JPH0145200B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a thermally responsive switch type discharge lamp lighting device using bimetal.

[Background technology]

FIG. 1 shows one of the conventional examples. In FIG. 1a, F is a discharge lamp, which is connected to an AC power source E via a ballast L. Further, 1 and 2 are bimetallic, and as shown in FIG. 1b, heaters H ₁ and H ₂
It is designed to be heated by Bimetals 1 and 2 are metal plates 1a and 2a with low coefficient of thermal expansion.
and metal plates 1b and 2b having high coefficients of thermal expansion are bonded together, and when the heaters H ₁ and H ₂ are heated, they curve in the directions shown by arrows P and Q, respectively. However, in the conventional example, the contacts made of bimetals 1 and 2 are normally closed, and when the power is turned on for lighting, a preheating current flows from diode D ₁ through bimetals 1 and 2, and when the phase is opposite, bimetal 2 , 1 and heater H ₁
Current flows through the heater _H1 , which generates heat and heats the bimetal 1. The bimetal 1 is bent in the opening direction, and the contacts are opened after a certain period of time, and at that time, the pulse voltage generated by the ballast L lights up the discharge lamp F. After lighting, current flows through the resistor R to the heater _H1 , keeping the contacts open. In addition, if the lamp does not light up, or if you temporarily turn off the power and immediately turn it on again, the lighting determination circuit 3 determines whether the lamp is lit depending on whether the voltage across the lamp is the power supply voltage or the lamp voltage. H ₂ is turned on, heating the bimetal 2 and forcibly closing the contact. However, such conventional examples have the following drawbacks.

The amount of heat generated by the heater _H1 during lighting fluctuates greatly due to fluctuations in the lamp voltage due to power supply voltage, ambient temperature, etc., and if the interval between the contacts is set to an appropriate size when the lamp voltage is low, the contacts will open when the lamp voltage is high. If the interval becomes too large, it will take a very long time for the contacts to turn on again when restarting, and if the interval between the contacts is set to an appropriate size when the lamp voltage is high, conversely, the contacts will not close when the lamp voltage is low. It has the disadvantage that it cannot be kept open.

When turning off the power and immediately turning on the lamp from a lit state, power supply voltage is applied to both ends of the starter, and the amount of heat generated by the heater _H1 will be several times greater than when the lamp is lit. Therefore, the bimetal 1 is curved in a direction that further increases the distance between the contacts, and in order to forcibly open the contact within a short period of time, it is necessary to increase the amount of heat generated by the heater _H2 .

[Purpose of the invention]

The present invention has been made in view of the above-mentioned points, and by keeping the heater power constant to keep the bimetallic contacts open during lighting, fluctuations in the contact spacing due to fluctuations in lamp voltage, etc. can be suppressed. It is an object of the present invention to provide a discharge lamp lighting device that prevents this problem and always maintains an appropriate contact interval.

[Disclosure of the invention]

