WO2002082865A1

WO2002082865A1 - Starter for an non-flash fluorescent lamp

Info

Publication number: WO2002082865A1
Application number: PCT/EP2002/003167
Authority: WO
Inventors: Foo Onn Fah
Original assignee: Mass Technology (H.K.) Ltd.; Wiesner, Werner, Th.
Priority date: 2001-03-29
Filing date: 2002-03-21
Publication date: 2002-10-17
Also published as: CN1378411A

Abstract

A starter for a non-flash fluorescent lamp comprises a starter bulb (2), at least one resistor-type sensing element (3), said resistor-type sensing element (3) is a composite thermistor (3) bonded together by a varistor (31) and a thermistor (32), said composite thermistor (3) is connected to said starter bulb (2), in parallel. Because the starter of this invention employs a composite thermistor (3) or other resistor-type sensing elements, the cathode in the fluorescent lamp has an electronic emitting capability strong enough to generate a high voltage pulse and start discharging, so the fluorescent lamp can reach a steady lighting point with no flash. The starter according to this invention is reasonable in structure, reliable and stable in performance, and less expensive in cost, and it can extend the life time of the lamp tube considerably.

Description

STARTER FOR A NON-FLASH FLUORESCENT LAMP

This invention relates to a starter for a fluorescent lamp, especially to a starter for a non- flash fluorescent lamp with no flash during starting.

The starter for an induction ballast-type fluorescent lamp now available on the market is composed of a starter bulb 1 and a capacitor Cl, wherein the capacitor Cl serves to protect from interference. Starter bulb 1 is a lighting fluorescent lamp, as shown in Fig 6. When the power of the fluorescent lamp is connected, the starter bulb 1 will immediately glow discharge, its moving plate will close after being heated, and will hop away in a short time after cooling, and generates a transient induction high voltage, making the fluorescent lamp breakdown for lighting. However, because the closing time of the moving plate is usually shorter than the preheating time required by the tube of the fluorescent lamp, the cathode of the tube has not reached the temperature high enough to have emitting capability. At this time, the working voltage of the light tube is higher than the voltage supplied normally, so after the transient induction high voltage on the starter bulb 1, the lamp tube will go out. After the tube is extincted, the starter bulb 1 will glow discharge again, repeating the above process. After many times of circulation, i.e., after many times of flashes, the tube cathode reaches a temperature high enough, the working voltage of the lamp tube is lower than the supply voltage, at this time, the lamp tube enters a normal lighting state. Apparently, such flash makes one uncomfortable on the one hand, and on the other hand, damages the lamp tube and shortens the life of the tube.

In order to solve the problem of repeated flash for the conventional starters, an electronic starter is once proposed. Such starter is composed of a plurality of electronic modules and complex electronic circuits, and the starting cathode of the fluorescent lamp has sufficient electronic emitting capability to reach the normal lighting point of the lamp and can overcome the drawbacks of its repeated flash. However, such electronic starter is very expensive, about 10 times the price than an ordinary starter, so it is very hard to be popularized, hi addition, such electronic starter has a low reliability due to its complicated structure.

The object of this invention is to overcome the above defects and provide a starter for a non-flash fluorescent lamp, which allows the fluorescent lamp supplied by an induction ballast to preheat and start reliably with no flash.

The technical solution for achieving the above object is: a starter for a non-flash fluorescent lamp according to one aspect of this invention comprises a starter bulb and at least one resistor-type sensing module or element, said resistor-type sensing module or element is a thermistor connected to said starter bulb in parallel.

According to another aspect of this invention, the technical solution for achieving the above mentioned object is a starter for a non-flash fluorescent lamp comprising a starter bulb and at least one resistor-type sensing element, said resistor-type sensing element is a varistor connected to said starter bulb in parallel.

With the simple low-cost starter circuit according to the invention it is possible to prevent flashes when fluorescent lamps are switched on to an alternating-current supply voltage having a frequency of 50 Hz or 60 Hz.

In the starter for a non-flash fluorescent lamp according to the present invention, the cold resistance value of said thermistor is in the range of 50 - 1500 ohms.

In the starter for a non-flash fluorescent lamp according to this invention, the breakdown voltage value of said varistor is in the range of 40 - 400 N.

In the starter for a non-flash fluorescent lamp according to the present invention said resistor-type sensing element is a composite thermistor bonded together by a varistor and a thermistor, this thermistor of said composite thermistor is connected in series to said varistor, said composite thermistor is connected to said starter bulb in parallel.

Since the starter according to this mvention employs a composite thermistor or a resistor-type sensing module composed of thermistor and varistor, the cathode and electrode, respectively, for the fluorescent lamp has an electronic emitting capability strong enough to generate a high voltage pulse and glow discharge, so that the fluorescent lamp can reach steady lighting point under flash-free condition; and the starter according to this invention is reasonable in structure, reliable and steady in performance, low in cost and can extend the lift time of the lamp tube considerably.

