JPH0644516B2 - Discharge lamp starter - Google Patents

Description

The present invention relates to a discharge lamp starting device for lighting a high / low pressure discharge lamp in combination with a phase advance ballast.

[Conventional technology]

The phase-advancing ballast has been used in recent years as a ballast for discharge lamps because it exhibits excellent characteristics with respect to fluctuations in power supply voltage, extinguishing characteristics, and the like. FIG. 5 is a circuit diagram of a conventional discharge lamp starting device combined with such a phase-advancing ballast. In FIG. 5, 1 is an AC power source, 2 is a magnetic leakage transformer, 3
Is a capacitor, 4 is a discharge resistor, 5 is a bidirectional two-terminal semiconductor switching element, for example, SSS (Silicon symmet).
rical switch), 6 is a condenser, and 7 is a discharge lamp.

The operation of the conventional discharge lamp starting device will be described below with reference to FIG. FIG. 6 is a pulse generation state diagram of a conventional discharge lamp starting device.

The AC power supply 1 is applied and the voltage applied to SSS5 is SSS.
When the breakover voltage Vb of 5 is reached, the SSS 5 rapidly becomes conductive. At this time, due to the inductance of the magnetic leakage transformer 2, a positive high voltage pulse is generated at point A in FIG. Then, SSS5 temporarily shifts to the non-conducting state at the zero cross point B of the power supply voltage. Next, the power supply voltage is reversed and S
When a reverse voltage is applied to SS5, a negative high voltage pulse is similarly generated at point C in FIG. Hereinafter, positive and negative high voltage pulses are generated in each cycle of the sine wave AC power supply, and the discharge lamp is lit by the high voltage pulses. The generation position of this high-voltage pulse can be changed by appropriately selecting the value of the breakover voltage Vb of SSS5. The discharge resistor 4 is for discharging the electric charge accumulated in the capacitor 3 after the discharge lamp 7 is turned off to avoid the adverse effect of the residual electric charge on the human body.

[Problems to be solved by the invention]

By the way, generally, there is a current phase (a phase slightly after the zero crossing point of the load current) that is easy to start in order to light the discharge lamp, and if a high-voltage pulse is applied at that time, it is extremely easy to light the discharge lamp. You can The phase control for generating such a high voltage pulse can be easily performed in the case of the delay type ballast using the choke coil. However, when a phase-advancing ballast is used, it is not easy to control the phase for generating such a high voltage pulse.

FIG. 7 is an operation waveform diagram when a phase-advancing ballast is used. In FIG. 7, V ₀₂ is a no-load waveform, V ₂ is a load voltage waveform, and I ₂ is a load current waveform. In the case of a phase-advancing type ballast using a capacitor, as shown in FIG. 7, the load current I ₂ leads the secondary no-load voltage V ₀₂ (about 40%).
Degree). Therefore, at a phase slightly beyond the position where the load current I ₂ becomes zero, for example, at point P in FIG.
By applying a high-voltage pulse in the same direction as the load current I ₂ , the discharge lamp can be reliably turned on.

However, in the conventional discharge lamp starting device, even if the breakover voltage Vb of SSS5 is changed, a pulse cannot be generated at a position advanced from the zero cross point of the no-load voltage which is in phase with the power supply voltage. It was not easy to light a discharge lamp using a ballast.

The present invention has been made based on the above circumstances, and an object of the present invention is to provide a discharge lamp starting device capable of easily and reliably lighting a discharge lamp using a phase-advance ballast.

[Means for solving problems]

The present invention for achieving the above object, in a discharge lamp starting device for lighting a discharge lamp by an AC power supply, in combination with a phase advance type ballast having a capacitor, for applying an adjustable bias voltage to the AC power supply. A bias circuit provided at the output end of the phase-advancing ballast, and a pulse generation circuit including a semiconductor switching element and connected in parallel with the discharge lamp are provided, and by changing the value of the circuit element of the bias circuit, The bias voltage applied to the AC power supply is changed to generate at least one of positive and negative pulses by sequentially changing its phase for each cycle of the AC power supply.

[Action]

According to the present invention, an adjustable bias voltage is applied to the AC power supply by using the capacitor used in the phase-advanced ballast by the above-mentioned means, and the semiconductor switching element suddenly becomes conductive in each cycle of the AC power supply. The position of the pulse generated at this time can be gradually changed in each cycle of the AC power supply according to the charge amount of the capacitor. Further, by appropriately changing the bias voltage and the breakover voltage of the semiconductor switching element, it is possible to easily control the generation start position and the generation end position of the generated pulse.
This makes it possible to generate a pulse in the same direction as the load current at a position slightly delayed from the zero cross point of the load current for each cycle of the AC power supply, so that a discharge lamp combined with a phase-advanced ballast can be easily and easily It can be reliably turned on.

