JPS6237520B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a discharge lamp lighting and dimming device that can adjust the preheating power of electrodes according to the dimming level.

It is common practice to adjust the lamp current by controlling the phase angle of the main thyristor for dimming inserted in series in the main circuit. A preheating current is applied to ensure stable discharge. For this purpose, a preheating transformer is provided to supply a preliminary current to the electrodes, but conventionally, the preheating current supplied by this preheating transformer is constant, and moreover, it is designed to have an optimal value when fully lit. It's normal. Therefore, when the lamp current in the main circuit decreases due to dimming operation, the filament temperature decreases, making the discharge unstable and also shortening the service life. If the preheating current is designed to be large in order to prevent this, the filament temperature will rise too much during full lighting, which will have a negative impact on the lifespan, and at the same time, the reserve power will increase, making it necessary to further increase the input power of the lighting dimmer. However, this increases power loss, and there is a problem in either case.

Figure 1 shows an example of a conventional discharge lamp lighting/dimmer device that has such problems, where 1 is a discharge lamp, 2 is a lighting circuit section, 3 is a dimmer circuit section, and 4 is a power source. . T is a lead peak type leakage transformer, _C1 is a capacitor, and these two constitute a basic circuit to which the discharge lamp 1 is connected. Note that capacitor C ₁ may not be used. A
is a preheating transformer, the primary winding A ₁ is directly connected to the power source 4, and the secondary winding A ₂ is connected to the filament 1a of the discharge lamp 1, respectively. C ₂
is a capacitor, VR is a variable resistor, and a phase shift circuit is formed by the series circuit of the two, and the midpoint is connected to the main thyristor _S1 via a silicon bilateral switch (hereinafter simply referred to as a switch) _S2 .
The main thyristor S ₁ is connected to the gate of the power supply 4 in series with the primary winding T ₁ of the leakage transformer T.
It is connected to the. Here, the main thyristor _S1 is of a bidirectional three-terminal type.

In the above circuit, the power supply voltage whose phase is controlled by the main thyristor _S1 is applied to the primary winding _T1 of the leakage transformer T, and the voltage generated in the secondary winding _T2 is superimposed to the discharge lamp 1. is applied to the discharge lamp 1, and the firing phase angle of the main thyristor _S1 is determined by the time constant determined by the capacitor _C2 and the variable resistor VR, and the capacitor _C2 is charged, and the voltage is applied to the switch S. When a switching voltage of ₂ is reached, the switch _S2 is closed and the main thyristor _S1 is triggered. By adjusting the variable resistor VR, the phase at which the main thyristor _S1 is triggered changes, and the discharge lamp 1 is dimmed. The primary winding _A1 is connected to the power supply 4 so that the preheating transformer A is not affected by this dimming.
Therefore, a constant current continues to be supplied to the filament 1a of the discharge lamp 1.

As described above, although the preheating current is prevented from decreasing during dimming in the conventional example, it is always kept constant regardless of dimming, so the preheating current is prevented from decreasing during dimming as described above. Problems such as stability, adverse effects on lifespan, and increased power loss had arisen.

The present invention was made with the aim of solving such problems in the conventional example, and includes an auxiliary secondary winding in the main circuit that increases or decreases the generated voltage according to the increase or decrease in lamp current. The secondary winding and the secondary winding of a preheating transformer that generates a constant voltage are connected in series to the filament of a discharge lamp with polarity such that their induced voltages cancel each other out.When the lamp current is large, preheating The current becomes smaller,
The preheating current is automatically adjusted according to the dimming level, so that when the lamp current is small, the preheating current is large, so there is no unstable discharge during dimming or an increase in power loss when the lamp is lit at full capacity. The present invention provides a discharge lamp lighting/dimmer device in which the life of the discharge lamp is not adversely affected by excess or deficiency of preheating current.

FIG. 2 shows an embodiment of the present invention, and the same components as those of the conventional example shown in FIG. 1 are given the same symbols and their explanations will be omitted. In this embodiment, the leakage transformer T is provided with auxiliary secondary windings T ₃ and T 3 closely coupled to the primary winding T ₁ , and these auxiliary secondary windings T ₃ and _{T 3 are} connected to the preheating transformer. Secondary winding of A
A ₂ and A ₂ are connected in series to each filament 1a and 1a of the discharge lamp 1, respectively. The auxiliary secondary winding T ₃ and the secondary winding A ₂ are connected in a depolarized manner by selecting polarities such that the induced voltages of each winding are in opposite directions and cancel each other out.

