JPH0367319B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a discharge lamp lighting device for lighting a saturated vapor pressure discharge lamp.

Figure 1 shows the circuit configuration of a basic discharge lamp lighting device that controls the phase of a saturated vapor pressure discharge lamp 2, such as a high-pressure sodium lamp, using a bidirectional three-terminal thyristor _Q1 , which is a phase control element. ing. In the figure, L ₁ is the main current-limiting inductance, and L ₂ is the high-impedance auxiliary inductance for preventing power out. 3 is a control circuit for controlling the phase of the thyristor _Q1 and controlling the bidirectional three-terminal thyristor _Q2 of the starting means. However, in this basic circuit, a bidirectional three-terminal thyristor is used during starting.
Q ₁ and a bidirectional three-terminal thyristor Q ₂ as a starting means.
are turned on at the same time, and a pulse is applied to the closed circuit of the AC power supply 1, the bidirectional 3-terminal thyristor Q ₁ , the portion L ₁₁ up to the tap of the main limiting inductance L ₁ , the capacitor C ₁ , and the bidirectional 3-terminal thyristor Q ₂ The discharge lamp 2 is activated by applying a current to both ends of the main limiting current inductance _L1 to induce a high voltage pulse and superimposing it on the voltage Vs of the AC power supply 1, and applying the superimposed voltage to both ends of the discharge lamp 2. This will lead to the start.
When the discharge lamp 2 lights up, the control circuit 3 adjusts the tube voltage V _la
By detecting this, the bidirectional three-terminal thyristor _Q2 is turned off, and the phase of the bidirectional three-terminal thyristor _Q1 is controlled to perform constant power and constant tube voltage control. [VA]
can be reduced by about 2/3 to 4/5, making the device smaller and lighter.

By the way, the control circuit 3 has conventionally been provided with a circuit configuration as shown in FIG. This circuit detects the tube voltage V _la by dividing it using resistors Ra and Rb, which are detection means, and determines and controls the conduction angle θ of the bidirectional three-terminal thyristor Q ₁ corresponding to the tube voltage V _la . The relationship is shown in FIG. In other words, θ ₁ shown in Fig. 3 indicates the conduction angle immediately after the discharge lamp 2 is lit, and θ ₂ is the stop angle that prevents the conduction angle from turning off due to a delay when the tube voltage V _la increases. , θ ₂ , a ₁ to θ ₂ , a ₂ , the phase control operation at this conduction angle is continued. Above θ ₂ , a ₂ is the no-load state V _la ≈Vs, which is the region in which the bidirectional three-terminal thyristor Q ₂ operates. In other words, the tube voltage V _la
When becomes more than a ₂ , the bidirectional three-terminal thyristor
This is the region where Q ₂ operates and generates a high voltage pulse across the inductance L ₁ . Further, from θ ₁ to θ ₃ is a warm-up region where the discharge lamp 2 is started and then shifted to steady lighting. Further, from θ ₃ to θ ₂ indicates a region where constant power and constant tube voltage control is performed during steady lighting. In this way, the control circuit 3 shown in FIG. 2 has a conduction angle θ and a tube voltage V _la shown in FIG.
A bidirectional three-terminal thyristor with a relationship with
Control Q ₁ and Q ₂ .

Next, the configuration and operation of the circuit shown in FIG. 2 will be explained.
In the figure, 4 is a timer IC (for example, μpc1555c manufactured by NEC) which is a phase control means.
When the terminal voltage of the capacitor C ₅ (corresponding to the second capacitor in the claims) connected to the threshold terminal reaches 2/3 of the terminal voltage Vc ₂ of the capacitor C ₂ which is the power supply, the IC 4 outputs an output signal. Both the terminal and terminal are at “L” level,
The charge stored in the capacitors C ₃ and C ₄ connected to each other is transferred to the capacitor C ₃ and the diode.
D ₃ , output terminal, ground terminal, pulse transformer
The circuit of the primary winding of PT ₁ , the capacitor C ₄ , the terminal, the ground terminal, the diode D ₂ , and the circuit of the primary winding of pulse transformer PT ₂ cause the discharge to occur in the secondary of pulse transformer PT ₁ , which is the trigger generation means. The output of the winding and the secondary winding of the pulse transformer PT ₂ causes each bidirectional three-terminal thyristor Q ₁ and Q ₂ to be ignited and conductive. At the same time, the charge in the capacitor C ₅ is discharged through a circuit including the diode D ₄ , the output terminal, and the ground terminal. The charging start time of capacitors C ₃ , C ₄ , and C ₅ is the falling point when the voltage applied to the trigger terminal becomes 1/3 of the voltage Vc ₂ of capacitor C ₂ , and this applied voltage is equal to the voltage Vs of AC power supply 1. Since the voltage of the resistor R ₂ is obtained by dividing the voltage proportional to the voltage by the resistors R ₁ and R ₂ , a charging start point synchronized with the cycle of the AC power supply 1 can be obtained.

