TWI231350B - Protective circuit of electronic ballast - Google Patents

Abstract

This invention relates to a protective circuit of an electronic ballast, especially for the protective circuit of electronic ballast for the fluorescent lamp, mainly comprising a protective loop and an automatic lighting loop after replacement, which can automatically cut off the oscillating loop of the electronic ballast to stop oscillating when extraordinary current state occurs like fluorescent tube being damaged, to avoid the danger of outputting high voltage current. The practice of this invention can assure that the electronic ballast is not damaged or burnt and high voltage current is not outputted, capable of preventing the operator from the danger of electric shock of high voltage current. Moreover, when the damaged or bad fluorescent tube is taken off and replaced with a new one, the tube can be automatically lighted up without the need of switching power supply again.

Description

1231350 V. Description of the invention (1) [Technical field to which the invention belongs] The present invention relates to a protection circuit for an electronic ballast, and more particularly, to a fluorescent lamp electronic having a protection circuit for abnormal current and an automatic lighting function after reset. Protection circuit of ballast. [Prior technology] Generally, the fluorescent tube used in daily life is a closed gas discharge tube. The main gas in the tube is argon, and contains a small amount of neon and krypton. ), Its air pressure is about 0.3% of atmospheric pressure; in addition, the fluorescent tube contains a trace amount of mercury vapor, which accounts for one thousandth of all gases. When the power is turned on and the two ends of the lamp are energized, the on-state current generated by the acceleration of the electrons forms a gas discharge state and causes the fluorescent tube to emit light. The aforementioned gas will form an ion and an electron state. Accelerating motion of the applied electric field collides with gas molecules, including mercury atoms, to convert them into an excited state, which returns to a stable state after releasing 2540 Angstroms of ultraviolet light electromagnetic waves. The fluorescent substance coated on the inner wall of the lamp can absorb this ultraviolet light and emit visible light, which is the light emitted by the fluorescent lamp generally seen. As for the ballast, the stabilizer is a control and adjustment system connected in series with the fluorescent lamp, which itself is composed of an inductor. Since the ballast is connected in series with the fluorescent lamp, an increase in the voltage of the ballast will reduce the voltage of the lamp tube and reduce the current of the lamp tube. The ballast can be used to suppress the rapid change of the lamp current and stabilize the voltage of the lamp tube. The function of current.

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The biggest difference between the traditional ballast and the electronic ballast is that the electronic ballast is high-frequency (20KΗζ-60KΗζ) instantaneous lighting, while the traditional ballast is low-frequency (60Hz), so the output of the electronic ballast is The light is very stable and almost flicker-free, which can effectively protect vision. The basic principle of electronic women's operation is to first rectify AC power of commercial frequency power 50Hz to 60Hz into DC, and then generate high frequency AC power of 20 KHz to 60 KHz through the AC oscillation circuit, and then pass the lighting circuit A current limiting effect is generated, and the lamp is preheated, and the lamp is turned on for about one second. The advantages of electronic ballasts are: 1 · Significant power saving: more than 20% power saving compared with traditional ballasts. 2. Extremely high power factor. Traditional ballast high power type is about 80% to 90%, while electronic ballast is high power which is about 93% to 99%. 3. The light wave is stable and does not flicker: The lighting frequency of the traditional ballast is 60 Hz, and it flickers 12 times per second. The flicker is easy to detect by the naked eye. However, the electronic ballast has a stable output light wave with almost no flicker. ; And, when the power supply voltage changes or the lamp is at low temperature, it is not easy to flicker, which is very helpful for protecting eyesight. 4 · Low audible noise: Compared with traditional stabilizers, it has lower audible sound. 5 · Small volume ’Light weight, the appearance and volume can be changed, and the elasticity is large. 6 · Security 咼 · With triple disaster prevention anomaly protection. 7. Good dimming: according to the actual needs of the market, it can be designed into two types: full-dimming dimming and segment dimming. In addition, the stabilizer has the function of assisting the activation of fluorescent lamps,

