A dimming lamp state detection circuit

Abstract

The present invention belongs to the technical field of detection of dimmable lights, and particularly relates to a state detection circuit for a dimmable light, comprising: a first transistor controllably connected between a voltage output terminal and a ground terminal under the control of the voltage of the negative electrode of an LED lamp; a second transistor controllably connected between a first reference node and the ground terminal under the control of the voltage of the drain of the first transistor; a third transistor controllably connected between the voltage output terminal and the emitter of a fourth transistor under the control of the voltage of a voltage dividing node of a first voltage dividing branch; the fourth transistor controllably connected between the collector of the third transistor and a voltage dividing node of a second voltage dividing branch under the control of the voltage of the first reference node. Beneficial effects: Through the above-mentioned state detection circuit for a dimmable light, precise control of the lamp is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of detection of dimmable lights, and particularly relates to a circuit for detecting the state of a dimmable light. Background Art

[0002] At present, the dimming methods of LED dimming devices on the market are becoming increasingly rich. For example, DALI dimming, DMX dimming, 0 / 1 - 10V dimming, resistance dimming, PWM dimming, etc. have all emerged one after another. In the application of LED lights on the market, group control and scene control involve the control of a certain number of lights. For example, DALI dimming can control 16 groups of lights and 16 scenes respectively.

[0003] Existing technical problems: For some building lighting controls, such as in shopping malls and supermarkets, the lighting controller cannot detect the operating state of the lights and feedback it to the host to achieve precise control of the lights. The original dimming degree of the dimmable lights was at least 1%. Now, there are electronic products with a dimming depth of one-thousandth or even one-ten-thousandth. However, the original technology cannot detect the dimming depth below one-thousandth, and the accuracy of dimming detection is relatively low. Summary of the Invention

[0004] The purpose of the present invention is to provide a circuit for detecting the state of a dimmable light to solve the above technical problems.

[0005] The technical problems solved by the present invention can be achieved by adopting the following technical solutions:

[0006] A circuit for detecting the state of a dimmable light, comprising:

[0007] A first transistor (Q13), controllably connected between a voltage output terminal (VOUT) and a ground terminal (GND) under the control of the voltage at the negative electrode (LED-) of an LED light;

[0008] A second transistor (Q11), controllably connected between a first reference node (N1) and the ground terminal (GND) under the control of the drain voltage of the first transistor (Q13);

[0009] A third transistor (Q7), controllably connected between the voltage output terminal (VOUT) and the emitter of a fourth transistor (Q9) under the control of the voltage at a voltage dividing node (N3) of a first voltage dividing branch, the first voltage dividing branch being connected between the positive electrode (LED+) of the LED light and the ground terminal (GND);

[0010] The fourth transistor (Q9) is controllably connected between the collector of the third transistor (Q7) and a voltage division node (N2) of a second voltage division branch under the control of the voltage at the first reference node (N1). The second voltage division branch is connected between the voltage output terminal (VOUT) and the ground terminal (GND). The voltage division node (N2) of the second voltage division branch outputs a dimming state detection signal as a detection signal output terminal.

[0011] Preferably, the voltage division node (N2) of the second voltage division branch inputs the dimming state detection signal into a single-chip microcomputer for signal processing, and the single-chip microcomputer feeds back the state of the LED lamp to a host to control the LED lamp.

[0012] Preferably, a first resistor (R18) is connected between the drain of the first transistor (Q13) and the voltage output terminal (VOUT), a first diode (D6) is connected between the gate and the negative electrode (LED-) of the LED lamp, the source of the first transistor (Q13) is connected to the ground terminal (GND), a second capacitor (C11) and a fifth resistor (R35) are connected between the gate of the first transistor (Q13) and the ground terminal (GND), and the second capacitor (C11) and the fifth resistor (R35) are in parallel.

