JPS5824919B2 - discharge lamp lighting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a discharge lamp lighting device that performs constant power control by controlling the firing phase angle of a bidirectional three-terminal thyristor connected in series to a high-pressure discharge lamp.

Conventionally, this type of discharge lamp lighting device is shown in Fig. 1, where 1 is a power source, 2 is a high-pressure discharge lamp, 3.4 is an inductance element, and 5 is a bidirectional three-terminal thyristor (hereinafter referred to as thyristor). 6 is a gate control circuit that detects the lamp voltage VVa and controls the firing phase angle of the thyristor 5, and this gate control circuit 6 increases the conduction angle of the thyristor 5 as the lamp voltage Vla increases. It moves in the direction.

Further, as the lamp voltage Vla decreases, the conduction angle of the thyristor 5 becomes smaller.

The operation of the gate control circuit 6 having this function will be explained.

Describing the mixed starting process, when the power source 1 is turned on now, the high pressure discharge lamp 2 starts glow discharge, and the high pressure discharge lamp 2 becomes short-circuited.Therefore, since there is almost no resistance component in the circuit, the current flows to the high pressure discharge lamp 2. The current is 9 for the power supply 1
The delay current is close to 0 degrees.

Therefore, the on-phase of the thyristor 50 needs to be 90 degrees or more.

On the other hand, if thyristor 5 is not turned on at the initial stage of starting, 1-4-3
The current flowing through the high-pressure discharge lamp 2 at startup is small, and sufficient current for the lamp voltage V/a to rise cannot be obtained, and the current when the high-pressure discharge lamp 2 is short-circuited If is too small, the time required to transition from glow discharge to arc discharge becomes longer, stress on the high pressure discharge lamp 2 increases, and there is a problem in that it tends to shorten the lifespan due to promotion of blackening.

However, in order to solve this problem, it is necessary to turn on the thyristor 5 from the initial stage of startup to flow an appropriate current to hasten the transition from glow discharge to arc discharge and to shorten the startup time.

In the conventional example, when the high-pressure discharge lamp 2 shifts from glow discharge to arc discharge, the lamp voltage V/a increases and the circuit current decreases, but the gate control circuit 6 prevents the lamp voltage V/a from increasing. Since the firing phase angle of the thyristor 5 is controlled to advance accordingly, the current does not decrease and shifts to a predetermined lamp voltage V/a, resulting in steady lighting.

That is, as the lamp voltage Vla increases, the resistance component of the circuit increases and the phase of the lamp voltage V/a advances, so that the firing phase angle of the thyristor 5 is controlled to advance.

By the way, when trying to achieve, for example, constant power during steady lighting, if the high-pressure discharge lamp 2 is capable of achieving constant power by performing phase control in the direction of increasing the lamp current Ila as the lamp voltage V/a increases. As in the starting process, the ignition phase angle of the thyristor 5 is controlled to advance as the lamp voltage VVa increases, and on the other hand, when the lamp voltage V/a decreases, the ignition phase angle changes in the opposite direction.

Therefore, constant power control can be achieved by controlling the phase between the starting process and steady lighting by detecting the lamp voltage V/a and changing the ignition phase of the thyristor 50 according to its magnitude.

However, as shown in Figure 2a, the lamp voltage V/a
There is a problem that constant power control of a so-called saturated vapor pressure type (positive characteristic) high pressure discharge lamp 2 such as a high pressure sodium lamp cannot be achieved only by a control method in which the ignition phase angle θ advances as the ignition phase angle increases. there were.

In other words, in the high pressure discharge lamp 2 of an unsaturated vapor pressure type such as a high pressure mercury lamp or a metalnolide lamp, the filler (such as mercury) in the two lamp tubes has been completely evaporated, so the condition inside the lamp tube is similar to that of the high pressure discharge lamp 2. Even if the input power increases, the lamp voltage V/a hardly changes.If Vla-0 is set to the relationship shown in FIG. 2a, the lamp power can be kept constant.

However, in a saturated vapor pressure type high-pressure discharge lamp 2 such as a high-pressure sodium lamp, there is an excessive amount of filler (sodium) inside the lamp tube, so the inside of the lamp tube is in a saturated state even during normal operation, and the high-pressure discharge lamp 2 is in a saturated state. As the input power increases, the temperature of the coldest point of the lamp tube increases and the lamp voltage Vla
As the lamp voltage VVa increases, it is necessary to control the ignition phase angle θ to delay the ignition phase angle θ and suppress the input power to the high-pressure discharge lamp 2 (control as shown in FIG. 1). There was a problem in that constant power control could not be achieved by setting -θ to the relationship shown in FIG. 2a.

Note that Figure 2 a shows the relationship between the lamp voltage V/a and the ignition phase angle θ of the thyristor 5. Point 8 is the ignition phase angle that turns on at the beginning of startup, and point b is the lamp voltage at steady state. V/a
indicates the ignition phase angle, and as the lamp voltage VVa increases, the ignition phase angle θ moves toward the advance side.

