JPS6240195A - Discharge lamp starter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field] The present invention starts a discharge lamp when using a fluorescent lamp! ! It's about location.

[Background Art] Figure 3 shows a conventional circuit. ! ! Both filament electrodes 5 and 6 of a discharge lamp 4 such as a fluorescent lamp are connected to a power source 1 via a power switch 2 and a ballast 3, and a terminal a corresponding to the non-power side ends of both filament electrodes 5 and 6 is connected to the power source 1 through a power switch 2 and a ballast 3. , b, a series circuit consisting of a diode 7 and a thermal switch 1o, which is always in M configuration and is made of two opposing bimetals 8 and 9, is connected between them.

A series circuit of a constant voltage diode 11 and a first heater 12 is connected between both ends of the diode 7 so that the 7 node side of the diode 7 and the 77 node of the constant voltage diode 11 match, and the constant voltage ril :J' l +
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Connect a series circuit of diode 13 and resistor 14 to Q,
A series circuit of a resistor 15, a constant voltage diode 16, and a second heater 17 is connected in parallel with the resistor 14. terminals a, b
A capacitor 19 connected between them is for noise prevention.

The first heater 12 is thermally connected to the main bimetal 8 of the thermal switch 10, and the second heater 17 is thermally connected to the auxiliary bimetal 9.

In this conventional circuit, when the power switch 2 is turned on, the commercial power supply 1 is connected to the power switch 2, the filament electrode 5 on one side of the discharge lamp 4, the terminal a1 diode 7, the normally closed thermal switch 10, and the terminal.

In the circuit of the other filament electrode 6 and the ballast 3, a half-wave preheating current flows in the positive half cycle by the diode 7 from time t0 to t2 in FIG. 4(a).

Here, the preheating current shown in FIG. 4(, ) is the same as that of the ballast 3 even if the voltage waveform of the commercial power supply 1 shown in FIG. 4(d) passes the zero point at time t and enters the negative half cycle. Due to the action of inductance, the flow continues until time t2, and becomes zero at time t2.
Hereafter, the commercial power supply 1, the ballast 3, the other filament electrode 6 of the discharge lamp 4, the terminal b, the thermal switch 10, the first heater 12, the constant voltage diode 11, the one filament electrode 5 of the terminal a1, the power switch 2 Current flows in a circuit. This current is small because the first heater 12 has a relatively high resistance, and the heater 12 generates heat due to this current. For this reason, the main bimetal 8 is heated and begins to curve, and at time t after time Tr has elapsed since the power switch 2 was turned on,
The contact 18 of the thermal switch 10 opens as shown in FIG. 4(c), and at this time, due to the action of the inductance of the ballast 2, a kick pulse Vp is generated as shown in FIG. 4(b).
is applied between both filament electrodes 5 and 6 of the discharge lamp 4, the discharge lamp 4 is started and lit, and the voltage across the discharge lamp 4 then has a lighting waveform as shown in the figure. After lighting, the input current waveform shown in FIG. 4(a) becomes a two-wave lamp current waveform.

Now, while the discharge lamp 4 is on, the voltage across the terminals a and b of the dark discharge lamp 4 causes the circuit of the diode 7, first heater 12, diode 13, resistor 14, and terminal A small current flows and the heater 12 continues to heat up, so that the thermal switch 10 continues to keep the contact 18 open and the discharge lamp 4 to remain lit.

, while the voltage between terminals a and b during the α lamp is low to some extent, the resistance is 1.
5. Almost no current flows through the circuits of the constant voltage diode 16 and the second heater 17.

Ideally, the Zener voltage of the voltage regulator diode 16 should be set to a value greater than the maximum value of the variations in tube voltage (variations in the ballast 3, discharge lamp 4, power supply voltage, ambient temperature, etc.), so that It is good that the heater 17 is no longer heated, but since the heating power of the heater 17 cannot be obtained in the event of startup failure or restart, which will be described later, the Zener voltage of the constant voltage diode 16 should be set low so that the heater current flows even when the heater is turned on. It is.

Now, due to fluctuations in the power supply voltage, fluctuations in the temperature around the discharge lamp, etc., the tube voltage between terminals a and b has fluctuated considerably.The voltage between the terminals of the heater 12 is now almost constant, and the electric power of the heater 12 is also constant, and the thermal switch 1o It is possible to stabilize the open state of .