! 231350, Description of the invention (3) Warm-up start type 2 · Instant start type; There are several ways to under-actuate • Quick start type. 3, in the current trend of promoting energy conservation and increasing product life, the frequency = liters: the best quality; the second: the higher life, so electronic capacity & extend the life of the lamp officer and the stabilizer itself The owner of the device; ... accepted and loved by users, has gradually become a safety device = electronic device has many of the above advantages, but: the circuit 'is often affected by changes in load, tube 2 girls change, such as: lamp tube rupture, … The characteristic operation of s also follows the danger of fire; the danger of fire in electronic ballasts, even burned out, or fire due to electrical circuits ^ This guide f is the restriction disk used in the above-mentioned customary ballast stabilizer S. Division 3: People then exhausted their minds and devoted themselves to this related research: And, the point of 'improvement' has led to the invention. ^ Exhibition, implementation and [contents of the invention] The technical problem to be solved: the use of f sub-an; ^ disadvantages: the characteristics of = have changed, for example: lamp: current load change, & operation of electronic ballast Risk of fire due to internal cracks, air leaks ... or fire damage. ^ Electronic ballast burner

$ 6 页 1231350 V. Description of the invention (4) The invention is a protection circuit for an electronic ballast, which mainly includes: a protection circuit and an automatic lighting circuit after reset; when an abnormal current state occurs, such as: lamp If the tube is broken, air leaks, etc., it can automatically cut off the oscillation circuit and stop the circuit from oscillating without the danger of high voltage current output. When the damaged or defective lamp is removed and replaced with a good lamp, it can be automatically turned on and used without the need to switch the power on and off. The purpose and effect of technical means: The purpose of the present invention is to provide a protection circuit for electronic ballasts, which can achieve: (1) ensuring that the electronic ballasts are not damaged or burned, (2) no high-voltage current output, which can prevent workers from being damaged Danger of high-voltage electric shock. (3) When the damaged or defective lamp is removed and replaced with a good lamp, it can be automatically lit and used without re-switching the power. [Embodiment] In order to disclose the purpose, features and effects of this creation in detail, the following specific examples are given in conjunction with the accompanying drawings to explain the invention in detail as follows: The protection circuit of the invention is an architecture Operates on the conventional fluorescent lamp ballast circuit and merges with it. Please refer to FIG. 1, which is a circuit diagram of an embodiment of a protection circuit of an electronic ballast of the present invention; the present invention is a protection circuit of an electronic ballast 5 main

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It should include a protection circuit and an automatic lighting circuit after reset; its two protection two circuits are connected to the two electrical two by the output of the electronic ballast circuit: two R8 are grounded; the capacitor cu is connected to the resistor R8-a The anode of the two-pole M D12;-the resistor R9 is connected to the cathode of the diode D12; the other end of the resistor "is grounded through a capacitor ci2; the resistor R9 and the capacitor C12 form a time constant loop; a device R10 is connected in parallel with capacitor HC12; the cathode diode of Dl3 is connected to capacitor C12; R10 is connected to capacitor C12; the anode of DU diode DU is connected to ground via a container C13; the anode of D13 is simultaneously It is also connected to the gate of a SCR gate fluid TH1; the cathode of the SCR gate fluid TH1 is grounded, and the anode is connected to the cathode of a diode D11; the anode of the diode D11 is connected to the primary winding of the electronic ballast drive transformer T 丨One end of A. The automatic lighting circuit after resetting is connected by one end of a resistor R 丨 j to the positive end of the rectified and filtered DC voltage output end of the input power; and then the resistor R12 and the other end of the resistor Rii Series connection, resistor ^ "and . There is a wire connected to one of the filament contacts of the tube; a capacitor ci 4 is connected in series to the other end of the resistor R12, and the other end of the capacitor C14 is grounded;-one end of the resistor R13 is connected to the resistor R12 and the capacitor -C14 connection; a diode D14 whose anode is connected to the other end of the resistor R13; transistor Q3 'its base is connected to the cathode of diode Di4, the emitter of transistor Q3 is grounded and its collector is Then it is connected with the cathode of the diode D1 of the protection circuit and the anode of the SCR brake fluid TH1 to the starting voltage source of the electronic ballast.