The figure shows the gate trigger signal VT of the thyristor.

In addition, Utility Application No. 113408/1982
As seen in Publication No. 670), there is a conventional method in which a high-pressure discharge lamp such as a high-pressure sodium lamp is lit at constant power by controlling the ignition phase angle of a thyristor using the lamp current and lamp voltage. In this case, the firing phase angle of the thyristor is set based on a composite control input that is a combination of two types of control inputs (lamp voltage detection section output and lamp current detection section output) both at startup and during steady state. Therefore, there was a drawback that it was difficult to design the gate control circuit.

In other words, selecting the circuit constants of the gate control circuit while always taking into account the combined control input from detection of the lamp current and lamp voltage of the high-pressure discharge lamp during startup or steady state is a very troublesome task, and it is difficult to design the circuit. There was a problem.

The present invention aims to solve the above problems.

Examples will be described below using figures.

FIG. 3 shows a block circuit diagram of an embodiment of the present invention, in which 1 is a power source, 2 is a saturated vapor pressure type high pressure discharge lamp such as a high pressure sodium lamp, 3 and 4 are inductance elements,
5 is Cyrisk, 6 is a gate control circuit, 1 is a power supply section for the control section, 8 is a trigger signal generation section for the thyristor, 9 is a lamp voltage detection section, 10 is a lamp current detection section, and R is a resistor for lamp current detection. be.

FIG. 5 shows temporal changes in lamp current I/a and lamp voltage VVa from starting to steady lighting of the high-pressure discharge lamp 2 with this configuration.Lamp voltage Vla increases with time and lamp current I /a determines the firing phase angle θ of the thyristor 50 so that it has an appropriate value at the initial stage of startup, and advances the firing phase angle θ so that the lamp current Ila gradually decreases as the lamp voltage Vla increases. , when the lamp current I/a becomes less than a certain value, for example, AB in FIG.
The reason for this is that the ignition phase angle is determined by the detection level of the lamp voltage vla.
As the lamp voltage 'Wa increases, the lamp current I/a decreases, and the lamp voltage V/a becomes constant at a stable point.

FIG. 6 shows changes in the detection level corresponding to FIG. 5.

In FIG. 6, tl is the detection level of the lamp current I/a mainly at the time of starting, and t2 is the detection level of the lamp voltage Vla during steady lighting.

The overall operation of the gate control circuit 6 is such that when the detection level increases, the phase lags, and when the detection level decreases, the phase advances.As the detection level changes as shown in FIG. 6, the gate control circuit 6 operates as a ramp as shown in FIG. The gate trigger signal VT of the thyristor 5 having a relationship between the voltage Vla and the firing phase angle θ is output, and when the lamp voltage Vj'a becomes equal to or higher than the specified value, that is, when the 24 lamp current Ila becomes equal to or less than the specified value, the lamp voltage V As /a increases, the ignition phase angle θ changes in the direction of delay.

Further, the gate control circuit 6 is configured such that the ignition phase angle θ based on the lamp current Ila and the ignition phase angle θ based on the lamp voltage V/a at the time when the lamp voltage vla reaches a specified voltage are approximately equal. Therefore, the firing phase angle θ of the thyristor 50 changes continuously from the time of starting to the time of steady lighting, and stable operation can be obtained.

FIG. 4 shows a specific circuit example of the gate control circuit 6.
The operation will be explained below.

R1 to R6 are resistors, zD1 to ZD3 are Zener diodes, C1 is a capacitor, PUT is a programmable unijunction transistor, and Tr is a transistor, which are used to synchronize the power supply.

PT is similar to the gate trigger signal of thyristor 5.

Now, when PUT is turned on by comparing the voltage of capacitor C1 and the voltage of resistor R4, the charge of capacitor C1 becomes PUT.
is emitted to the cathode of the anode A-PUT in a closed circuit of one pulse transformer PT, and a trigger signal is given to the thyristor 5 by the pulse transformer PT.

First, in the starting process, after turning on power 1, 1-4-
The high-pressure discharge lamp 2 starts discharging in the closed circuit of 3-2, a current flows, and when the lamp current I/a is detected, the detection level is immediately determined and the voltage of the resistor R4 and the voltage of the capacitor C1 are compared. As a result, PUT is turned on and thyristor 5 is turned on.

At this time, since the lamp voltage V/a is low, the voltages across the resistors R3 and R4 are determined by the detection level of the lamp current I/a.

As the lamp voltage vla increases, the lamp current I/a slightly decreases while the ignition phase angle θ advances, and the lamp current I/a
When the lamp current I/a decreases to a certain value, the detection of the lamp current I/a is cut off and the ignition phase angle θ is gradually determined by the detection level of the lamp voltage Vla.

During steady lighting, it is determined only by the detection level of the lamp voltage VVa, so if the lamp voltage Vla increases for some reason, the lamp operates in the direction of decreasing the lamp current I/a, that is, in the direction of delaying the ignition phase angle θ. Therefore, with this kind of control, it is possible to realize constant power for the discharge lamp.

