JPH0221593A - Fluorescent lamp lighting-up device - Google Patents

Abstract

PURPOSE:To decrease the dependability of SCR gate operating voltage on temperature by adding the forward voltage of a diode as a gate operating voltage of SCR (a thyristor with one-way gate). CONSTITUTION:When a split voltage Va of a resistor R2, a resistor R3 and a diode D2 increases as a result of an increase in AC power AC until it reaches a gate operating voltage Vg of SCR, SCR is on, and a preheating current Ih flows in such a way that AC power source AC choke transformer CH heating heater h1 SCR anode A SCR cathode K diode D3 preheating heater h2 AC power source, and a fluorescent lamp both-pole heater is preheated. At the same time, a reverse cycle voltage is applied in such a way that AC power source AC diode D1 resistor R1 SCR gate G; this is in a reverse by-pass state. Next, when the preheating current Ih is off, a reaction voltage Vpp of the choke transformer CH is applied to the fluorescent lamp both electrodes, and after several cycle operation, the fluorescent lamp lights up and the voltage between both electrodes drops. Thereby, SCR gate driving voltage Va drops, too, until it becomes lower than the operating voltage Vg, so that SCR is off and the preheating current Ih becomes a breaking state and then, the fluorescent lamp lights up normally.

Description

Detailed Description of the Invention [Technical Field] The present invention relates to a lighting device for a discharge lamp, and more particularly to a starting device using a semiconductor element for a discharge lamp having a preheating electrode. The invention relates to a replay starter with improved temperature characteristics.

``Smart Technology'' Conventionally, glow starters have been mainly used as a starting point for preheating fluorescent lamps, but they take a long time to start in dark places at low temperatures or when the power supply voltage drops. It also has the disadvantage of a short lifespan, resulting in blackening of the fluorescent lamp and shortening its lifespan. In recent years, electronic lighting devices have been developed that overcome the above drawbacks and utilize semiconductor switches. Originally, this type of starting device is used under poor environmental conditions and has a particularly wide temperature range (e.g. -20 to ÷80).
℃) There were restrictions on the parts used due to the circuit configuration. This resulted in high costs and delayed practical application.

The operation will be explained using the example in Figure 1 as a conventional known example.A
C is an AC power supply, FL is a fluorescent lamp with preheating heaters hl and h2, and SCR is a unidirectional gated thyristor (hereinafter S
(referred to as CR), DI, D2 are rectifier diodes, CH
indicates a choke transformer, and R1 to R3 indicate resistors, respectively.

In the waveform shown in the figure, V indicates the power supply voltage, lh indicates the preheating heater tIi current, and Vllll+ indicates the generated pulse voltage. Now exchange'i
When the voltage of source AC rises from point a, resistors R2 and R3
When the divided voltage reaches the SCR gate operating voltage, the SCR turns on at point vb of tR*pressure■, the preheating current rises north from point a, and the AC power supply voltage becomes zero at point 0. However, the current continues to flow with a delay due to the induction effect of the choke transformer, and is turned off at point d during the next reverse cycle. That is, AC power supply AC → choke transformer CH → preheating heater hl-5
CR anode A → SCR cathode → diode F'
The flow is D2 → preheating heater h2 → AC power supply AC, and each bipolar heater of the fluorescent lamp is preheated. At the same time, from point 96 of the reverse cycle of the source to AC, at point e, AC current gAc → diode D
A reverse bias voltage with respect to the gate of SCR is applied to I→resistance R1→gate G of SCR, and reverse bias 'fJR is flowing, but this is blocked by diode D2. Is the heater preheated at point d at this time? I
The SCR is turned off when the E current 1h becomes equal to or less than the holding current of the SCR. Therefore, during the off period (tl), a current flows through the reverse bias, and the heater current is abruptly cut off, and due to the reaction effect of the choke transformer,
A high voltage pulse voltage Vl)Il is generated and applied across the fluorescent lamp. As a result of the above operation, the fluorescent lamp will turn on after several cycles of operation, and the voltage between its two poles will drop, and the voltage will also drop to SCR's G. As a result, the SCR will remain off, and the fluorescent lamp will turn on normally. .

[Object of the Invention] The starting device described above may have a very simple circuit configuration and good starting characteristics, but if considered historically, it has the following drawbacks.

1) As shown in Figure 2, the SCH gate operating voltage is
It is significantly affected by temperature changes, and the switching operation from preheating to normal lighting is not performed properly.

2) Since the gate operating voltage characteristics of the SCR vary widely, it is difficult to determine the operating point constant using the resistors R1 and R2.