Now, when the discharge lamp 2 is started, the tube voltage V _la and the voltage Vs of the AC power supply 1 are equal, so the voltage across the resistor Rb of the tube voltage V _la detection means is high, and the Zener diodes ZD ₃ and ZD ₂ are both conductive. state. Resistor R ₉ connected in series with Zener diode ZD ₃ ,
A voltage is generated in the voltage divider circuit of _R10 , turning on the transistor _Q3 , and connecting the resistor _R4 , capacitor _C4 ,
Current flows through the circuit of transistor _Q3 and the capacitor
_C4 is charged, capacitor _C3 is charged through resistor _R3 , and capacitor _C5 is charged through resistor _R5 . When the terminal voltage Vc ₅ of capacitor C ₅ exceeds the threshold voltage, the timer
IC4 operates to discharge the charges in each capacitor C ₃ and C ₄ in the circuit described above, and each pulse transformer
The pulse voltages generated from PT ₁ and PT ₂ cause each bidirectional three-terminal thyristor Q ₁ and Q ₂ to ignite and conduct. Due to the conduction of the bidirectional three-terminal thyristor _Q2 , a high-voltage pulse is generated at both ends of the main current-limiting inductance _L1 , and the discharge lamp 2 is started and lit. Now, when the discharge lamp 2 starts and lights up, the tube voltage V _la becomes about 20 to 30 V, so the terminal voltage of the capacitor C ₆ (corresponding to the first capacitor in the claims) Vc ₆
decreases and becomes below the Zener voltage of the Zener diode ZD ₃ , the Zener diode ZD ₃ does not conduct and therefore the transistor Q ₃ also turns off and the charging of the capacitor C ₄ also stops, resulting in bidirectionality 3
The triggering of the terminal thyristor Q ₂ is also stopped, the bidirectional three-terminal thyristor Q ₂ is turned off, and the high voltage pulse that was generated across the inductance L ₁ is also no longer generated. By the way, during the starting process, as the voltage V _CE of capacitor C ₆ rises, capacitor C 5 is also charged by the closed circuit of capacitor C ₆ , resistor R ₇ , diode D ₆ , and capacitor C ₅ , so the timer _is activated.
The time for the voltage applied to the threshold terminal of the IC 4 to reach the threshold level, that is, 2/3Vc ₂ becomes faster, and the transition operation from θ ₁ to θ ₃ in FIG. 3 is performed. When the terminal voltage Vc ₆ of the capacitor C ₆ increases, it becomes larger than the Zener voltage of the Zener diode ZD ₁ , and the Zener diode ZD ₁ becomes conductive, and the charging speed of the capacitor C ₅ is fixed at this point. That is, the Zener diode ZD ₁ functions as a control means. This fixed point corresponds to θ ₃ , and the voltage Vc ₆ of the capacitor C ₆ at this time is about 2/3 of the capacitor Vc ₂ .

Now, when the discharge lamp 2 shifts to steady lighting (that is, in the section from θ ₃ to θ ₂ ) and the voltage Vc ₆ of the capacitor C ₆ becomes even higher, the control voltage terminal of the timer IC 4 starts contributing to the operation. Capacitor C ₅ serves to raise the threshold level corresponding to the voltage Vc ₅ , and capacitor C ₆ , resistor R ₆ ,
Diode D ₅ , control voltage terminal,
By the function of the threshold level control means consisting of the ground terminal circuit, the capacitor
The operation of timer IC4 is delayed in response to the rise in voltage _Vc6 of _C6 , and as a result, the firing phase of bidirectional three-terminal thyristor _Q1 is delayed. In other words, the conduction angle from θ ₃ to θ ₂ in FIG. 3 is controlled.