Here, when controlling the firing phase of main thyristor S ₁ to perform dimming operation, the primary winding changes depending on the phase control angle.
The voltage applied to T ₁ changes and a voltage proportional to this voltage is induced in the auxiliary secondary winding T ₃ . In other words, when the lamp current is reduced in the dimming state, the induced voltage in the auxiliary secondary winding T ₃ is small, and as it approaches full lighting, the voltage increases, so the auxiliary voltage is derived from the induced voltage in the secondary winding A ₂ . The voltage obtained by subtracting the induced voltage in the secondary winding T ₃ increases as the lamp current decreases, and decreases as the lamp approaches full lighting, and the current flowing through filament 1a increases during dimming and reaches full lighting. This results in a relationship that decreases as the distance approaches. Therefore, by appropriately selecting the specifications of each winding A ₂ and T ₃ , the filament temperature can be set to an appropriate value according to each dimming level over a wide range from full lighting to dimming. It is possible to keep it.

FIG. 3 shows an embodiment in which a leakage transformer is not used and an auxiliary secondary winding _T3 is provided in the choke coil CH, and a voltage proportional to the lamp current is generated in the auxiliary secondary winding _T3 . This voltage is small in the dimming state where the lamp current is small, and increases as it approaches full lighting. Therefore, by connecting the secondary winding A ₂ of the preheating transformer A so that the polarity is opposite to that shown in Figure 2. As in the case of , the preheating current can be automatically adjusted according to the dimming level. In addition, in the case of this example, the auxiliary secondary winding
Since the voltage generated at T ₃ is due to the lamp current, the waveform and phase are slightly different from those shown in Figure 2, so the specifications for each winding T ₃ and A ₂ must be determined taking these into account. .

Figure 4 shows an example in which _the auxiliary secondary winding T ₃ of the leakage transformer T is provided on the secondary winding T ₂ side. A voltage is generated that is a composite of the waveforms generated by the current, and this voltage becomes small in the dimming state where the lamp current is small, and increases as the lamp approaches full lighting, so the secondary winding of the preheating transformer A
By connecting the polarity opposite to A ₂ , the second
The preheating current is automatically adjusted as in the case shown in the figure. The voltage waveform generated in the auxiliary secondary winding T ₃ in this case is intermediate between the embodiment of FIG. 2 and the embodiment of FIG. 3.

As described above, the present invention applies the voltage of the auxiliary secondary winding provided in the main circuit to the voltage of the secondary winding of the preheating transformer in a depolarizing manner, so that It is possible to obtain a preheating current suitable for the dimming level of the dimming, which can prevent unstable discharge due to insufficient preheating of the filament during dimming, shorten the discharge lamp life due to too much or insufficient preheating current, or increase input power. Therefore, it is possible to obtain a discharge lamp lighting/dimmer device that is free of such problems.

[Brief explanation of the drawing]

Fig. 1 is a wiring diagram of a conventional example, Fig. 2 is a wiring diagram of an embodiment of the present invention, and Fig. 3 is a wiring diagram of another embodiment.
FIG. 4 is a wiring diagram of still another embodiment. 1 is a discharge lamp, 1a is a filament, 2 is a lighting circuit, 3 is a dimming circuit, _S1 is a main thyristor, A is a preheating transformer, _A2 is a secondary winding, _T3 is an auxiliary secondary winding It is.

Claims (1)

[Claims] 1. In a discharge lamp lighting control device that has a main thyristor for dimming that is inserted in series in the main circuit to adjust the lamp current and a preheating transformer that supplies preheating current to the electrodes of the discharge lamp, it is possible to increase or decrease the lamp current. An auxiliary secondary winding that increases or decreases the generated voltage according to the A discharge lamp lighting/dimmer device characterized in that it is connected in series to a filament of a discharge lamp with a polarity for extinguishing.