3 pins of the time base integrated block (U), one end of the seventh capacitor (C7) is electrically connected with the 5 pin of the time base integrated block (U), the other end of the sixth capacitor (C6), the other end of the seventh capacitor (C7), the other end of the eighth capacitor (C8) and the 1 pin of the time base integrated block (U) are all grounded.

5. The two-wire trailing edge dimmer according to claim 4, wherein the load short and overcurrent protection circuit (3) comprises a first resistor (R1), a sixteenth resistor (R16), a seventeenth resistor (R17), a ninth capacitor (C9) and a seventh transistor (Q7); one end of the first resistor (R1) is respectively electrically connected with the source of the first field-effect transistor (Q1) and one end of the seventeenth resistor (R17), the other end of the first resistor (R1) is grounded, the other end of the seventeenth resistor (R17) is electrically connected with the base of the seventh triode (Q7), the collector of the seventh triode (Q7) is respectively electrically connected with one end of the sixteenth resistor (R16), one end of the ninth capacitor (C9) and the 4 pins of the base integrated block (U), the emitter of the seventh triode (Q7) and the other end of the ninth capacitor (C9) are grounded, and the other end of the sixteenth resistor (R16) is connected with the working voltage VCC.

6. The two-wire trailing edge dimmer according to claim 1, wherein the brown-out protection circuit (4) comprises a fifth transistor (Q5), a sixth transistor (Q6), a third zener diode (ZD 3), and twelfth to fourteenth resistors (R12) to (R14); the base electrode of the fifth triode (Q5) is electrically connected with the positive electrode of the third voltage-stabilizing diode (ZD 3) and one end of the second resistor (R12) through a thirteenth resistor (R13), the collector electrode of the fifth triode (Q5) is electrically connected with the base electrode of the sixth triode (Q6) and one end of the fourteenth resistor (R14), the emitter electrode of the fifth triode (Q5), the emitter electrode of the sixth triode (Q6) and the other end of the twelfth resistor (R12) are all grounded, the negative electrode of the third voltage-stabilizing diode (ZD 3) and the other end of the fourteenth resistor (R14) are both connected with the working voltage VCC, and the collector electrode of the sixth triode (Q6) is electrically connected with the gate electrode of the first field-effect transistor (Q1) through the second resistor (R2).

7. The two-wire trailing edge dimmer according to claim 4, wherein the start-up shock protection circuit (5) comprises a second diode (D2) to a fourth diode (D4), a third transistor (Q3), a fourth transistor (Q4), a third capacitor (C3), a fifth capacitor (C5), and a seventh resistor (R7) to a tenth resistor (R10); the anode of the second diode (D2) is electrically connected with the gate of the second field effect transistor (Q2), the cathode of the second diode (D2) is electrically connected with the cathode of the third diode (D3), one end of the seventh resistor (R7) and one end of the third capacitor (C3) respectively, the anode of the third diode (D3) is electrically connected with the base of the third triode (Q3), the emitter of the third triode (Q3), the collector of the fourth triode (Q4) and one end of the fifth capacitor (C5) are all connected with the working voltage VCC, the collector of the third triode (Q3) is electrically connected with one end of the eighth resistor (R8), the base of the fourth triode (Q4) is electrically connected with the other end of the fifth capacitor (C2), the cathode of the fourth diode (D4) and one end of the ninth resistor (R9) respectively, the emitter of the fourth triode (Q4) is electrically connected with one end of the tenth resistor (R10), the other end of the tenth resistor (R10) is electrically connected with the 6 th pin of the time base integrated block (U) through an eleventh resistor (R11), and the other end of the seventh resistor (R7), the other end of the eighth resistor (R8), the other end of the third capacitor (C3), the anode of the fourth diode (D4) and the other end of the ninth resistor (R9) are all grounded.

8. The two-wire trailing edge dimmer according to claim 4, wherein the zero-cross detection circuit (6) comprises a third resistor (R3), a fourth resistor (R4), a first zener diode (ZD 1), a fourth capacitor (C4), and a fifth diode (D5); one end of the third resistor (R3) is electrically connected with the forward output end of the alternating current rectifying circuit (1), the other end of the third resistor (R3) is electrically connected with one end of the fourth resistor (R4), the negative electrode of the first voltage stabilizing diode (ZD 1) and one end of the fourth capacitor (C4) respectively, the other end of the fourth resistor (R4) and the positive electrode of the first voltage stabilizing diode (ZD 1) are grounded, the other end of the fourth capacitor (C4) is electrically connected with the positive electrode of the fifth diode (D5) and the 2 pin of the time-base integrated block (U) respectively, and the negative electrode of the fifth diode (D5) is connected with the working voltage VCC.

9. The two-wire trailing edge dimmer according to claim 4, wherein the dimming resistor set comprises a minimum brightness dimming resistor (DR 2), a maximum brightness dimming resistor (DR 3), and a main brightness dimming resistor (DR 4); one end of the minimum brightness dimming resistor (DR 2), one end of the maximum brightness dimming resistor (DR 3), one end of the main brightness dimming resistor (DR 4), the adjustable end of the minimum brightness dimming resistor (DR 2) and the adjustable end of the maximum brightness dimming resistor (DR 3) are all connected with a working voltage VCC, the other end of the minimum brightness dimming resistor (DR 2) is electrically connected with the adjustable end of the main brightness dimming resistor (DR 4), and the other end of the maximum brightness dimming resistor (DR 3) and the other end of the main brightness dimming resistor (DR 4) are electrically connected and electrically connected with the 6 pins of the time base integrated block (U) through an eleventh resistor (R11).