If the kick pulse V generated at time t4 in FIG.
When the discharge lamp 4 fails to start due to a low p value or when restarting (when the power is turned off and turned on again after α lamp), the thermal switch 1o becomes open and the discharge lamp 4
Since no lamp current flows through terminals a and b, the voltage across terminals a and b increases almost to the power supply voltage. Current also flows through the terminal circuit, and the amount of heat generated by the first heater 12 increases the amount of heat generated by the second heater 1.
By setting the calorific value of 7 sufficiently large, the degree of curvature of the auxiliary bimetal 9 is greater than that of the main bimetal 8, and the contact 18, which is once opened, closes again after a short period of time, returning to the initial state. After preheating, the engine can be opened and restarted by generating the kick pulse Vp.

This figure shows the power for keeping the heaters 12 and 17 open, and when the tube voltage of the heater 12 exceeds a certain value due to the action of the constant voltage diode 11, the heater power becomes constant. Furthermore, when the tube voltage of the heater 17 is higher than the Zener voltage of the constant voltage diode 16, the heater 17 starts to heat up and its power increases as the tube voltage rises.

The holding performance of the contact 18 of the thermal switch 10 is determined by the heater 1.
2 and the heater 17 (this is called the holding power), and has a chevron-shaped waveform.

In other words, the power of the heaters 12 and 17 is adjusted so that whether the tube voltage is high or low, the power to maintain it decreases and is maintained within the variation range of the tube voltage.

By the way, the fluctuation of the tube voltage is quite large (also, it is difficult to set the circuit constants in the circuit shown in Figure 5, and there is little margin.
For 0W, tube voltage 41V to 75V For 30W, tube voltage 3
It has the disadvantage that it is difficult to share circuit constants because it varies greatly depending on the usage conditions such as the ambient temperature of the discharge lamp, such as 5V to 65V.

Furthermore, in order to increase the holding power, it is easy to increase the power of the heater 12 and reduce the power of the heater 17, but this would result in a large temperature rise, making it impossible to downsize the device, and worsening the restart performance. Because of this problem, the difference between the heaters 12 and 17 cannot be increased too much.

Also, as shown in FIG. 6, the terminal a is connected to the comparator 21.

The voltage between terminals a and b is compared with the reference voltage, and when the voltage between terminals a and b is low, the output of the comparator 21 turns off the transistor 23 inserted in series with the heater circuit 22, and the voltage drop across the transistor 23 is reduced. A resistor 24 is connected in series to the heater circuit 22 to lower the voltage of the heater circuit 22, and conversely, when the voltage between terminals a and b is low, the transistor 23 is turned on to increase the voltage of the heater circuit 22.
The inventors devised an improvement measure in which the voltage of the heater circuit 22 was made to respond to the tube voltage, but in the case of this circuit, it was found that sufficient power could not be supplied to the heater circuit 22 at the time of restarting, etc. There was a problem.

[Object of the Invention] The present invention has been made in view of the above-mentioned problems, and its purpose is to improve the ability of a thermal switch to maintain its open state against fluctuations in tube voltage of a discharge lamp due to ambient temperature. There is a mini discharge lamp starting device that can keep the lamp stable and has good restart performance.

[Disclosure of the invention 1 The present invention will be explained below with reference to Examples.

Figure 1 shows the configuration of this embodiment. In this embodiment, at the point where the temperature-dependent element 20 consisting of 1±negative characteristic thermistor is inserted between the auxiliary bimetal and the second heater 17, fjI
This is similar to the conventional example shown in Figure J3.

This temperature-dependent element 20 has a high impedance when the ambient temperature is low, and a low impedance when the ambient temperature is high.
Installed near the Therefore, when the ambient temperature is low, the tube voltage of the discharge lamp 4 after lighting is high, and the voltage between terminals a and b is low.

However, the temperature-dependent element 20
1IP-person-1-manヱ〜Rehe 朋朋 肿气发收减小，电池17的电力减小。 1IP-person-1-manヱ〜Rehe 朋朋 肬击收减小，电池电力减小。 1IP-person-1-manヱ〜Rehe 朋朋 肬卡收动减小，电池17的电力减小。 1IP-人-1-人ヱ〜Rehe 朋朋 肬卡沉淀，电池17的电力减小。 1IP-人-1-人ヱ〜Rehe 朋朋 肬卡沉淀，电池17的电压减小。 The heater 12 is supplied with constant power by the constant voltage diode 11. Therefore, even when the tube voltage is high, the holding power of the thermal switch 10 is increased.