[0013] Preferably, a third resistor (R25) is connected between the collector of the second transistor (Q11) and the first reference node (N1), the base of the second transistor (Q11) is connected to the drain of the first transistor (Q13), the emitter of the second transistor (Q11) is connected to the ground terminal (GND), a fourth resistor (R16) is connected between the first reference node (N1) and the voltage output terminal (VOUT), and the third resistor (R25) and the fourth resistor (R16) are in series.

[0014] Preferably, the emitter of the third transistor (Q7) is connected to the voltage output terminal (VOUT), a second resistor (R14) is connected between the base of the third transistor (Q7) and the voltage division node (N3) of the first voltage division branch, a first capacitor (C9) is connected between the voltage division node (N3) of the first voltage division branch and the ground terminal (GND), a seventh resistor (R36) and a second diode (D3) are connected between the voltage division node (N3) of the first voltage division branch and the positive input terminal (LED+) of the LED lamp, the seventh resistor (R36) and the second diode (D3) are in series, an eighth resistor (R28) is connected between the first voltage division node (N3) of the first voltage division branch and the ground terminal (GND), and the collector of the third transistor (Q7) is connected to the emitter of the fourth transistor (Q9).

[0015] Preferably, the base of the fourth transistor (Q9) is connected to the first reference node (N1), a third resistor (R27) is connected between the collector of the fourth transistor (Q9) and the voltage division node (N2) of the second voltage division branch, a sixth resistor (R21) is connected between the voltage division node (N2) of the second voltage division branch and the voltage output terminal (VOUT), and a ninth resistor (R31) is connected between the voltage division node (N2) of the second voltage division branch and the ground terminal (GND).

[0016] Preferably, it further includes a power supply dimming circuit, and the power supply dimming circuit includes:

[0017] A transformer (T2), including a primary winding of the transformer (T2) and a secondary winding of the transformer (T2);

[0018] An inductor (L5) is connected between a fifth reference node (N5) and the first end (1) of the primary winding of the transformer (T2);

[0019] A third capacitor (C18) is connected between the second end (2) of the primary winding of the transformer (T2) and the ground terminal (GND).

[0020] Preferably, the power supply dimming circuit further includes:

[0021] A third diode (D7) is connected between the first end (3) of the secondary winding of the transformer (T2) and the positive electrode (LED+) of the LED lamp;

[0022] The second end (4) of the secondary winding of the transformer (T2) is connected to the ground terminal (GND);

[0023] A fourth diode (D9) is connected between the third end (5) of the secondary winding of the transformer (T2) and the negative electrode of the third diode (D7);

[0024] A fourth capacitor (C19) is connected between the negative electrode of the fourth diode (D9) and the ground terminal (GND).

[0025] Preferably, the power supply dimming circuit further includes:

[0026] A fifth transistor (Q1) is controllably connected between a power supply input terminal (HV) and the fifth reference node (N5) under the action of a first gate control voltage (VG1);

[0027] A sixth transistor (Q4) is controllably connected between the fifth reference node (N5) and the ground terminal (GND) under the action of a second gate control voltage (VG2);

[0028] A seventh transistor (Q5) is controllably connected between the negative electrode (LED-) of the LED lamp and the ground terminal (GND).

[0029] Beneficial effects: Through the above-mentioned dimming lamp state detection circuit, the detection signal is sent from the voltage division node of the second voltage division branch to the single-chip microcomputer for signal processing, and the state of the LED lamp is fed back to a host for processing, so that the system host can respond in time and report the fault state of the LED lamp, achieving high-precision detection of the dimming state. Description of the Drawings

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the structures shown in these drawings.

[0031] Figure 1 It is a schematic topological structure diagram of a dimming state detection circuit for an LED lamp of the present invention;

[0032] Figure 2 It is a schematic structural diagram of a power supply dimming circuit for an LED lamp of the present invention.