FIG. 8 shows another embodiment, in which a timer part 11 is used to convert the output of the timer part 11 into the lamp current I shown in FIG.
It corresponds to the detection level of la, and is designed to achieve the same function.

; FIG. 9 shows still another embodiment in which a secondary winding 3' is provided in the inductance element 3 to control the lamp current I/a.
, and the lamp voltage V/a is used to smoothly and continuously perform phase control at the time of starting.

As described above, the present invention performs constant power control by controlling the firing phase angle of a thyristor connected in series to a saturated vapor pressure type high-pressure discharge lamp, and connects an inductance element to the thyristor in parallel to achieve high-pressure discharge. A discharge lamp designed to prevent the lamp from going out; in a lighting device, the ignition phase angle of the thyristor is controlled based on the lamp current when the lamp voltage is started when the lamp voltage is below a specified value, and when the lamp is lit steadily when the lamp voltage is above the specified value. Provides a discharge lamp lighting device that has a thyristor gate control circuit configured to control the firing phase angle of the thyristor based on the lamp voltage, has good starting characteristics, and can easily control constant power during steady lighting. can,
Moreover, since two types of control inputs (lamp current detection output and lamp voltage detection output) are switched depending on whether the lamp voltage is below or above a specified value, it has the effect of simplifying the circuit design of the gate control circuit. are doing.

In other words, if the thyristor is controlled based only on the lamp current, the firing phase angle of the thyristor will be delayed when the lamp current is large, so the lamp current immediately after starting can be suppressed and the starting characteristics will be improved. Since the lamp current is almost constant during steady lighting, it is difficult to perform constant power control.On the other hand, if the thyristor is controlled based only on the lamp voltage, constant power control during steady lighting is difficult.
(","In a saturated vapor pressure discharge lamp, the lamp current remains approximately constant despite fluctuations in the power supply, but the lamp voltage varies greatly.
The lamp power changes by the same degree as the lamp voltage.

) However, since the lamp voltage immediately after starting is almost Ov, the thyristor firing phase angle advances and the input current becomes very large.

Therefore, as in the present invention, by controlling the ignition phase angle of the thyristor based on the lamp current during starting and based on the lamp voltage during steady lighting, good starting characteristics can be achieved and the constant power consumption during steady lighting can be improved. Therefore, it is possible to provide a discharge lamp lighting device that can be easily controlled.

In addition, it is possible to determine whether it is starting or steady lighting based on the lamp voltage, and to control the thyristor based on the lamp current during starting, and to control the thyristor based on the lamp current during steady lighting, and control in each state. Since the input is selected, the control input and the control state (firing phase angle of the thyristor) need only correspond 1:1, which has the effect of simplifying the circuit design of the gate control circuit. There is.

Furthermore, by making the firing phase angle of the thyristor based on the lamp current and the firing phase angle of the thyristor based on the lamp voltage approximately equal at the time when the lamp voltage reaches the specified voltage, the point from starting to steady lighting is improved. This has the effect that the arc phase angle can be changed smoothly and stable lighting operation can be performed.

[Brief explanation of drawings]

Fig. 1 is a block circuit diagram of the conventional example, Fig. 2 is an explanatory diagram of the same as above, Fig. 3 is a block circuit diagram of an embodiment of the present invention, Fig. 4 is a specific circuit diagram of the same as above, and Figs. FIG. 8 is a block circuit diagram of another embodiment, and FIG. 9 is a block circuit diagram of still another embodiment. 1 is an AC power supply, 2 is a high-pressure discharge lamp, 3 and 4 are inductance elements, 5 is a bidirectional three-terminal thyristor, and 6 is a gate control circuit.

Claims (1)

[Claims] 1. A high-pressure discharge lamp in which two inductance elements and a saturated vapor pressure type high-pressure discharge lamp are connected in series to an AC power source, and a bidirectional three-terminal thyristor is connected in parallel to one inductance element. In a discharge lamp lighting device that performs constant power control by controlling the ignition phase angle of the bidirectional three-terminal sirisk based on the voltage and lamp current, the bidirectional control is performed when the lamp voltage is lower than a specified voltage. The firing phase angle of the bidirectional three-terminal thyristor is controlled based on the lamp current, and the firing phase angle of the bidirectional three-terminal thyristor is controlled based on the lamp voltage during steady lighting when the lamp voltage is higher than the specified voltage. A discharge lamp lighting device comprising a gate control circuit of a tropic three-terminal thyristor. 2 The firing phase angle of the bidirectional 3-terminal thyristor based on the lamp current at the time when the lamp voltage reaches the specified voltage is made approximately equal to the firing phase angle of the bidirectional 3-terminal thyristor based on the lamp voltage. 2. The discharge lamp lighting device according to claim 1, further comprising a bidirectional three-terminal silice gate control circuit.