[Disclosure of the Invention] The operation of the present invention will be explained below with reference to FIG. 3 without overcoming the drawbacks mentioned above.

Regarding the explanation of the symbols, the explanation given in FIG. 1 above shall be followed.

As the alternating current B source AC rises, the voltage Va divided by the resistor R2, resistor R3, and diode D2 increases, and when it reaches the gate operation applied voltage Vg of the SCR, the SCR turns on and the preheating current 1h changes from the alternating current power source AC→ choke transformer C
) (→ f thermal heater hl → SCR anode A → SCR cathode → diode D3 → preheating heater h2 → AC flows from the source, and the fluorescent lamp bipolar heater is preheated. At the same time, AC Ml source A C → diode DI → resistor R1→SCR
A reverse cycle voltage of G and tR is applied, creating a reverse bias state. Next, when the preheating current 1h is turned off, the reaction voltage Vl)T1 of the choke transformer is applied to both r11 poles of the fluorescent lamp as explained in Figure 1, and after several cycles of operation, the fluorescent lamp turns on. The voltage between the two electrodes decreases.

Therefore, the SCR gate drive voltage Va also decreases, and this voltage becomes lower than the SCR operating voltage ■8, so the SCR is turned off, the preheating IT flow 1h is cut off, and the fluorescent lamp returns to normal lighting. . In the figure, capacitor CI is for malfunction prevention, and C2 is a capacitor for noise prevention and SCR protection.

[Effects of the Invention] According to the above explanation, the advantages that are particularly different from conventionally known examples are as follows.

1) As the 0 operating voltage of ScR, diode D
In other words, the forward voltage of the diode D3 is normally 0 in the case of a silicon type diode.
．． After 7V, the temperature is stable compared to the SCR gate voltage (with respect to temperature), so the SCR operating voltage vg has a considerably improved margin against temperature changes. It is.

2) If we examine it in more detail, diode D3 also has no temperature dependence, and has a so-called negative coefficient in which the forward voltage decreases with a one-point increase in temperature, and this is due to the original gate characteristics of SCR. The same tendency exists, and in order to further correct these, diode D2 was inserted,
By inserting this diode D2, the gate operation detection voltage Va also becomes a direction in which the forward voltage decreases as the temperature rises due to the negative coefficient of the temperature of the diode FD2, and can be ignored by the diodes 1'D2 and D3.

As a result, the operating voltage of the SCR is determined only by the relationship between the forward voltage of the diode D3 and the gate voltage of the SCR. In particular, the gate sensitivity of small SCRs is high, e.g. 0.3 to 0.4v.
As the temperature rises, the sensitivity decreases and the sensitivity increases. On the other hand, the influence of the SCR of 0.3 to 0.4 square meters on the voltage in the 1llfi direction of the diode D3 is considerably improved, and the operating margin is increased. The resistor R2 in the figure is mainly used to determine the preheating flow and, at the same time, to determine the switching voltage for preheating and lighting. The resistor R1 is a resistor that determines the gate reverse bias state flow of the SCR and adjusts the high voltage pulse generation voltage. That is, when the bias current is large, the off time of the preheating current is shortened and the generated voltage is high, and in the opposite case, the generated voltage is low. At the same time, the gate reverse bias current is blocked in the IF force direction by the diodes 1''D2 and D3, and the losses in R1 and R3 are particularly small.

Further, the reverse bias resistor R1 has a synergistic effect that works to suppress the SCR sensitivity at high temperatures. As described above, the present invention provides a practical starting device that exhibits excellent stability even under a wide range of operating temperatures and has a simple circuit system.

[Brief explanation of the drawing]

Figure 1 shows a known example of a conventional circuit and its operating waveform diagram. Figure 2 is a characteristic example showing the influence of operating temperature on SCR gate operating voltage. FIG. 3 is a diagram showing an example of the circuit of the present invention.

Claims (1)

[Claims] In a circuit consisting of a stabilizing choke transformer and a fluorescent lamp having a preheating electrode connected in series with an AC power source, a gated unidirectional thyristor and a diode are connected between the preheating electrode on the non-power side of the fluorescent lamp. A resistor for detecting the voltage between the preheating electrodes and another resistor are connected in series, and a diode is connected in series, and a reverse bias resistor is interposed between the gate of the thyristor from each resistor connection point, A fluorescent lamp lighting device characterized in that another diode is connected to the connection point in a polar direction such that a reverse bias negative current is supplied from an AC power source to a gate of a thyristor.