[0033] Reference numerals: Q13, the first transistor; Q11, the second transistor; Q7, the third transistor; Q9, the fourth transistor; C9, the first capacitor; C11, the second capacitor; C18, the third capacitor; C19, the fourth capacitor; D6, the first diode; D3, the second diode; D7, the third diode; D9, the fourth diode; R18, the first resistor; R14, the second resistor; R27, the third resistor; R31, the ninth resistor; N1, the first reference node; N3, the voltage division node of the first voltage division branch; N2, the voltage division node of the second voltage division branch; N4, the fourth reference node; LED+, the positive electrode of the LED lamp; LED-, the negative electrode of the LED lamp; HV, the voltage input terminal; VOUT, the voltage output terminal; VG1, the first gate control signal terminal; VG2, the second gate control signal terminal. Detailed Embodiments

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0035] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other.

[0036] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but it is not intended to limit the present invention.

[0037] As Figure 1 shown, the present invention provides a dimmable lamp state detection circuit, including:

[0038] A first transistor Q13 is controllably connected between a voltage output terminal VOUT and a ground terminal GND under the control of a signal of the negative electrode LED- of an LED lamp;

[0039] A second transistor Q11 is controllably connected between a first reference node N1 and the ground terminal GND under the control of the drain voltage of the first transistor Q13;

[0040] A third transistor Q7 is controllably connected between the voltage output terminal VOUT and the emitter of a fourth transistor Q9 under the control of the voltage of a voltage dividing node N3 of a first voltage dividing branch, and the first voltage dividing branch is connected between the positive electrode LED+ of the LED lamp and the ground terminal GND;

[0041] A fourth transistor Q9 is controllably connected between the collector of the third transistor Q7 and a voltage dividing node N2 of a second voltage dividing branch under the control of the first reference node N1. The second voltage dividing branch is connected between the voltage output terminal VOUT and the ground terminal GND, and the voltage dividing node N2 of the second voltage dividing branch outputs a dimming state detection signal as a detection signal output terminal. The dimming state of the LED lamp is accurately detected through the above dimmable lamp state detection circuit.

[0042] Preferably, a first resistor R18 is connected between the drain of the first transistor Q13 and the voltage output terminal VOUT, a first diode D6 is connected between the gate and the positive electrode LED+ of the LED lamp, the source of the first transistor Q13 is connected to the ground terminal GND, and a second capacitor C11 and a fifth resistor R35 are connected between the gate of the first transistor Q13 and the ground terminal GND, and the second capacitor C11 and the fifth resistor R35 are in parallel.

[0043] Preferably, a third resistor R25 is connected between the collector of the second transistor Q11 and the first reference node N1, the base of the second transistor Q11 is connected to the drain of the first transistor Q13, the emitter of the second transistor Q11 is connected to the ground terminal GND, a fourth resistor R16 is connected between the first reference node N1 and the voltage output terminal VOUT, and the third resistor R25 and the fourth resistor R16 are in series.

[0044] Preferably, the emitter of the third transistor Q7 is connected to the voltage output terminal VOUT. A second resistor R14 is connected between the base of the third transistor Q7 and the voltage division node N3 of the first voltage division branch. A first capacitor C9 is connected between the voltage division node N3 of the first voltage division branch and the ground terminal GND. A seventh resistor R36 and a second diode D3 are connected between the voltage division node N3 of the first voltage division branch and the positive input terminal LED+ of the LED lamp. The seventh resistor R36 and the second diode D3 are connected in series. An eighth resistor R28 is connected between the first voltage division node N3 of the first voltage division branch and the ground terminal GND. The collector of the third transistor Q7 is connected to the emitter of the fourth transistor Q9.

[0045] Preferably, the base of the fourth transistor Q9 is connected to the first reference node N1. A third resistor R27 is connected between the collector of the fourth transistor Q9 and the voltage division node N2 of the second voltage division branch. A sixth resistor R21 is connected between the voltage division node N2 of the second voltage division branch and the voltage output terminal VOUT. A ninth resistor R31 is connected between the voltage division node N2 of the second voltage division branch and the ground terminal GND.