In order to comprehend the object, features and advantages of this invention, a specific explanation to the preferred embodiments of this mvention will be made as follows in conjunction with the drawings, in which:

Fig. 1 is a circuit diagram of the starter according to the first embodiment of this invention;

Fig. 2 is a circuit diagram of the starter according to the second embodiment of this invention;

Fig. 3 is a circuit diagram of the starter according to the third embodiment of this invention;

Fig. 4 is a circuit diagram of the starter according to the fourth embodiment of this invention;

Fig. 5 is a voltage waveform diagram measured on both ends of the lamp tube when the starter of Fig. 1 is used in a 36W,T8 fluorescent lamp;

Fig. 6 is a diagram of a circuit principle for the starter of prior art;

Fig. 7 is a voltage waveform diagram measured on both ends of the lamp tube when the starter of Fig. 6 is used in a 36W,T8 fluorescent lamp. Please refer to Fig. 1, which shows the starter circuit for the non-flash fluorescent lamp in the first embodiment of this invention, the starter comprises a starter bulb 2 and a resistor-type sensing module, said resistor-type sensing module is a composite thermistor 3 which comprises a thermistor 32 which is bonded together by a varistor 31 with a certain breakdown voltage. The composite thermistor 3 is connected to starter bulb 2 in parallel, the breakdown voltage value of said metal oxide varistor 31 can be selected in the range of 40 - 400 N. The varistor 31 preferably is a zinc oxide varistor, the fundamental characteristic of which is that the resistance value decreases rapidly with the increase of the voltage exerted on the varistor. When the external voltage is low, the resistance value is very high and the current is very low; when the external exerted voltage reaches and surpasses a certain critical value (this critical voltage is also called pressure-sensitive voltage, working voltage or breakdown voltage), the resistance value decreases rapidly and the current increases rapidly. For instance in Fig. 1, Zinc Oxide Varistor 31 is a Chinese product, the type of which is ZH 07D150K.

The cold resistance value of said PTC (Positive Temperature Coefficient) thermistor 32 is in the range of 50 — 1500 ohms. The feature of a composite thermistor 3 is consistent with that of a thermistor, i.e., when voltage applied thereon exceeds the breakdown voltage of varistor 31, current flows through thermistor 32, and the heat produced by the current flowing through the varistor 31 will be immediately transferred to the thermistor 32 to make its resistance value rising rapidly and so the temperature of thermistor 32 rises. Along with the rising temperature, the resistance value of thermistor 32 will also rise rapidly. Application of composite thermistor 3, in addition to allow the temperature of thermistor 32 to rise rapidly, makes the temperature of varistor 31 rise slower, thus improving the sensibility of the thermistor and the reliability of the varistor 31.

The above starter circuit is connected to the two filaments A, B or two pins of the lamp tube for the fluorescent lamp supplied by the induction ballast for stabilization. When the power of the fluorescent lamp is connected, starter bulb 2 will glow discharge, the moving plate closes and hops away, generating a transient induction high voltage. The composite thermistor 3 connected to starter bulb 2 in parallel can control the magnitude of the high voltage. For different tube types, power and supply voltage, suitable electric parameters for the composite thermistor 3 are selected, so that its voltage value does not reach the breakdown voltage of the lamp tube and thus the tube will not breakdown for lighting, i.e., it will not flash. Through times of circulation, on the one hand, the tube electrode and cathode, respectively, is sufficiently preheated, on the other hand, the resistance value of the composite thermistor 3 will rapidly rise due to heating, making the induction voltage applied on the lamp tube rise, at this time the tube breaks down and enters normal lighting point and thus realizing a start for the fluorescent lamp with no flash. After starting, the voltage drop of the tube is low, usually lower than the breakdown voltage of varistor 31. Thus, there is no current flowing through and no power is consumed. Besides, because varistor 31 has a capacitance of several hundred pF, it serves to eliminate interference, and it is not necessary to connect a capacitor for eliminating interference as practiced in the prior art.

Please refer to Fig. 1 and 5, which show a voltage waveform measured at both ends A, B of the lamp tube when the power to the fluorescent lamp is connected, and said composite thermistor 3 is used in the working circuit of a 36W, T8 fluorescent lamp.