〔Example〕

A discharge lamp starting device according to an embodiment of the present invention will be described below with reference to FIGS. 1 to 4. FIG. 1 is a circuit diagram of a discharge lamp starting device which is an embodiment of the present invention. In FIG. 1, those having the same functions as those in FIG. 5 are designated by the same reference numerals, and detailed description thereof will be omitted. In FIG. 1, P
T is a pulse transformer, p is a primary winding of the pulse transformer PT, s is a secondary winding of the pulse transformer PT, D is a diode, Cp is a bypass capacitor, Cr is a pulse width adjusting capacitor, and Rn is a capacitor. 3 discharge resistance, R
f is a fuse function and a resistor for adjusting the maximum allowable current of SSS5, Rc is a resistor forming a charge / discharge circuit of the capacitor 3,
TR is a timer, and tr is a contact of the timer TR.

Next, the operation of the discharge lamp starting device configured as described above will be described with reference to FIGS. 2 to 4. Now S
It is assumed that the sum of the breakover voltage Vb of SS5 and the charging voltage Vi (hereinafter also referred to as a bias voltage) to the capacitor 3 is set to be smaller than the maximum value Vm of the sine wave AC power supply. FIG. 2 is a pulse generation state diagram at this time. When the AC power supply 1 is turned on, the sine wave AC power supply 1
The voltage of the first positive half cycle is applied through the capacitor 3 to the series circuit including the primary winding p of the pulse transformer PT, the resistor Rf, the capacitor Cr, the SSS5 and the contact tr. The voltage applied to SSS5 is SSS5.
When the voltage becomes equal to or higher than the breakover voltage Vb, the SSS5 rapidly becomes conductive. At this time, due to the inductance of the magnetic leakage transformer 2, a positive high voltage pulse is generated at point X _{1 in} FIG. Then, SSS5 temporarily transits to the non-conducting state at the zero cross point of the power supply voltage. Next, when the power supply voltage is inverted and a reverse voltage is applied to SSS5, a negative high voltage pulse is similarly generated at point X _{2 in} FIG. 2 even in the positive half cycle. Also, in this negative half cycle,
A charging current flows through the capacitor 3 through the charging / discharging resistor Rc and the diode D, and charging is performed in the direction shown in FIG.

Next, when a voltage of the second positive half cycle is applied to the series circuit through the capacitor 3, the capacitor 3 is charged during the first negative half cycle as shown in FIG. The applied voltage becomes equal to or higher than the breakover voltage Vb of SSS5 later than in the first positive half cycle. Therefore, the phase of the high-voltage pulse generated in the second positive half cycle is slightly delayed from the generation start phase X ₁ of the high-voltage pulse generated in the first positive half cycle. In the second negative half cycle, the voltage obtained by adding the sine wave voltage to the charging voltage Vi of the capacitor 3 is added to the series circuit, so that the voltage applied to SSS5 is SSS5.
It becomes faster than the breakover voltage Vb of 5 than in the first negative half cycle. Therefore, the phase of the high voltage pulse generated in the second negative half cycle is the first
Slightly ahead of the generation start phase X ₂ of the high voltage pulse generated during the negative half cycle of Further, the capacitor 3 is charged in the second negative half cycle, and its charge amount is slightly larger than the charge amount in the first negative cycle. Here, the charging amount of the capacitor 3, that is, the degree of the DC bias is determined by the charging circuit of the capacitor 3 including the resistor Rc and the diode D and the discharging circuit including the resistor Rn and the resistor Rc. Therefore, by adjusting the values of the resistors Rc and Rn, it is possible to adjust the phase angle difference of the high voltage pulse generated in each cycle. Here, the value obtained by adding the resistance Rn and the resistance Rc is set to about 1/3 of the discharge resistance 4 in order to reduce the influence of the discharge resistance 4. The generation start phase and the final generation phase of the high voltage pulse are determined by the breakover voltage Vb and the bias voltage Vi of the SSS5. That is, the generation start phase of the high-voltage pulse matches the breakover voltage Vb of SSS5 by setting the DC bias to zero. The final generation phase of the high voltage pulse is determined by the value obtained by adding the DC bias and the breakover voltage Vb of SSS5. Therefore, by selecting both values so that the value is the same as the maximum value Vm of the sine wave AC power supply, it is possible to generate a high voltage pulse at the position of the maximum value Vm of the sine wave AC power supply.