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Explanation of the implementation status of the present invention. When the lamp tube is abnormal, for example, because the lamp tube cannot normally point #, & k & rupture, air leakage, etc., the load will be normal in the electronic safety as an electronic ballast. Negative pressure, this abnormal high voltage will cause you to 乂 „i + positive hanging and scratching the electronic ballast circuit will cause the risk of electric shock, and the vulnerable capacitor is described. The protection circuit will abnormally high voltage on the P8 terminal. And;-the pole body D12 'is rectified into a direct current (dc) voltage, / Λ diode D13' when its DC voltage exceeds the zener diode. After the voltage Vz is turned on, the SCR brake fluid will be triggered The TH1 ^ gate turns on T1, and reduces the voltage of the start-up voltage source resistor of the electronic stabilizer to a low potential; the SCR gate fluid T1 is locked to maintain the on-state until the fault is eliminated. In addition, the 'electronic stabilizer' The primary winding T1 A of the driving transformer T1 is connected in series to the filament of the fluorescent lamp, and its two secondary windings τ 丨 B and 1 c are connected to the bases of the transistors Q1 and Q2 in the half-bridge switching circuit. Circuit connection. Under normal circumstances T1B and T1C power The bodies Q1 and Q2 continue to oscillate to form a high-voltage output; and after the aforementioned SCR gate fluid T1 is turned on, T1A will be grounded via diode D11 and then T1 through ground. Based on the foregoing two reasons, the oscillation circuit of the electronic ballast stops being shaken out ' Therefore, it will stop generating abnormal AC high voltage. In addition, the capacitor c 1 2 and resistor R9 in the protection circuit are time constant circuits. Its main function is to determine whether the high voltage coupled through the capacitor C11 is

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V. Explanation of the invention (7) Is it normal? If the DC voltage (DC) rectified by diode D1 2 passes Cl 2 and R9, and the delay time is <1 second, it is considered to be instantaneous when lighting. Voltage pulse, this voltage will not trigger the SCR brake fluid TH1, if its delay is> 2 seconds, then the 'cumulative voltage will pass through the audit diode] due to the integral effect of capacitor c 丨 2 and resistor R 9] 13 The trigger of the SCR gate fluid τΗι makes the SCR gate fluid conductive. In addition, the main function of the capacitor C1 3 is to prevent high-frequency noise interference. The above is the basic operating principle of stopping the ballast to achieve the protection function.

Next 'Describe the automatic lighting circuit after the reset (Reset): Connect the resistor R11 by the DC voltage (DC) rectified and filtered by the input power source' via the resistor R12, capacitor C14, resistor R13, and diode D14 To control the base bias of the transistor Q3 and connect a line a between the resistor R11 and the resistor R12 to the filament P4, the operation steps are as follows:

(1) Under normal lighting conditions, line A forms a low-impedance loop through the filaments p 4, p 3, and then through the primary winding of the drive transformer to til A to ground, and the DC power source through resistor R11 passes through this loop to Grounding, forming a voltage dividing circuit, makes the base voltage of transistor Q3 at a low potential that is not conducting. (2) When the lamp fails, such as: lamp rupture, air leakage, etc., the electronic stability output terminal P8 will generate abnormally high voltage, which will pass through capacitor C11, resistor R8, diodes D12, D13 The gate electrode of the SCR brake fluid TH1 is triggered. After the SCR brake fluid TH1 is actuated, the primary winding resistance T1A of the driving transformer of the oscillation circuit is reduced to a low potential to stop oscillation, and the SCR is asked to flow.

1231350 V. Description of the invention (8) The body TH1 is latched to achieve its protection function. At this time, the transistor Q3 is still in a non-conducting state. (3) When the lamp tube is removed, the DC voltage (dc) is supplied to the transistor through the resistors r η, r 1 2, R13, and diode D14, and the base is biased to make the transistor conductive. Transistor Q3 is connected in parallel with the SCR gate fluid TQ1. The conduction of transistor Q3 will reset the SCR gate fluid TQ1, that is, return to an open state. At the same time, the oscillating circuit is still unable to start without high voltage output. (4) When the lamp is connected, the A line forms a low-impedance loop through the filament terminal P4 and P3, and then through the primary winding of the drive transformer T1 A to ground, and the DC power source through the resistor R11 passes to this ground to ground , To form a voltage divider circuit, so that the base voltage of transistor Q3 is at a low potential that is not conducting, and transistor Q3 is not conducting, which is like an open circuit (0pen circuit), thus making the vibration circuit? The lamp will be turned on automatically after this reset (Reset). The operation of the automatic lighting circuit will return to (丨). '. The capacitor C14 in the automatic lighting circuit after the reset (Reset), its function is: When the lamp is normally lit, the alternating current (AC) voltage of the filament will be bypassed (By pass) to ground through this capacitor C1 4 So that it does not affect the normal operation of transistor q3. It can be seen from the above description that the inconvenience and deficiency of the fluorescent lamp stabilizer in the conventional technology can be improved and overcome by the protection circuit of the electronic ballast of the present invention. Therefore, the performance of the protection circuit of the electronic ballast of the present invention is better than those of the conventional art. The invention does have industrial utilization value and has