A storage oscilloscope is used for measurement. This voltage wave shape is an envelope wave shape. The frequency of the power supply of the fluorescent lamp is 50 cycles or 60 cycles, i.e., there are 50 cycles or 60 cycles within one second. In the oscillo- gram, on account of being too dense, there is only a stretch of black color. But the voltage peak value (i.e., the envelope point) of the wave shape and its changing with time, i.e., the envelope wave shape can be shown. In the oscillogram one narrow line can possibly include the wave shape of several cycles. From Fig. 5, it can be seen that when the time is about one second and the circuit is switched on, the wave shape appears. At this time, the voltage of the peak value is about 255 N. With the time increasing, this voltage of the peak value is also increasing. This is because the current passing through the two elements 31 and 32 creates heat, making the resistance value of 32 increase and the voltage peak value also increases. When the time is about 2.2 seconds, the rotor plate of jumping bulb 2 becomes short-circuited owing to being heated. In consequence, at this time, the voltage becomes zero. After about 0.4 seconds, one narrow wave shape appears in a very short time, which is created because the rotor plate in the jumping bulb 2 jumps away due to the cooling after being short-circuited. But because when the rotor plate jumps away, the distance between the rotor plate and the stator plate is very short making the glow between the rotor plate and stator plate heat again and quickly closing and being short-circuited occurs again. The amplitude value of the wave shape is determined by the value of the pressure-sensitive voltage of varistor 31 in the composite thermistor and the voltage of thermistor 32. Afterwards, the several wave shapes which appear, go through the same process as the above. When the time is 3.7 seconds, the final narrow wave shape appears. Because the cathode and electrode, respectively, has already had sufficient temperature, the tube discharges electricity coming into the normal ignition. The peak value of the tube voltage drop is lower than 200 N. At this time, the jumping bulb produces no glow. Therefore, from Fig. 5, we can see four induction high voltage pulses, their magnitude is only about 400 N due to the control of composite thermistor 3. Along with the passing of time, the current preheats the two cathodes of the lamp tube, making the breakdown voltage of the tube drop, the lamp tube does not breakdown until the third pulse, so there is no flash, and the tube breaks down and enters a normal lighting point in the fourth pulse.

Please refer to Fig. 6 and 7, which as a comparison show a voltage waveform measured at both ends A, B of the lamp tube LA when the power of the fluorescent lamp is connected, and a starter with capacitor Cl of the prior art is used in the working circuit of the same 36W, T8 fluorescent lamp. From Fig. 7, we can see four induction high voltage pulses, their magnitude is over 700 N. Such voltage is high enough to breakdown the lamp tube of cold cathode, thus generating flash. In Fig. 7 , first three high voltage pulses show three flashes, after the fourth high positive pulse, the lamp tube enters into a lighting point of steady discharge.

Please refer to Fig. 2, which is a circuit diagram for the starter in the second embodiment of this invention. Said resistor-type sensing element is a thermistor 4 and a varistor 5, said thermistor 4 and varistor 5 are serially connected and then connected to starter bulb 2 in parallel. The resistor-type sensing module of this starter can be considered as a composite thermistor in Fig. 1 substituted by a series varistor 5 and a thermis- tor 4, which can also meet the requirement of no flash, but the varistor 5 requires higher shock-proof capability.

Please refer to Fig. 3, which is a circuit diagram for the starter in the third embodiment of this invention. Said resistor-type sensing element is only a varistor 6, said varistor 6 is connected to starter bulb 2 in parallel, which can also meet the requirement of no flash, but the scope of adaptability of the starter to the tube is limited.

Please refer to Fig. 4, which is a circuit diagram for the starter in the fourth embodiment of this invention. Said resistor-type sensing element is only a thermistor 7, said thermistor 7 is connected to starter bulb 2 in parallel, but the thermistor will consume power when at normal working.

In the second through to fourth embodiment, the breakdown voltage value of the varistor can be in the range of 40 - 400 N, and the cold resistance value of said thermistor is in the range of 50 - 1500 ohms.

Claims

1. A starter for a non-flash fluorescent lamp comprising a starter bulb, further comprising at least one resistor-type sensing element, characterized in that said resistor-type sensing element is a thermistor (7) connected to said starter bulb

(2) in parallel.

2. The starter for a non-flash fluorescent lamp according to claim 1, characterized in that the cold resistance value of said thermistor (7) is in the range of 50 - 1500 ohms.

3. A starter for a non-flash fluorescent lamp comprising a starter bulb, further comprising at least one resistor-type sensing element, characterized in that said resistor-type sensing element is a varistor (6), said varistor (6) is connected to starter bulb (2) in parallel.

4. The starter for a non-flash fluorescent lamp according to claim 3, characterized in that the breakdown voltage value of said varistor (6) is in the range of 40 - 400 N.

5. The starter for a non-flash fluorescent lamp according to any of claims 1 to 4, characterized in that said resistor-type sensing element is a thermistor (4) and a varistor (5), said thermistor (4) and varistor (5) are series connected and then connected to starter bulb (2) in parallel.

6. The starter for a non-flash fluorescent lamp according to any of claims 1 to 5, characterized in that said resistor-type sensing element is a composite thermistor (3) bonded together by a varistor (31) and a thermistor (32), said thermistor (32) in series connection to varistor (31) of said composite thermistor (3) is connected to said starter bulb (2) in parallel.

7. The starter of a non-flash fluorescent lamp according to claim 6, characterized in that the cold resistance value of said thermistors (4, 32) is in the range of 50 - 1500 ohms, the breakdown voltage value of said varistors (5, 31) is in the range of 40 - 400 N.

8. The starter for a non-flash fluorescent lamp according to any of claims 1 to 7, characterized in that said starter bulb (2) and said fluorescent lamp are connected to an alternating- current supply voltage of 50 Hz or 60 Hz.

9. The starter for a non-flash fluorescent lamp according to any of claims 1 to 8, characterized in that the resistor-type sensing element is selected such that its voltage drop does not reach the breakdown voltage of the lamp tube of the fluorescent lamp.