Hereinafter, as the sine wave of the power supply voltage shifts to the third, fourth, ..., The charge amount of the capacitor 3 increases, so that the phase of the positive high-voltage pulse is gradually delayed, and conversely the negative high-voltage pulse phase gradually proceeds, the final generation phase of the high-voltage pulses in the case of a positive high-voltage pulse, the charging voltage Vi (bias voltage) and SSS5 breakover voltage Vb and the added value of the capacitor 3 (FIG. 2 Y ₁ point ), And in the case of a negative high-voltage pulse, the value is the value obtained by subtracting the charging voltage Vi of the capacitor 3 from the breakover voltage Vb of SSS5 (point Y2 in FIG. ₂ ). That is, until the charging of the capacitor 3 is completed,
The positive high voltage pulse is generated at a position sequentially delayed for each positive cycle of the sine wave AC power supply from the generation start phase X ₁ point to the final generation phase Y ₁ point shown in FIG. The high-voltage pulse is generated at a progressively advanced position in each negative cycle of the sine wave AC power supply from point X _{2 to} point Y _{2 in} FIG.

In this way, the positive high-voltage pulse is generated at a position sequentially delayed from the X ₁ point to the Y ₁ point in each cycle, and the negative high-voltage pulse is sequentially generated from the X ₂ to the Y ₂ point in each cycle. Since it is generated at the advanced position, the generation phase of the negative high-voltage pulse is advanced from the zero cross point of the sine wave AC power supply by changing the charging voltage of the capacitor, that is, the bias voltage Vi, or the breakover voltage Vb of the SSS5. It can be set to a position slightly behind the zero cross point of the load current. As a result, even the discharge lamp 7 using the phase-advancing ballast can generate a high-voltage pulse even in a phase slightly delayed from the zero cross point of the load current, and the discharge lamp 7 can be easily and surely lit. . The height of the high voltage pulse is determined by the values of the breakover voltage Vb of SSS5, the winding ratio of the pulse transformer PT, and the fuse resistance Rf, and the width of the high voltage pulse is determined by the pulse transformer P.
It is determined by the product of the inductance of the primary winding p of T and the capacitance of the capacitor Cr. In this way, the height and width of the high-voltage pulse can be adjusted by changing the values of the resistor Rf and the capacitor Cr. Therefore, the optimum pulse for starting the discharge lamp, for example, for a discharge lamp that is easy to start when the pulse voltage is high, It is possible to supply a high-voltage pulse, and a wide pulse to a discharge lamp that is easy to start when the pulse width is wide.

Next, the value obtained by subtracting the bias voltage Vi from the maximum value Vm of the positive sine wave power supply voltage is the breakover voltage V of the SSS5.
Set so that it is less than b. FIG. 3 is a pulse generation state diagram at this time. When the AC power supply 1 is initially turned on, a positive high voltage pulse is generated at point X ₁ and a negative high voltage pulse is generated at point X _{2 in} FIG. 3, and positive and negative high voltage pulses are generated in each cycle. When the charging to No. 3 becomes stable, the value obtained by subtracting the bias voltage Vi from the maximum value Vm of the positive sine wave power supply voltage becomes equal to or lower than the breakover voltage Vb of SSS5, so that the positive high voltage pulse does not occur. That is, when a positive high-voltage pulses to the sum of the breakover voltage Vb and the bias voltage Vi of SSS5 is equal to the maximum value Vm of the sinusoidal supply voltage (FIG. 3 Y ₁ point) is a final generation phase, subsequent It does not occur in the cycle. Therefore, only the negative high voltage pulse is generated in the cycle after the positive high voltage pulse is generated at the point Y ₁ . In addition, the negative high voltage pulse is generated when the charge of the capacitor is saturated (3rd
The Y ₂ point in the figure) is the final generation phase. Therefore, while a large number of negative high voltage pulses in the same direction as the load current are generated in a phase slightly delayed from the zero cross point of the load current, the number of unnecessary positive high voltage pulses is reduced. Therefore, it is possible to minimize the adverse effect of the high-voltage pulse on the other electronic components used in the circuit.

Next, the breakover voltage Vb of SSS5 is set to a value higher than the maximum value Vm of the sine wave power supply voltage. FIG. 4 is a pulse generation state diagram at this time. Since the breakover voltage Vb of the SSS 5 is higher than the maximum value Vm of the sine wave power supply voltage when the AC power supply 1 is initially turned on, neither positive nor negative high voltage pulse is generated, but the charging amount to the capacitor 3 increases, When the sum of the charging voltage Vi of No. 3 and the negative maximum value Vm of the sine wave power supply voltage becomes higher than the breakover voltage Vb of SSS5, at that time (X in FIG. 4).
_A negative high voltage pulse is generated from ( ₂ points), and a negative high voltage pulse having a progressive phase is generated in each cycle until the time when the charging of the capacitor 3 is stabilized (Y ₂ point in FIG. 4). In this way, it is possible to generate only a negative high voltage pulse from the beginning of turning on the AC power supply 1. As a result, it is possible to prevent the adverse effect of the positive high voltage pulse on other electronic components.