As described above, the control circuit 3 of the conventional example shown in FIG. 2 controls the bidirectional three-terminal thyristors Q ₁ and Q ₂ according to the tube voltage V _la of the discharge lamp 2.
However, this conventional example has the following drawbacks.

In other words, when the bidirectional three-terminal thyristor Q ₂ is operating at the time of starting, that is, when the starting means is operating, the phase of applying the high-voltage pulse to the discharge lamp 2 is set at a conduction angle θ ₂ to prevent it from going out. Therefore, it was not possible to apply a high-voltage pulse to the discharge lamp 2 at a phase that is easy to start. The inventor's experiments have shown that the higher the high-voltage pulse generation phase is advanced, the easier it is to start, and the lower the voltage required for starting, compared to the power supply phase, which is easier to start.
In addition, in view of this point, in the conventional circuit, if the conduction angle θ ₂ corresponding to the limit phase for preventing power-off is set to the front side, the power-off and starting characteristics become better, but the control width between the conduction angle θ ₃ and θ ₂ is very large. The drawback was that it was narrow. In this way, if the conduction phase for preventing flash-off is made the same as the generation phase of the high-voltage pulse for starting and lighting, there will be problems in terms of starting performance, control ability, etc. Therefore, the applied voltage of the high-voltage pulse will have to be increased. This was necessary, and the pressure resistance of each part also caused an increase in costs. In the figure _, DB _{1 and} DB ₂ are full-wave rectifiers, D ₁ is a diode _, T ₁ is a step-down transformer, and R ₈ is a resistor _. A power supply means for rectifying and smoothing an alternating current voltage proportional to the voltage of 1 is constructed.

The present invention has been made in view of the above-mentioned drawbacks.
The purpose of this is to improve starting performance, reduce the applied starting voltage, lower the withstand voltage performance of the elements used, improve turn-off performance, and reduce the conduction angle during steady lighting. An object of the present invention is to provide a discharge lamp lighting device that can widen the control range.

The present invention will be explained below with reference to Examples.

FIG. 4 is a circuit diagram showing a control circuit 3 of an embodiment, in which a series circuit of a resistor R ₁₁ and a diode D ₇ is connected between the anode of a diode D ₅ and the collector of a transistor Q ₃ . The inserted configuration is added to the conventional circuit shown in FIG. In other words, to explain based on FIG. 5, in the figure θ ₂ ,
The section from a ₁ to θ ₂ , a ₂ is a section for preventing power out, and when the tube voltage V _la is between a ₁ and a ₂ , the operation is the same as that of the conventional example shown in FIG. When _la becomes more than a point ₂ (that is, no load condition), Zener diode ZD ₃ becomes conductive and transistor Q ₃ turns on. On the other hand, around the control voltage terminal, there is a closed circuit of capacitor C ₆ , resistor R ₆ , resistor R ₁₁ , diode D ₇ , transistor Q ₃ , and capacitor
Since a closed circuit of C ₆ , resistor R ₆ , diode D ₅ , control voltage terminal, and ground terminal is formed, the voltage applied to the control voltage terminal is the voltage Vc ₆ of capacitor C ₆ and resistor R ₆ and R ₁₁
As a result, the voltage at the control voltage terminal is lower than that of the conventional circuit. That is, compared to the conventional configuration, by adding the resistor _R11 and the diode _D7 , the threshold level can be lowered when the tube voltage rises to the AC power supply voltage. As a result, the threshold level of timer IC4 decreases, and the controlled conduction angle θ advances forward. In other words _, the phase advanced before this is _{θ 4} shown in FIG.
It is applied to both ends of . The process from starting to steady lighting and the operation in the steady lighting period from θ ₃ to _{θ 2} are the same as those in the conventional example shown in FIG. 2, and their explanation will be omitted.

