Ballast abnormity protection circuit

Abstract

The utility model relates to the technical field of ballasts, in particular to a ballast abnormity protection circuit, which respectively samples filament current signals and ballast output voltage signals by arranging a current protection circuit and a voltage protection circuit, and outputs the output voltage signals through the design of internal logic and time sequence of the protection circuit. The lamp tube monitoring circuit can monitor and effectively protect abnormal states such as a rectification effect caused by short circuit, open circuit, tube separation, filament breakage, overload, service life, gas leakage and filament single-end inactivation of a ballast and a lamp tube, retains the original protection function of a chip, additionally designs the lamp tube monitoring circuit, compensates for the short circuit of the original protection function of the chip, and improves the reliability of the lamp tube monitoring circuit. And more comprehensive abnormal state protection can be carried out on the ballast.

Description

Technical Field

[0001] The utility model relates to the technical field of ballasts, in particular to an abnormal protection circuit for a ballast. Background Art

[0002] The ballasts currently designed generally use ballast chips to protect against abnormal conditions. However, there are eight types of abnormalities in ballasts and lamps: short circuit, open circuit, tube detachment, broken filament, overload, end of life, gas leakage, and rectification effect caused by single-end inactivation of the filament. In addition, the working states of the ballast are diverse: high-frequency preheating state, variable frequency triggering state, and steady current state at the working frequency. In the high-frequency preheating state, the lamp is not conducting, and the circuit is an LC series resonant circuit; in the steady current state at the working frequency, the lamp on-resistance presents a negative resistance characteristic, and the circuit is an LRC series-parallel resonance. The electrical parameters of various states vary greatly, and the lamp trigger voltage is 5 to 10 times the working voltage. The chip protection measures cannot cover all abnormal problems and can only be effective for some abnormal states. For example, when detecting current, the MOS tube on-resistance is used to measure the current by measuring the on-voltage, and it is difficult to achieve protection that takes into account various states. Therefore, a technology that can more comprehensively monitor abnormal states and more reliably protect ballasts from abnormalities is urgent and necessary. Utility Model Content

[0003] In view of this, the purpose of the present invention is to provide a ballast abnormality protection circuit to solve the problem that the existing method cannot provide comprehensive and reliable abnormality protection for the ballast.

[0004] Based on the above purpose, the utility model provides a ballast abnormality protection circuit, which is used to shut down the ballast drive circuit in time to avoid damage when an abnormality is found in the lamp tube, and the ballast abnormality protection circuit includes:

[0005] A current protection circuit, comprising: a sampling transformer, a first rectifier diode, a sampling resistor, a first voltage-stabilizing diode, a first transistor, a second voltage-stabilizing diode and a first execution circuit, wherein the execution circuit comprises a first dual-triode interlocking circuit or a first unidirectional thyristor, the sampling transformer is used to sample the filament current of the lamp tube, the sampling resistor is used to convert the current signal into a voltage signal, the first voltage-stabilizing diode and the second voltage-stabilizing diode are respectively arranged at the output end of the sampling resistor and the output end of the first transistor, and are used to set a threshold to identify the signal and prevent malfunction, the first dual-triode interlocking circuit comprises two switching transistors that control each other's base, the input end of the first dual-triode interlocking circuit is connected to the output of the second voltage-stabilizing diode, and the output end of the first dual-triode interlocking circuit is connected to the power input end of the ballast chip;

[0006] A voltage protection circuit comprises a second rectifier diode, a third voltage regulator diode and a second execution circuit, wherein the second execution circuit comprises a second dual triode interlocking circuit or a second unidirectional thyristor, wherein the voltage protection circuit samples the voltage from the lamp tube, and inputs the voltage into the second dual triode interlocking circuit after passing through the second rectifier diode and the third voltage regulator diode, wherein the output end of the second dual triode interlocking circuit is connected in parallel with the output end of the first dual triode interlocking circuit, and is connected to the power input end of the ballast chip.

[0007] Preferably, the power supply of the ballast chip includes a trickle circuit and a charge pump, the trickle circuit includes a capacitor and an electrolytic capacitor in parallel, the output of the trickle circuit is connected to the power input port of the ballast chip and the charge pump, the charge pump includes a pair of diodes and a capacitor, and the output ends of the first dual-triode interlocking circuit and the second dual-triode interlocking circuit are both connected to the output end of the trickle circuit.