[0046] Generally, the LED lamp is used as a load and the object to be tested. The possible operating states during its operation include: full load, dimming, and open circuit state. In a preferred embodiment, when the LED lamp is in the full load state, the gate voltage of the first transistor Q13 is 0, the first transistor Q13 is turned off, the second transistor Q11 is turned on. When at full load, the voltage of the positive electrode LED+ of the LED lamp will be higher than the output voltage, the third transistor Q7 and the seventh transistor Q5 are turned off, and the voltage on the voltage division node N2 of the second voltage division branch is the voltage division of the sixth resistor R21 and the ninth resistor R31.

[0047] As Figure 2 shown, further, in the above dimmer state detection circuit, there is also a power supply dimming circuit, and this power supply dimming circuit includes:

[0048] A transformer T2, including a primary winding of the transformer T2 and a secondary winding of the transformer T2; An inductor L5 is connected between a fourth reference node N4 and the first end 1 of the primary winding of the transformer T2; A third capacitor C18 is connected between the second end 2 of the primary winding of the transformer T2 and the ground terminal GND.

[0049] Preferably, the power supply dimming circuit further includes:

[0050] A third diode D7 is connected between the first end 3 of the secondary winding of the transformer T2 and the positive electrode LED+ of the LED lamp; The second end 4 of the secondary winding of the transformer T2 is connected to the ground terminal GND;

[0051] A fourth diode D9 is connected between the third terminal 5 of the secondary winding of the transformer T2 and the cathode of the third diode D7; a fourth capacitor C19 is connected between the cathode of the fourth diode D9 and the ground terminal GND.

[0052] Preferably, the power supply dimming circuit further includes: a fifth transistor Q1 controllably connected between a power input terminal HV and a fourth reference node N4 under the action of a control signal input at a first gate control signal terminal VG1; a sixth transistor Q4 controllably connected between the fourth reference node N4 and the ground terminal GND under the action of a control signal input at a second gate control signal terminal VG2; a seventh transistor Q5 controllably connected between the negative electrode LED- of the LED lamp and the ground terminal GND. Among them, the above-mentioned fifth transistor Q1 and sixth transistor Q4 are MOS transistors.

[0053] This power supply dimming circuit uses PWM chopper dimming, and controls the duty cycle of the output MOS transistor through a single-chip microcomputer for dimming. When the seventh transistor Q5 is turned on, the drain voltage of the seventh transistor Q5 is 0. When the seventh transistor Q5 is turned off, under the action of the LED lamp, there is a potential difference of 2V across the LED lamp. When the gates of the fifth transistor Q1 and the sixth transistor Q4 are PWM dimming signals, the voltage waveforms of the above transistors are PWM waveforms that are opposite to each other (i.e., in antiphase, with a phase difference of 180° between the two waveforms). The waveform measured at the positive electrode of the LED lamp is a pulse waveform. When the load of the LED lamp is smaller, the duty cycle of the pulse waveform is smaller. Through the above LED lamp power supply dimming circuit, stable power supply and precise dimming of the LED lamp are achieved.

[0054] In a certain preferred embodiment, when the LED lamp is in the dimming state, the gate voltage of the first transistor Q13 presents a high level after being rectified and filtered by the inductor and capacitor in the above circuit. Then the first transistor Q13 is turned on and the second transistor Q11 is turned off (equivalent to the switch being disconnected). Since the second transistor Q11 is turned off, regardless of whether the seventh transistor Q5 is turned on or off, the third transistor Q7 is always turned off. At this time, the voltage of the voltage division node N2 of the second voltage division branch is still the voltage division of the sixth resistor R21 and the ninth resistor R31 on the second voltage division branch.

[0055] In a preferred embodiment, when the LED lamp is in an open-circuit state, since the duty cycle of the pulse waveform of the positive electrode LED+ of the LED lamp is relatively low, the base terminal voltage of the third transistor Q7 is lower than the voltage of the voltage output terminal VOUT through the voltage division adjustment of the seventh resistor R36 and the eighth resistor R28, so that the third transistor Q7 is turned on. Since the LED lamp is open-circuited, the gate voltage of the first transistor Q13 is 0 and it is cut off, and the second transistor Q11 is turned on. At this time, the seventh transistor Q5 is also turned on. Therefore, the voltage across both ends of the voltage division node N2 of the second voltage division branch is the voltage division of the parallel connection of the third resistor R27 and the sixth resistor R21 and then the ninth resistor R31. When the LED lamp is open-circuited, the voltage of the voltage division node N2 of the second voltage division branch is higher than the voltage when the LED lamp is in PWM dimming and full load.