By the way, in the charged capacitor 3, the discharge lamp 7 is the first
When discharged in the direction of the arrow in the figure, the electric charge of the capacitor 3 becomes zero and returns to the initial state, thus serving as the original phase-advancing ballast capacitor.

The capacitor Cp is a bypass capacitor for supplying the generated high-voltage pulse to the discharge lamp 7 without passing through the magnetic leakage transformer 2, and thereby supplies the high-voltage pulse to the discharge lamp 7 efficiently. You can Also, the timer T
R turns off the series circuit after a sufficient time required for lighting the discharge lamp 7 has elapsed. Thereby, after the discharge lamp 7 is started, the generation of the high voltage pulse can be stopped.

According to the present embodiment described above, it is possible to generate a high-voltage pulse at an arbitrary position and stop the generation of a high-voltage pulse at an arbitrary position between the breakover voltage of SSS5 and the maximum value of the sine wave AC power supply. it can.

Further, according to the present embodiment, the adjusting range of the generation position of the high voltage pulse is wide, and it is also possible to generate only the negative high voltage pulse necessary when used in combination with the phase advance type ballast.

Further, in the present embodiment, since the capacitor of the phase-advancing ballast is used to sequentially generate the high voltage pulse, it is not necessary to provide a special capacitor, the circuit becomes simple, and the device can be inexpensive. .

Further, according to the present embodiment described above, since it has the pulse transformer, not only can the stepped-up pulse voltage be generated, but by adjusting the series reactance of the secondary winding of the pulse transformer, It is possible to improve the waveform of the load current, prevent flicker of the discharge lamp, and prevent extinguishment of the metal halide lamp due to an increase in the re-ignition voltage. The pulse transformer can also be used as a flicker / disappearance choke.

It should be noted that in the above-mentioned embodiment, as the semiconductor switching element, S
Although SS is used, other semiconductor switching elements such as SCR may be used.

〔The invention's effect〕

As described above, according to the present invention, a bias voltage is applied to a sine wave AC voltage by using a capacitor of a phase-advance type ballast, and the bias voltage and the breakover voltage of the semiconductor switching element are changed to change the load current. Since a pulse in the same direction as the load current is generated at a position slightly delayed from the zero cross point, it is possible to provide a discharge lamp starter capable of easily and reliably lighting a discharge lamp using a phase-advance ballast. .

[Brief description of drawings]

FIG. 1 is a circuit diagram of a discharge lamp starting device according to an embodiment of the present invention, FIGS. 2 to 4 are pulse generation state diagrams, and FIG. 5 is a conventional discharge lamp starting device combined with a phase-advancing ballast. FIG. 6 is a pulse generation state diagram of a conventional discharge lamp starting device, and FIG. 7 is an operation waveform diagram when a phase advance type ballast is used. 1 ... AC voltage, 2 ... Magnetic leakage transformer, 3 ... Capacitor, 4 ... Discharge resistance, 5 ... Bidirectional two-terminal semiconductor switching element, 7 ... Discharge lamp, PT ... Pulse transformer, D ... Diode, Cp / Cr ... Capacitor, R
n ・ Rf ・ Rc …… Resistance, TR …… Timer

Continuation of the front page (56) Reference JP-A 63-138695 (JP, A) JP-A 53-83362 (JP, A) JP-A 53-148174 (JP, A) JP-A 50-45477 (JP , A) JP 61-151999 (JP, A) Actual opening Sho 60-177495 (JP, U) Actual opening Sho 56-51296 (JP, U) Actual opening Sho 63-9800 (JP, U) Actual opening 51-16609 (JP, Y1)

Claims (3)

[Claims] 1. A discharge lamp starting device for lighting a discharge lamp with an AC power supply in combination with a phase advance ballast having a capacitor, wherein the output of the phase advance ballast for applying an adjustable bias voltage to the AC power supply. A bias circuit provided in parallel at the end, and a pulse generation circuit including a semiconductor switching element and connected in parallel to the output end are provided,
By changing the value of the circuit element of the bias circuit, the bias voltage applied to the AC power supply is changed to generate at least one of positive and negative pulses by sequentially changing its phase for each cycle of the AC power supply. A discharge lamp starting device characterized in that 2. The discharge lamp starting device according to claim 1, wherein the pulse generating circuit includes a pulse transformer for boosting the generated pulse. 3. The bias circuit comprises a charging circuit for charging the capacitor with electric charges and a discharging circuit for discharging the electric charges with which the capacitor is charged, according to claim 1 or 2. The discharge lamp starting device according to the item.