[0008] Preferably, the first dual-transistor interlocking circuit and the second dual-transistor interlocking circuit each include two complementary transistors, one of which is an NPN transistor and the other is a PNP transistor, the base of the NPN transistor is connected to the protection input, its emitter is grounded, and its collector is connected to the base of the PNP transistor, the collector of the PNP transistor is connected to the base of the NPN transistor, and the emitter of the PNP transistor is connected to the power input terminal of the ballast chip, and anti-interference capacitors are connected between the base and emitter of the two switching transistors.

[0009] Preferably, the threshold voltage of the first zener diode is 2.4V-10V, and the threshold voltage of the second zener diode is 3V-10V.

[0010] Preferably, the output ends of the voltage protection circuit and the current protection circuit are connected in parallel and then connected to the power input end of the ballast chip through a light emitting diode.

[0011] Preferably, the first pin of the lamp is connected to the output end of the ballast, the second pin and the third pin of the lamp are directly connected to a resonant capacitor, and the sampling transformer of the current protection circuit is arranged between the second pin and the third pin.

[0012] The beneficial effects of the utility model are as follows: by sampling the ballast output voltage signal and the lamp filament current signal respectively through the voltage protection circuit and the current protection circuit, and through the internal timing and logic design of the protection circuit, the ballast and the lamp can be monitored for abnormal conditions such as short circuit, open circuit, tube disconnection, filament breakage, overload, end of life, gas leakage and rectification effect caused by single-ended deactivation of the filament and other abnormal conditions and effectively protect them. While retaining the original protection function of the chip, this solution separately designs a lamp tube monitoring circuit, which can provide more comprehensive abnormal condition protection for the ballast. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only for the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0014] Figure 1 The ballast driving part, the lamp tube part and the power supply part in the principle diagram of the ballast abnormal protection circuit of the embodiment of the utility model;

[0015] Figure 2 This is a schematic diagram of a voltage protection circuit according to an embodiment of the utility model;

[0016] Figure 3 This is a schematic diagram of a current protection circuit according to an embodiment of the utility model;

[0017] Figure 4 Another current protection circuit schematic diagram of an embodiment of the utility model;

[0018] Figure 5 This is another packaging schematic diagram of the D5 and D6 diodes according to an embodiment of the utility model. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments.

[0020] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0021] like Figure 1As shown, the embodiment of the specification provides a ballast abnormality protection circuit, which has a lamp state monitoring function and a protection execution function, and is used to timely shut down the ballast driving circuit when the lamp is abnormal to avoid damage. The lamp state monitoring circuit is electrically connected to the lamp LAMP, and the protection execution circuit is electrically connected to the ballast driving chip U. This embodiment does not need to change the circuit connection structure between the ballast chip U and the lamp LAMP, but adds a current protection circuit and a voltage protection circuit to the original ballast circuit, wherein:

[0022] Current protection circuits, such as Figure 3 As shown, it includes: a sampling transformer L3, a first rectifier diode PD3, a sampling resistor PR10, a first voltage regulator diode PD4, a first transistor Q1, a second voltage regulator diode PD5 and a first dual transistor interlocking circuit, the sampling transformer L3 is used to sample the current at the lamp tube, the sampling resistor PR10 is used to convert the current signal into a voltage signal, the first voltage regulator diode PD4 and the second voltage regulator diode PD5 are respectively arranged at the output end of the sampling resistor PR10 and the output end of the first transistor Q1, and are used to set the threshold.

[0023] Voltage protection circuits such as Figure 2 As shown, it includes a second rectifier diode PD1, a third voltage regulator diode PD2 and a second dual triode interlocking circuit. The voltage protection circuit samples the voltage from the lamp tube LAMP, and inputs the voltage into the second dual triode interlocking circuit after passing through the second rectifier diode PD1 and the third voltage regulator diode PD2. The output end of the second dual triode interlocking circuit is connected to the power input end of the ballast chip U.

[0024] As an implementation method, a unidirectional thyristor can be used in the current protection circuit and the voltage protection circuit to replace the double triode interlocking circuit, such as Figure 4 As shown in the figure, a unidirectional thyristor Q3 is used, and specifically, the MCR100-8 unidirectional thyristor can be selected.

[0025] As an embodiment, the power supply of the ballast chip U includes a trickle circuit and a charge pump, the trickle circuit includes a capacitor C2 and an electrolytic capacitor E2 connected in parallel, the output of the trickle circuit is connected to the power input port of the ballast chip U and the charge pump, the charge pump includes a diode D5 and a capacitor C5, and the output ends of the first dual triode interlocking circuit and the second dual triode interlocking circuit are both connected to the output end of the trickle circuit, such as Figure 1 As shown in Figure 1, diodes D5 and D6 can be packaged separately or as Figure 5 Packaged together as shown in .