[0056] Combined with Figure 1 、 Figure 2 and the above circuit dimming and dimming state detection and control principle, it can be seen that by designing the above triodes Q7, Q9, Q11 and small-signal MOS tubes Q1, Q4, Q5, Q13 into a dimmable lamp state detection circuit, various states of the power supply under no-load, full-load and dimming states can be detected, including the open circuit and short circuit of the lamp. In some applications that need to control the states of multiple groups of lamps, when a certain road lamp has a fault such as open circuit or short circuit, this circuit can accurately detect the lamp fault situation and report the lamp fault information.

[0057] After the above detection process of the dimming state of the LED lamp, the detection circuit generates a dimming state detection signal and inputs it to a single-chip microcomputer for signal processing through the voltage division node N2 of the second voltage division branch. The single-chip microcomputer feeds back the state of the LED lamp to a host to control the above LED lamp. By analyzing and processing the state detection signal by the single-chip microcomputer and inputting the processing result into the above host for control, the automatic and intelligent control of the optical adjustment of the LED lamp is realized, significantly reducing the manual intervention and its additional costs when the LED lamp runs abnormally. It is economical and convenient. Through the above design, the lamp fault detection with a dimming depth of one ten-thousandth can be realized, improving the accuracy of the detection of the real-time operation state of the dimming function of the LED lamp, and the accuracy is high.

[0058] In summary, the advantageous features of the present invention are: through the above LED lamp power supply dimming circuit, the stable power supply and accurate dimming of the LED lamp are realized; through the above dimmable lamp state detection circuit, the detection signal is sent from the voltage division node of the second voltage division branch to the single-chip microcomputer for signal processing, and the state of the LED lamp is fed back to the host for processing, so that the system host can respond in time and report the lamp fault state, and realize the high-precision detection of the dimming ability to achieve accurate control.

[0059] The above are only the preferred embodiments of the present invention, and do not limit the implementation manners and protection scope of the present invention. For those skilled in the art, it should be realized that all the equivalent replacements and obvious changes made by using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A dimmable lamp state detection circuit, characterized in that, Comprising: A first transistor (Q13), controllably connected between a voltage output terminal (VOUT) and a ground terminal (GND) under the control of the voltage at the negative electrode (LED-) of an LED lamp; A second transistor (Q11), controllably connected between a first reference node (N1) and the ground terminal (GND) under the control of the drain voltage of the first transistor (Q13), and a fourth resistor (R16) is connected between the first reference node (N1) and the voltage output terminal (VOUT); A third transistor (Q7), controllably connected between the voltage output terminal (VOUT) and the emitter of a fourth transistor (Q9) under the control of the voltage at a voltage dividing node (N3) of a first voltage dividing branch, the first voltage dividing branch being connected between the positive electrode (LED+) of the LED lamp and the ground terminal (GND), and an eighth resistor (R28) is connected between the voltage dividing node (N3) of the first voltage dividing branch and the ground terminal (GND); The fourth transistor (Q9), controllably connected between the collector of the third transistor (Q7) and a voltage dividing node (N2) of a second voltage dividing branch under the control of the voltage at the first reference node (N1), the second voltage dividing branch being connected between the voltage output terminal (VOUT) and the ground terminal (GND), the voltage dividing node (N2) of the second voltage dividing branch outputs a dimming state detection signal as a detection signal output terminal, and a sixth resistor (R21) is connected between the voltage dividing node (N2) of the second voltage dividing branch and the voltage output terminal (VOUT); A first resistor (R18) is connected between the drain of the first transistor (Q13) and the voltage output terminal (VOUT), the gate of the first transistor (Q13) is connected to the cathode of a first diode (D6), the anode of the first diode (D6) is connected to the negative electrode (LED-) of the LED lamp, and the source of the first transistor (Q13) is connected to the ground terminal (GND).