Conversely, when the ambient temperature is high, the tube voltage becomes low, but the impedance of the temperature-dependent element 20 also becomes small, so the terminal a
The voltage between points A and C does not become much lower than the voltage between terminals a and b. Therefore, the change in the holding power of the thermal switch 10 is also small.

As described above, even if the tube voltage of the discharge lamp 4 varies due to surrounding conditions, the variation width between terminals a and C can be made smaller than the variation width of the voltage between terminals a and b (corresponding to the voltage between terminals a and b). Retention performance is improved.

Further, since this allows for a margin in design, the main circuit can be shared even for different types of discharge lamps 4. Furthermore, in the event of restart or startup failure, the voltage between terminals a and b (power supply voltage) will be higher (power supply voltage) than when the light is on, even when the temperature is low and the impedance of the temperature-dependent element 20 is large (power supply voltage), so the temperature dependence The current flowing through the element 20 causes self-heating and the resistance value drops rapidly, and sufficient power is supplied to the heater 17, which closes the thermal switch 10 and starts the operation.

FIG. 2 shows an example of "Daijō JL Physician". This embodiment is different from the conventional example shown in FIG. 3 in that a temperature-dependent element 20 such as a negative characteristic thermistor is inserted in the same position instead of the resistor 15.
Temperature dependent element 20 functions similarly to the circuit of FIG.

That is, when the ambient temperature is low (the tube voltage is high), the impedance becomes high and the power of the heater 17 is reduced, and when the ambient temperature is high (the tube voltage is low), the impedance becomes low.
Since the current is limited by the constant voltage diode 16 and is hardly affected, there is no change in the holding power of the thermal switch 10. At this time, the heater 12 is connected to the constant voltage diode 1
1, the power is constant at both low and high temperatures.6 Therefore, the retention performance is improved especially at low temperatures. Also, when restarting,
The operation when starting fails is also the same as that shown in FIG.

[Effects of the Invention] As described above, in the present invention, since the power supply to the heater is controlled using a temperature-dependent element, the normally closed contact of the thermal switch can be maintained even when the tube voltage varies depending on the ambient temperature condition. It has the advantage of being able to maintain stable performance, and because only temperature-dependent elements are used, circuit design is easy, and it is possible to easily accommodate differences in discharge lamp types.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of Embodiment 1/') of the present invention, Fig. 2 is a circuit diagram of Embodiment 2 of the present invention, Fig. 3 is a circuit diagram of a conventional example, and Fig. 4 is a circuit diagram of Embodiment 2 of the present invention.
The figure is a waveform diagram for explaining the operation of the same as above, Figure 5 is a diagram for explaining the operation of the same as above, and Figure 6 is a circuit diagram of another conventional example. Electrodes, 8 and 9 are bimetals, 10 is a thermal switch, 12 is a first heater, 17 is a second heater, 18 is a normally closed contact, and 2o is a temperature-dependent element. Agent Patent Attorney Ishi 1) Ai 7Figure 1Figure 3Figure 4Figure 5Figure 6

Claims (1)

[Claims] (1) Connect a commercial power supply to the power supply side terminals of both filament electrodes of the discharge lamp via a ballast, and connect the normally closed contacts of a thermal switch using a pair of bimetals to the non-power supply side terminals of both filament electrodes. At startup, a preheating current is passed through the filament electrode via the thermal switch, and a current is also passed through the first heater that heats and drives the thermal switch.When the preheating current passes for a certain period of time and the normally closed contact of the thermal switch opens. It is equipped with an energizing circuit that applies a constant voltage using the tube voltage of the discharge lamp as a power source to the heater, and energizes a second heater that heats the thermal switch when the tube voltage exceeds a certain level. In a discharge lamp starting device that maintains an open state, a temperature-dependent element that detects the ambient temperature of a device such as a discharge lamp and changes impedance according to the detected temperature is connected to a second heater when the detected temperature is low. A discharge lamp starting device characterized in that the device is inserted into the energizing circuit so as to limit the power supplied to the discharge lamp.