The structure of the present invention will be explained below with reference to the illustrated embodiment. As shown in FIG. 2, a pair of filament
a discharge lamp F having filaments f ₁ and f ₂ , an inductive ballast L interposed in series between the power supply side ends of the filaments f ₁ and f ₂ of the discharge lamp F and an AC power supply E; A contact point S consisting of a bimetal 1 and a second bimetal 2
and a diode inserted in series between the non-power supply side ends of the flyments f ₁ and f ₂ of the discharge lamp F and the contact S.
_D1 , a first heater H1 whose one end is connected to the connection point between the diode _D1 and the contact S, and which heats the first bimetal ₁ and opens the contact S when energized;
A resistor R connects the first heater H ₁ across the contact S, and a resistor R connects the first heater H ₁ across the series circuit of the diode D ₁ and the first heater H ₁ . A constant voltage diode ZD that stabilizes the voltage applied to H ₁ , a lighting determination circuit 3 that determines whether or not the discharge lamp F is lit, and an output of the lighting determination circuit 3 that energizes when the discharge lamp F is not lit. is,
When energized, the second bimetal 2 is heated and the contact S
and a second heater _H2 that closes the circuit. FIGS. 3 to 5 are circuit diagrams for explaining operations at the time of starting, lighting, and restarting, respectively, in this embodiment. First, when the power is turned on at startup, as shown in Figure 3, the diode
A preheating current I ₁ flows through D ₁ and bimetals 1 and 2. When the phase is opposite, current _I2 flows through bimetal 2,1, heater _H1 , and constant voltage diode ZD, heater _H1 generates heat, and heats bimetal 1.
After a certain period of time, the contact S is opened, and the pulse voltage generated by the ballast L lights up the discharge lamp F. Next, during lighting, as shown in Figure 4, the diode
A constant voltage diode ZD is connected in parallel to D ₁ and heater H ₁ in series, and current I ₃ flows so that a constant voltage is maintained between a and b regardless of the magnitude of the voltage across the lamp. Regardless of the voltage across the lamp, the heater _H1 generates a certain amount of heat and keeps the contact S open. Furthermore, when the power is temporarily turned off while the lamp is lit and then turned on again, the lighting discrimination circuit 3 is turned on because the voltage across the lamp is the power supply voltage, as shown in Fig. 5, current I ₄ flows, and heater H ₂ generates heat. The bimetal 2 is heated to forcibly close the contact S.
At this time, a constant voltage is applied to the heater _H1 by the constant voltage diode ZD, and the electric power (heat amount) does not increase from the holding state, so that the bimetal 1 does not bend further.

In the embodiment shown in FIG. 6, a constant voltage diode ZD ₁ is used as the lighting discrimination circuit 3. In this embodiment, when the discharge lamp F is turned on and the voltage across the discharge lamp F decreases, the constant voltage diode ZD ₁ is turned off and the heater H ₂ is not heated. Further, when the discharge lamp F is not lit and the voltage across the discharge lamp F is approximately equal to the power supply voltage, the constant voltage diode ZD ₁ is turned on and the heater H ₂ is heated. Next, in the embodiment shown in FIG. 7, the base current of the transistor Tr ₁ is controlled by a series circuit of a constant voltage diode ZD ₁ and a resistor R ₁ , and when the discharge lamp F is not lit, the transistor Tr ₁ is controlled. Heater H ₂ turned on
is heated. Furthermore, in the embodiment of FIG. 8, the current flowing through the heater _H2 is turned off and on by turning on and off the transistor _Tr2 connected in parallel to the heater _H2 . When the discharge lamp F is not lit, the constant voltage diode ZD ₁ is turned on and the transistor Tr ₁ is turned on, so the transistor Tr ₂ is turned off and current flows to the heater H ₂ . At this time, the upper limit value of the voltage applied to the heater _H2 is limited by the constant voltage diode _ZD2 . Also discharge lamp F
When lit, the constant voltage diode ZD ₁ is turned off, the transistor Tr ₁ is turned off, the transistor Tr ₂ is turned on, and the current flowing to the heater H ₂ is turned off.

Next, in the embodiment shown in FIG. 9, a thermistor NTC is built into the base circuit of the transistor Tr ₁ , and the thermistor NTC is heated by the resistor R ₂ that generates heat at the time of restart.
An emission protection circuit is provided which turns off the transistor _Tr1 by changing the resistance of the thermistor NTC when the discharge lamp F is restarted for a long time during emission emission. Further, in the embodiment shown in FIG. 10, an Emiles protection circuit is constructed using a CR timer circuit consisting of resistors R ₃ and R ₄ , a capacitor C ₁ , a constant voltage diode ZD ₃ , and a transistor Tr ₃ instead of the thermistor NTC. It is. Further, in the embodiment shown in FIG. 11 and the embodiment shown in FIG. 12, a positive temperature coefficient thermistor PTC is used to construct an Emiless protection circuit. The embodiment in FIG. 13 is a circuit example in which the present invention is applied to a discharge lamp starting device for two lamps, and includes two discharge lamps F, F' and two ballasts L,
It has L' etc. In this embodiment, the EMIRES protection circuit includes a heater _H3 and a heater _H3.
An auxiliary contact S' is provided that is opened by the curvature of the bimetal when the discharge lamp F is heated, and when the preheating time of the discharge lamp F becomes longer, the auxiliary contact S' is opened and the heater
The current flowing through H ₂ is cut off, and no preheating operation is performed.