2. The dimmable lamp state detection circuit according to claim 1, characterized in that, The voltage dividing node (N2) of the second voltage dividing branch inputs the dimming state detection signal into a single-chip microcomputer for signal processing, and the single-chip microcomputer feeds back the state of the LED lamp to a host to control the LED lamp.

3. The dimmable lamp state detection circuit according to claim 1, characterized in that, A second capacitor (C11) and a fifth resistor (R35) are connected in parallel between the gate of the first transistor (Q13) and the ground terminal (GND).

4. The dimmable lamp state detection circuit according to claim 1, characterized in that, A third resistor (R25) is connected between the collector of the second transistor (Q11) and the first reference node (N1), the base of the second transistor (Q11) is connected to the drain of the first transistor (Q13), the emitter of the second transistor (Q11) is connected to the ground terminal (GND), and the third resistor (R25) and the fourth resistor (R16) are connected in series.

5. The dimmable lamp state detection circuit according to claim 1, characterized in that, The emitter of the third transistor (Q7) is connected to the voltage output terminal (VOUT). A second resistor (R14) is connected between the base of the third transistor (Q7) and the voltage division node (N3) of the first voltage division branch. A first capacitor (C9) is connected between the voltage division node (N3) of the first voltage division branch and the ground terminal (GND). A seventh resistor (R36) and a second diode (D3) are connected between the voltage division node (N3) of the first voltage division branch and the positive electrode (LED+) of the LED lamp. The seventh resistor (R36) is connected to the cathode of the second diode (D3), and the anode of the second diode (D3) is connected to the positive input terminal (LED+) of the LED lamp. The collector of the third transistor (Q7) is connected to the emitter of the fourth transistor (Q9).

6. The dimmable lamp state detection circuit according to claim 1, characterized in that, The base of the fourth transistor (Q9) is connected to the first reference node (N1). A third resistor (R27) is connected between the collector of the fourth transistor (Q9) and the voltage division node (N2) of the second voltage division branch. A ninth resistor (R31) is connected between the voltage division node (N2) of the second voltage division branch and the ground terminal (GND).

7. The dimmable lamp state detection circuit according to claim 1, characterized in that, It further includes a power supply dimming circuit, and the power supply dimming circuit includes: A transformer (T2), including a primary winding of the transformer (T2) and a secondary winding of the transformer (T2); An inductor (L5), connected between a fourth reference node (N4) and the first end of the primary winding of the transformer (T2); A third capacitor (C18), connected between the second end of the primary winding of the transformer (T2) and the ground terminal (GND); A third diode (D7), the positive electrode of the third diode (D7) is connected to the first end of the secondary winding of the transformer (T2), and the negative electrode of the third diode (D7) is connected to the positive electrode (LED+) of the LED lamp; The second end of the secondary winding of the transformer (T2) is connected to the ground terminal (GND); A fourth diode (D9), the positive electrode of the fourth diode (D9) is connected to the third end of the secondary winding of the transformer (T2), and the negative electrode of the fourth diode (D9) is connected to the negative electrode of the third diode (D7); A fourth capacitor (C19), connected between the negative electrode of the fourth diode (D9) and the ground terminal (GND); A fifth transistor (Q1), controllably connected between a power supply input terminal (HV) and the fourth reference node (N4) under the action of a first gate control voltage (VG1); A sixth transistor (Q4), controllably connected between the fourth reference node (N4) and the ground terminal (GND) under the action of a second gate control voltage (VG2); A seventh transistor (Q5), controllably connected between the negative electrode (LED-) of the LED lamp and the ground terminal (GND); The first gate control voltage (VG1) and the second gate control voltage (VG2) are PWM dimming signals.

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