[0026] The above-mentioned current protection circuit can detect abnormal conditions such as broken wire and open circuit in the ballast circuit, and the voltage protection circuit can detect abnormal conditions such as short circuit, open circuit, end of life, rectification in the ballast circuit. In addition, through the combination of the current protection circuit and the voltage protection circuit, the leakage and overload conditions of the ballast can also be detected and protected.

[0027] As an implementation mode, the first dual-transistor interlocking circuit and the second dual-transistor interlocking circuit each include two complementary transistors, one of which is an NPN transistor and the other is a PNP transistor, the base of the NPN transistor is connected to the protection input, its emitter is grounded, and its collector is connected to the base of the PNP transistor, the collector of the PNP transistor is connected to the base of the NPN transistor, and the emitter of the PNP transistor is connected to the power input terminal of the ballast chip, and anti-interference capacitors are connected between the base and emitter of the two switching transistors.

[0028] When the ballast is working normally, the ballast chip U normally performs the preheating start, frequency control and some abnormal protection functions of the ballast. At this time, the current protection circuit and the voltage protection circuit are both set with voltage regulator diodes as thresholds, so they will not act and will not affect the operation of the ballast. When abnormal conditions such as broken wire, open circuit, tube detachment, gas leakage, overload, etc. occur, one of the two abnormal characteristic quantities will appear: the voltage is too high or the filament current disappears.

[0029] These two characteristics are identified by the voltage protection circuit and the current protection circuit respectively, and then the chip working voltage is turned off and locked by the execution circuit. Only after the fault is eliminated and the power is turned on again can normal operation be restored.

[0030] Specifically, during normal operation, the sampling transformer L3 in the current protection circuit samples the filament current signal, which is converted into a voltage signal after passing through the first rectifier diode PD3, the sampling resistor PR10 and the capacitor C1. This voltage exceeds the threshold value of the first voltage regulator diode PD4 and turns on PD4, the collector C of the transistor Q1 has a low voltage, the first dual transistor interlocking circuit does not operate, and the ballast works normally.

[0031] When the filament current disappears, it means that the filament is broken, the tube is detached, or the lamp holder has poor contact. The sampling transformer L3 in the current protection circuit cannot collect the filament current signal. The voltage signal converted after the first rectifier diode PD3, the sampling resistor PR10 and the capacitor C1 is zero, PD4 is cut off, the collector C of the transistor Q1 is high, the first double transistor interlocking circuit is activated, OUT2 is connected to the ground, and the working voltage VCC1 of the driver chip is pulled to zero through LED2 and PR16. The ballast stops working and the broken wire protection is realized. And the circuit is locked through the double transistor interlocking circuit. The trickle current keeps LED2 emitting light to indicate the protection lock state.

[0032] The position of L3 is between pins 23 of the lamp tube, which can effectively monitor and reliably protect the broken wires at both the upper and lower parts of the lamp tube.

[0033] When the lamp connected to the ballast encounters abnormal conditions such as short circuit, open circuit, end of life, rectification, leakage, overload, etc., the abnormal voltage input voltage protection circuit generated is higher than the threshold voltage of the third voltage stabilizing diode PD2, which will trigger the transistor PQ1, turn on the collector and emitter of PQ1, and directly introduce the input power of the ballast chip U to the ground, so that the ballast chip U will not start, thereby protecting the ballast, and through the action of the switching transistor PQ2, the circuit is locked, and the ballast chip U will not start after an abnormal condition occurs to prevent device damage or other unsafe conditions.

[0034] As an implementation mode, the first voltage zener diode and the second voltage zener diode are voltage zener diodes or bidirectional trigger diodes, the threshold voltage of the first voltage zener diode is 2.4V-10V, preferably 2.4V, and the threshold voltage of the second voltage zener diode is 3-10V, preferably 7.5V. Generally, when the filament of the lamp tube is normal, the current signal generated by the filament current converts the voltage signal to exceed 2.4V, and the broken wire protection does not work. When the filament of the lamp tube is broken, the current signal generated by the filament current converts the voltage signal to 0V, and the broken wire protection is activated to achieve protection.

[0035] As an implementation mode, after the output ends of the voltage protection circuit and the current protection circuit are connected in parallel, a light-emitting diode LED2 is connected in reverse, and is connected to the power input end of the ballast chip through the light-emitting diode LED2. That is, when the ballast has an abnormality, the light-emitting diode LED2 will light up to serve as a prompt.

[0036] As an implementation mode, the first pin of the lamp tube LAMP is connected to the output end of the ballast chip U, the second pin and the third pin of the lamp tube LAMP are directly connected to the capacitor C8, and the sampling transformer L3 of the current protection circuit is arranged between the second pin and the third pin. This arrangement can effectively monitor the broken wires at both the upper and lower parts of the lamp tube.

[0037] The ballast abnormal protection circuit provided in this embodiment can monitor the abnormal conditions of the ballast and lamp tube, such as short circuit, open circuit, tube disconnection, filament breakage, overload, end of life, gas leakage, and rectification effect caused by single-ended deactivation of the filament, and provide effective protection, and has been applied to new ballasts.

[0038] While retaining the original protection function of the chip, this solution also designs a lamp tube monitoring circuit. It has been proven that it can identify the above 8 abnormal conditions and is effective in practical application protection.

[0039] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present invention (including the claims) is limited to these examples. Under the concept of the present invention, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity.

[0040] The utility model is intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the utility model should be included in the scope of protection of the utility model.

Claims

1. A ballast abnormality protection circuit, used to shut down the ballast drive circuit in time to avoid damage when an abnormality is found in the lamp tube, characterized in that: The ballast abnormality protection circuit comprises: A current protection circuit, comprising: a sampling transformer, a first rectifier diode, a sampling resistor, a first voltage-stabilizing diode, a first transistor, a second voltage-stabilizing diode and a first execution circuit, wherein the execution circuit comprises a first dual-triode interlocking circuit or a first unidirectional thyristor, the sampling transformer is used to sample the filament current of the lamp tube, the sampling resistor is used to convert the current signal into a voltage signal, the first voltage-stabilizing diode and the second voltage-stabilizing diode are respectively arranged at the output end of the sampling resistor and the output end of the first transistor, and are used to set a threshold to identify the signal and prevent malfunction, the first dual-triode interlocking circuit comprises two switching transistors that control each other's base, the input end of the first dual-triode interlocking circuit is connected to the output of the second voltage-stabilizing diode, and the output end of the first dual-triode interlocking circuit is connected to the power input end of the ballast chip; A voltage protection circuit comprises a second rectifier diode, a third voltage regulator diode and a second execution circuit, wherein the second execution circuit comprises a second dual triode interlocking circuit or a second unidirectional thyristor, wherein the voltage protection circuit samples the voltage from the lamp tube, and inputs the voltage into the second dual triode interlocking circuit after passing through the second rectifier diode and the third voltage regulator diode, wherein the output end of the second dual triode interlocking circuit is connected in parallel with the output end of the first dual triode interlocking circuit, and is connected to the power input end of the ballast chip.

2. The ballast abnormality protection circuit according to claim 1, characterized in that: The power supply of the ballast chip includes a trickle circuit and a charge pump. The trickle circuit includes a capacitor and an electrolytic capacitor in parallel. The output of the trickle circuit is connected to the power input port of the ballast chip and the charge pump. The charge pump includes a pair of diodes and a capacitor. The output ends of the first dual-triode interlocking circuit and the second dual-triode interlocking circuit are both connected to the output end of the trickle circuit.

3. The ballast abnormality protection circuit according to claim 1, characterized in that: The first dual-triode interlocking circuit and the second dual-triode interlocking circuit each include two complementary transistors, one of which is an NPN transistor and the other is a PNP transistor, the base of the NPN transistor is connected to the protection input, its emitter is grounded, and its collector is connected to the base of the PNP transistor, the collector of the PNP transistor is connected to the base of the NPN transistor, and the emitter of the PNP transistor is connected to the power input terminal of the ballast chip, and anti-interference capacitors are connected between the base and emitter of the two switching transistors.

4. The ballast abnormality protection circuit according to claim 1, characterized in that: The threshold voltage of the first Zener diode is 2.4V-10V, and the threshold voltage of the second Zener diode is 3V-10V.

5. The ballast abnormality protection circuit according to claim 1, characterized in that: After the output ends of the voltage protection circuit and the current protection circuit are connected in parallel, they are connected to the power input end of the ballast chip through a light emitting diode.

6. The ballast abnormality protection circuit according to claim 1, characterized in that: The first pin of the lamp is connected to the output end of the ballast, the second pin and the third pin of the lamp are directly connected to a resonant capacitor, and the sampling transformer of the current protection circuit is arranged between the second pin and the third pin.

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