〔Effect of the invention〕

The present invention is configured as described above, and includes a discharge lamp having a pair of filaments, an inductive ballast interposed in series between the power supply side end of the filament of the discharge lamp and an AC power supply; The first bimetal and the second
a bimetal contact, a diode inserted in series between the non-power side end of the filament of the discharge lamp and the contact, and one end connected to the connection point between the diode and the contact, and when energized, the first a first heater that heats the bimetal to open the contact;
a resistor connecting the first heater across the contact;
A constant voltage diode is connected between both ends of the series circuit of the diode and the first heater to constantize the voltage applied to the first heater via the diode, and a lighting device is used to determine whether or not the discharge lamp is lit. Since it has a discrimination circuit and a second heater which is energized by the output of the lighting discrimination circuit when the discharge lamp is not lit and which heats the second bimetal and closes the contact when the discharge lamp is energized, fluctuations in the power supply voltage can be avoided. The voltage applied to the first heater during the lighting operation of the discharge lamp is always kept constant by the constant voltage diode, even if the lamp voltage fluctuates due to changes in the discharge lamp or ambient temperature. This has the advantage that the amount of heat generated by the first heater can be made constant, and therefore the distance between the contacts can always be maintained at an appropriate distance. Furthermore, in the present invention, even if the voltage across the discharge lamp becomes as high as the power supply voltage when the power is turned off once from the lighting state and the lamp is to be turned on again immediately, the first heater The voltage applied to is stabilized by a constant voltage diode,
Therefore, if the time required to restart the discharge lamp is the same, the amount of heat generated by the second heater can be reduced, and if the amount of heat generated is the same, the time required to restart the discharge lamp can be shortened. It has the advantage of being able to

[Brief explanation of drawings]

Fig. 1a is a circuit diagram of a conventional example, Fig. 1b is a front view showing the structure of the contact used in the same, Fig. 2 is a circuit diagram of an embodiment of the present invention, and Fig. 3 is a diagram of the same at the time of starting the same. FIG. 4 is an explanatory diagram of the operation when the same as above is lit, FIG. 5 is an explanatory diagram of the operation when restarting the same as above, and FIGS. 6 to 13 are circuits showing different embodiments of the present invention. It is a diagram. 1 and 2 are bimetals, 3 is a lighting discrimination circuit, H ₁ ,
H ₂ is a heater, L is a ballast, E is an AC power supply, D ₁ is a diode, R is a resistor, and ZD is a Zener diode.

Claims (1)

[Claims] 1 Consisting of a discharge lamp having a pair of filaments, an inductive ballast interposed in series between the power supply side end of the filament of the discharge lamp and an AC power supply, and a first bimetal and a second bimetal. A diode is inserted in series between the contact, the non-power supply side end of the filament of the discharge lamp, and the contact, and one end is connected to the connection point between the diode and the contact, and when energized, the first
The first step is to heat the bimetal and open the contact.
a heater, a resistor connecting the first heater across the contacts, and a resistor connected across the series circuit of the diode and the first heater to apply a voltage to the first heater through the diode. A constant voltage diode that regulates the voltage, a lighting determination circuit that determines whether or not the discharge lamp is lit, and when the discharge lamp is not lit, it is energized by the output of the lighting determination circuit, and when energized, it heats the second bimetal and makes a contact. A discharge lamp lighting device comprising: a second heater that closes a circuit.