Page 11 1231350 V. Description of Invention (9) Novelty and progress, in line with patent requirements. The above is only a preferred embodiment of the present invention, and it is only for the purpose of illustration and is not intended to limit the scope of the present invention and patent application; all other things made without departing from the spirit and scope of the present invention Equivalent changes or modifications should be included in the scope of patent application described below.

Page 12 Example of color protection The device of the road protection and protection The Ding'anzi Ming 1 The issued version is said to be a U-single system ^ Simplified diagram. Figure 1 Figure t. Lu Ming said single abbreviated symbol element [R1 3 resistor capacitor diode R8, R9, RIO, RH, R12 CH, C12, C13, C14 Dll &gt; D12 &gt; D14 D 1 3 Body Q3 transistor TH1 SCR gate fluid A line P3, P4, P7, P8 filament end

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Claims (1)

1231350 6. Scope of patent application: A variety of protection circuits for bun safety, which mainly include a protection circuit and an automatic lighting circuit after reset; of which: ☆ crying protection circuit is connected by the output terminal of the electronic ballast circuit To-electrical pt two% and then to a ground through a resistor R8, the capacitor C 1 1 and the resistor ^ ^ connected to the anode of a diode D12; a resistor 趵, connected to the two: ^ 1 2 cathode; resistance The other end of the resistor R9 is connected to the capacitor via the ground; the resistor 趵 and the capacitor Π2 form a time constant loop H = the resistor R10 is connected in parallel with the capacitor C12; the cathode of the diode is inspected) ^, Λ resistance / R9: Rl0 Connected to capacitor C12; the zener diode and the H valley transformer C1 3 are connected to ground; the anode of the zener diode DJ 3 is also connected to the gate of a SCR gate fluid TH1; the SCR gate fluid TH1 The cathode is connected to 0 ground, and the anode is connected to the cathode of a diode D11; the pole of the diode is connected to the primary winding of the electronic ballast drive transformer T1 A: 玖 保 f: 路 'occurred in the lamp officer In abnormal situations, ㉟ automatically cuts off the oscillation Normal AC high voltage; The automatic lighting circuit after resetting is connected to the positive end of the DC voltage output end of the input power through rectification and filtering by one end of a resistor Ru; then the resistance is R12 and the resistance | §R11 of another— The terminals are connected in series. There is a connection between the resistors ⑴ and ⑴ connected to one of the filament contacts of the lamp, a capacitor. I 4 is connected in series to the other end of the resistor R12, and the other end of the capacitor Π4 is grounded; The-terminal of the resistor R13 is connected to the connection between the resistor R12 and the capacitor ，, a diode D14, whose anode is connected to the other terminal of the resistor R13-the transistor Q3, and its base is connected to the cathode of the diode D14. The emitter of 3 is grounded, and its collector is connected to the cathode of the diode Du of the protection circuit. 1231350 6. The patent application scope of the SCR gate fluid TH1 anode, prostitute source, · Automatic reset after resetting ^ Connect to electronic stability After the start-up voltage of the lamp, 'the lamp can be automatically removed and replaced with a good 2. such as the scope of the patent application item i;'; :: "Re-switch the power supply. In, the capacitor of the protection circuit ⑴ 广 二疋:, Paul: Circuit 'where Λ is described The protection circuit of the sub-ballast, among them, the capacitor C14 of the automatic lighting circuit after resetting is a Bypass grounding function of the AC voltage; when the lamp is normally lit, the AC voltage of the filament will pass The capacitor π4 bypass is grounded so that it does not affect the normal operation of transistor Q3. Page 15