FIG. 6 shows a control circuit 3 according to another embodiment of the invention, which includes a resistor R ₁₂ between the anode of the Zener diode ZD ₂ and the negative line.
Connect the series circuit of R ₁₃ and also connect the diode
Resistor R ₁₄ between the anode of D ₅ and the negative line
A circuit is added to the circuit shown in FIG. 2, in which a transistor Q ₄ is connected through the transistor Q ₄ and the base of the transistor Q 4 is connected to the connection point between the resistors R ₁₂ and R ₁₃ . In this embodiment, when the voltage Vs of the AC power supply 1 suddenly changes and decreases, the lamp current of the discharge lamp 2 decreases, and the tube voltage _Vla increases due to the negative characteristic. And the voltage of a ₁ in Fig. 7 is the tube voltage V _la
When the voltage rises, the Zener diode ZD ₂ becomes conductive and the transistor Q ₄ is turned on, and the voltage Vc ₆ of the capacitor C ₆ is divided by the resistors R ₆ and R ₁₄ to lower the voltage applied to the control voltage terminal, and the voltage applied to the control voltage terminal is reduced. The voltage level is lowered, and the conduction angle θ of the bidirectional three-terminal thyristor _Q1 is set in a direction that increases the lamp current, thereby suppressing the increase in the tube voltage _Vla . Also, when the tube voltage V _la is reached at _two or more points a shown in Figure 7,
Correspondingly, the Zener diode ZD ₃ conducts, turning on the transistor Q ₃ and re-triggering the bidirectional three-terminal thyristor Q ₂ as before, generating a high-voltage pulse across the inductance L ₁ . Therefore, the voltage is applied to the discharge lamp 2.

The present invention provides a discharge lamp lighting device configured as described above, in which when the tube voltage rises to the AC power supply voltage after transition to steady lighting, the phase AC control element and the starting means are activated at a phase before the conduction phase to be restricted. As a result, the starting performance can be improved, the starting voltage applied can be reduced, the voltage resistance of the parts used can be lowered, costs can be reduced, and the control range during steady lighting can be widened.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of a basic discharge lamp lighting device, Fig. 2 is a specific circuit diagram of a conventional control circuit, Fig. 3 is an explanatory diagram of the same operation, and Fig. 4 is an embodiment of the present invention. 5 is an explanatory diagram of the same operation as above, FIG. 6 is a concrete circuit diagram of a control circuit of another embodiment of the present invention, and FIG. 7 is an explanatory diagram of the operation of is an AC power supply, 2 is a discharge lamp, _L1 is a main current limiting inductance, 3 is a control circuit, 4 is a timer IC,
Q ₁ , Q ₂ are bidirectional three-terminal thyristors, PT ₁ ,
PT ₂ is a pulse transformer, Q ₃ is a transistor, ZD ₁
~ZD ₃ is a Zener diode, C ₅ is a capacitor.

Claims (1)

[Claims] 1 A main circuit formed by connecting an AC power supply with a series circuit of an AC phase control element, a main current limiting inductance, and a saturated vapor pressure discharge lamp, and a starting circuit that generates a high-voltage pulse for starting at both ends of the discharge lamp. and a first trigger pulse generating means for triggering the starting means, a second trigger pulse generating means for triggering the AC phase control element, and detecting the voltage across the discharge lamp and rectifying the detected voltage. a first capacitor charged with a voltage obtained by
detecting means for generating a detection output that enables the second trigger pulse generating means to operate if the voltage of the capacitor is equal to or higher than the voltage corresponding to the no-load voltage; a power supply means, an output of the power supply means and the first power supply means;
A second capacitor charged with the voltage across the capacitor and the output of the power supply means are used as power supplies, and when the voltage of the second capacitor exceeds a threshold level, the first trigger pulse generation means is operated. and a phase control means for activating the second trigger pulse generation means and forming a discharge circuit for the second capacitor when detecting that the AC voltage has dropped to a constant level set lower than the threshold level; Threshold level control means for applying a control voltage to the phase control means to raise and lower the threshold level of the phase control means using the voltage of the first capacitor; In a discharge lamp lighting device that controls a discharge lamp at a constant input and a constant tube voltage, the device includes a control circuit that limits the voltage at which the second capacitor is charged from the first capacitor to a constant voltage, and controls the discharge lamp at a constant input and a constant tube voltage.
A means for lowering the threshold level is added to the control circuit so that when the tube voltage rises to the AC power supply voltage, the phase control means operates both trigger pulse generation means at a phase before the conduction phase limited by the control means. A discharge lamp lighting device characterized by comprising: