JPS5928960B2 - Single discharge lamp lighting circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention connects in parallel a series circuit of two three-terminal switching elements 51 and 52 and a series circuit of two capacitors C1 and C2 to both ends of an AC or DC power source E. A series circuit including a high-pressure starting discharge lamp and a high-pressure generation inductance element Lo of the high-pressure generation circuit A which also serves as a current-limiting element is inserted and connected between the midpoints of the series circuit, and the two three-terminal switching elements 51, The inductance element L is provided with a main lighting circuit of a series inverter type in which 52 is alternately turned ON and OFF to induce a high voltage pulse for starting or restriking (hereinafter abbreviated as high voltage).

and high-pressure starting discharge lamp ι. This relates to a single-lamp discharge lamp lighting circuit characterized in that a switching element SWo exhibiting low impedance at least to high voltage pulses at the time of starting is connected in parallel to the series circuit of the above. FIG. 3 shows a basic example of a conventional discharge lamp lighting circuit using a series inverter for one lamp.
For each three-terminal switching element 51, 52, choke coils Li, L2, a discharge lamp common to each other's closed circuit, and capacitors Cl, C2 are used.
A closed circuit is formed with each.

Now, when the 3-terminal switching element 51 becomes conductive, an oscillatory charging current flows through the 3-terminal switching element Sh choke coil L, the discharge lamp ι, the capacitor C2, and the power supply E from the power supply E, and the capacitor C2 is charged. When this is completed, the current in the three-terminal switching element 51 tends to reverse direction, and the three-terminal switching element 51 is turned off. Next, when the three-terminal switching element 52 becomes conductive, an oscillatory charging current of the capacitor Cl flows from the power supply E through the path of the capacitor Cl, the discharge lamp ι, the choke coil L2, and the three-terminal switching element 52, and the capacitor C2 and the discharge lamp ι , Chiyora coil L2, 3-terminal switching element 52, and capacitor C2 in the path of capacitor C2.
When an oscillatory discharge current flows through the three-terminal switching element 52 and the combination of charging and discharging currents of the capacitors Cl and C2 is about to go in the opposite direction, the three-terminal switching element 52 turns off. When the 3-terminal switching element S1 becomes conductive again, the charging current of the capacitor C2 and the discharging current of the capacitor C flow as in the case described above, and the main lighting circuit current flows to the discharge lamp t, causing the discharge lamp t to become the main lighting circuit. The lighting circuit drives the lighting 1. The characteristics of such conventional circuits are that they are compact, lightweight, and can achieve high efficiency and high power factor, but on the other hand, they are suitable for high-voltage starting of sodium lamps, metal lard lamps, fluorescent lamps, and other lamps that require high voltage for starting and restriking. When the target load is a discharge lamp, such a circuit cannot sufficiently start or re-ignite the high-pressure starting discharge lamp.
Figure 9 shows the case where power supply E is an AC power supply.
Naturally, bidirectional three-terminal thyristors (TRIATs) are used as the three-terminal switching elements S, S2, and the other configurations are the same as the conventional example shown in FIG.
The operation is almost the same (only the polarity is reversed every half cycle). Furthermore, in the conventional example shown in FIG. 4, a starting or restriking circuit is added to the main lighting circuit to ensure starting or restriking of the high-pressure starting discharge lamp, and the circuit shown in FIG. In this example, one of the coils L1 and L2 of the main lighting circuit, L, is used also as a high voltage generating section for starting or re-ignition, which makes it possible to omit parts.

In this circuit, a pure switch such as a relay contact is used for the switching element SWO, and the main lighting circuit and high voltage generation circuit A
Considering the point in time when both are turned on at the same time, in the starting closed circuit, the high voltage generating circuit A starts a slight discharge with the high voltage generated in the choke coil L1, and at the same time, in the main lighting circuit, the three-terminal switching element S, When is on, the discharging current of capacitor C and the charging current of capacitor C2 flow through the switching element SWO in a very short period of time, and then 3
When the terminal switching element S1 is turned off and S2 is turned on, a combined current of the oscillatory charging current of the capacitor C1 and the discharging current of the capacitor C2 flows through the choke coils L, , L2. However, in such a circuit configuration, as described above, when the switching element SWO is on, the operation of the main lighting circuit becomes unbalanced, and for example, when the 3-terminal switching element S2 is on, the oscillation period of the main lighting circuit is This has the drawback that the period is several times the period during steady lighting of the high-pressure starting discharge lamp, and that the trigger period of the three-terminal switching elements S, , S2 must be considered for this purpose. Furthermore, the conventional example shown in FIG. 5 is an example in which a high voltage generating section L3 for starting or restriking is separately provided in series with the high pressure starting discharge lamp t, and the above-mentioned disadvantages due to unbalance are avoided. However, when the main lighting circuit is turned on with the pure switch used as the switching element SWO in the on state, the L
The charging and discharging voltage of the capacitors Cl and C2 due to the C vibration becomes extremely high, and the capacitors Cl and C2 with high withstand voltage and 3-terminal switching elements Sl and S2 are required, which increases the size and cost. It was hot.
That is, when the switching element SWO is in the on state, the high voltage generator L3 and the high voltage starting discharge lamp t are short-circuited, and the circuit when the power is turned on becomes as shown in FIG. and charge/discharge voltage V
The rising process of c, is shown in FIG. Now, by turning on the power E, the E capacitors C, , C2 each become i.
voltage sharing.

Here, when the three-terminal switching element S2 is turned on, the capacitor C and the chain coil L2 are in a series vibration system, and the voltage of the capacitor C is 1.5. , E.E.
It will be charged until.

(Capacitor C2 is 100% E machiyoku, coil L
2 and becomes -1, and the capacitors Cl and C
2 voltage is balanced at 1.5E-1-E.

) At the peak of the charging/discharging voltage of the capacitors Cl and C2, the current 1c becomes O, and the three-terminal switching elements S, , S2 are turned off. Next, when the terminal switching element S is turned on, the voltage of the capacitor C becomes -1.5E due to the vibration with the choke coil L.
Next, by turning on the three-terminal switching element S2, the power source E and the reverse charging voltage of the capacitor Cl9 are positively superimposed on the capacitor C, and the capacitor C is recharged with a larger amplitude than the previous charging half cycle. As this operation is repeated, the charging/discharging voltage of the capacitor C1 theoretically becomes infinite, but in reality, the upper limit is limited by the resistance components of the choke coils Ll and L2, and it lasts from several cycles to several tens of cycles. The charging/discharging voltage of the capacitor C1 reaches a peak value and reaches equilibrium. By the way, in this way, the capacitor Cl
, C2 becomes high (actually several times to several tens of times that of the power supply E), the withstand voltage of the three-terminal switching elements Sl, S2 and the capacitors C, , C2 must be set to a large value. There was a problem in that as the dimensions increased, the cost also increased. The present invention has been made in view of the above points, and its purpose is to be able to reliably start or re-ignite a high-pressure starting discharge lamp, to have a simple configuration, and to use a capacitor and three An object of the present invention is to provide a discharge lamp lighting circuit for an S1 lamp, which can lower the withstand voltage of a terminal switching element, and can be made smaller and lower in cost. An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a circuit diagram of an embodiment of the present invention, in which two 3
A series circuit of terminal switching elements Sl, S2 and a series circuit of two capacitors Cl, C2 are connected in parallel, and the connection point of capacitors Cl, C2 and the connection point of three-terminal switching elements S, , S2 are connected in parallel. A series circuit of a high-pressure starting discharge lamp t and an inductance element LO is inserted between them. Here, the three-terminal switching elements S, S2 are composed of thyristors, but transistors may also be used.Also, since the illustrated embodiment shows a case where the power supply E is a direct current, the three-terminal switching elements S, S2 are composed of thyristors. Although reverse-blocking three-terminal thyristors are used as Sl and S2, if the power source E is AC, it goes without saying that bidirectional three-terminal thyristors (for example, triac) may be used. Alternatively, a bidirectional three-terminal switching element may be formed by connecting a transistor in parallel to the DC output end of the diode bridge. In addition, when the power source E is AC, the direction of the human power current is reversed every half cycle, and the direction of the lamp current is also reversed, but since the lamp current is originally AC, the operation is the same as in the case of DC. Become. In this case, the peak value of the lamp current varies according to variations in the voltage of the power source E. Also, an inductance element L. is a high voltage generating element that induces a high voltage used for starting or restriking, and a current limiting element for the main lighting circuit. A high voltage is generated across the inductance element LO by the voltage of the inductance element L4. SWO is a switching element for starting or re-ignition, and is an element that has an effect of turning off at least the main lighting circuit or at the same time when the main lighting circuit is turned off, and is a switching element SWO. Inductance element L. A closed circuit is constituted by the high-pressure starting discharge lamp t and the high-pressure starting discharge lamp t. Next, the operation of the embodiment shown in FIG. 1 will be described in detail below. When starting now, the pure switch used as the switching element SWO is closed at the same time as the main lighting circuit is turned on, and the high voltage generating circuit A7! ) S operation is started and a high voltage is generated in the inductance element LO. This starting high voltage is applied to the high-pressure starting discharge lamp t via the switching element SWO, and the high-pressure starting discharge lamp t starts discharging in a closed circuit consisting of the inductance element L, the switching element SWO1, and the high-pressure starting discharge lamp t. , the high-pressure starting discharge lamp t starts a slight discharge in the closed circuit due to the voltage of the inductance element LO. This switching element S
The main lighting circuit when WO is closed is equivalent to the case where both ends of the series circuit of the inductance element LO and the high-pressure starting discharge lamp t are shorted, and the main lighting circuit is as follows: In addition, only the charging and discharging of capacitors C1 and C2 is performed via the switching element SWO, and the balance of the main lighting circuit is also well maintained. Capacitor C
It is possible to lower the withstand voltage of the 1, C2 triangle and the 3-terminal switching elements S, , S2, resulting in miniaturization and cost reduction. By the way, according to the present invention, the capacitor C,
The reason why the charge/discharge voltage of , C2 does not become high will be explained below. Now, at startup when the switching element SWO is on, is the inductance component the switching element? Since the voltage is short-circuited by 0, so-called LC vibration does not occur, and no boosting effect due to LC vibration occurs. On the other hand, during steady lighting, any of the vibration systems formed by the capacitor C, the high-pressure starting discharge lamp t-inductance element LO, and the capacitor C2-the high-pressure starting discharge lamp t-inductance element LO has a vibration damping element. The high-pressure starting discharge lamps t are inserted in series, and the presence of this vibration damping element suppresses the charging and discharging voltages of the capacitors Cl and C2 to a low level (2E to 3E). A trigram,
The high-pressure starting discharge lamp 1 has a resistance component, and this resistance component has a vibration damping effect as is well known. Next, open the switching element SWO and high voltage generation circuit A.
When the operation of the high-pressure starting discharge lamp t is stopped at the same time, since the high-pressure starting discharge lamp t is in a slight discharge state, it can be easily switched to the lighting mode in the main lighting circuit and lit reliably.
FIG. 6 is a time chart showing the same operation as above. Second
The figure shows another embodiment of the present invention, in contrast to the embodiment in Figure 1 which has a separate high-voltage generating circuit A, a high-voltage generating circuit for starting is added to the main lighting circuit. A high voltage is induced in the inductance element LO which serves both as a high voltage generating element and a current limiting element.

Now, when the main lighting circuit is inserted into the circuit shown in Figure 2 and the pure switch used as the switching element SWO is closed, the high-pressure starting discharge lamp is in an open state, and the main lighting circuit current is passed through the inductance element. 3-terminal switching element S via L4 and switching element SWO
The charging and discharging currents of capacitors Cl and C2 are constant each time 1 or S2 is turned on, and at this time, the inductance value of inductance element L4 is selected to such an extent that vibrations in the main lighting circuit can be ignored. Then, when the switching element SWO is turned on, the peak value of the photoelectric voltage of the capacitors Cl and C2Q hardly increases and ideally becomes about the power supply voltage. Therefore, the voltage generated in the inductance element L4 is boosted to the inductance element LO, and the voltage generated in the inductance element L4 is boosted to the inductance element LO.
. A pulsed high voltage is induced for starting or restriking. The high voltage induced in the inductance element LO is applied to the high-pressure starting discharge lamp t via the inductance element L4 and the switching element SWO, and the high-pressure starting discharge lamp t is connected to the inductance element LO, L4, the switching element SWO, A slight discharge is started in the starting closed circuit consisting of the high-pressure starting discharge lamp t. When this switching element SWO is turned on, the series circuit between the inductance element LO and the high-pressure starting discharge lamp t is extremely small compared to the series circuit impedance.
Impedance element L4 with slight impedance
Since most of the capacitors C and C2 are short-circuited in the main lighting circuit, charging and discharging of the capacitors C, C2 is performed via the inductance element L4 and the switching element SWO. In this case, the starting pulse voltage is also applied to the high-pressure starting discharge lamp in a well-balanced manner. As described above, in the present invention, at least a switching element that shifts to a high impedance with respect to the main lighting circuit by the operation of the main lighting circuit having one inductance element, and a high voltage generating element for starting or restriking are provided. A closed circuit is provided between the inductance element of the main lighting circuit, which also serves as the main lighting circuit, and the high-pressure starting discharge lamp, making it easy to start and restart when the load is a high-pressure starting discharge lamp that requires high voltage to start discharge. Furthermore, since the starting ignition discharge is performed in a closed circuit between the switching element, the high-pressure starting discharge lamp, and the inductance element, the independence of the main lighting circuit is strengthened. Accidents such as high voltage being applied to the 3-terminal switching elements causing two of them to fire at the same time can be prevented, and the main lighting circuit can be started without changing the circuit configuration or other aspects of the main lighting circuit. The purpose is to eliminate the influence of a closed circuit, and to reduce the inductance required for the main lighting circuit configuration.
By using two inductance elements and making the inductance elements double as high voltage generating elements for starting or restriking, it is possible to omit parts and simplify the circuit, and at the same time, the main lighting at the time of starting or restriking. It is possible to prevent an imbalance between the operation of the circuit and the closed circuit for starting or re-ignition, and it is possible to take into account the trigger cycle of the 3-terminal switching element at the time of starting, and to charge the capacitor of the main lighting circuit. This provides a single discharge lamp lighting circuit that does not require consideration of extremely high voltage peak values.

Furthermore, at startup, the inductance element is short-circuited using a switching element to prevent the formation of a vibration system, which prevents the charging and discharging voltage of the capacitor from becoming high due to the boosting action of the vibration system. and the withstand voltage of the 3-terminal switch element can be lowered,
This has the effect of achieving smaller size and lower cost.

[Brief explanation of the drawing]

1 and 2 are circuit diagrams showing different embodiments of the present invention, FIG. 3 is a basic circuit diagram of a conventional example, and FIGS. 4 and 5 are circuit diagrams of different conventional examples, respectively. 6 is an explanatory diagram of the operation of the embodiment shown in FIG. 1, FIGS. 7 and 8 are explanatory diagrams of the operation of the conventional example shown in FIG. 5, and FIG. 9 is a diagram showing still another conventional example. E is a power supply, Sl and S2 are switching elements, C])
C2 is a capacitor, L is a ductance element, t is a high-pressure starting discharge lamp, and SWO is a switching element.

Claims (1)

[Claims] 1 Connect two series circuits of three-terminal switching elements and two series circuits of capacitors in parallel to both ends of an AC or DC power source, and connect a high-voltage starting discharge lamp and a current-limiting element between the midpoints of both series circuits. Insert and connect the series circuit with the high voltage generation inductance element of the high voltage generation circuit that also serves as
A series inverter-type main lighting circuit is provided in which three three-terminal switching elements are alternately turned ON and OFF to induce a high voltage pulse for starting or restriking, and the inductance element and a high-pressure starting discharge lamp. 1. A discharge lamp lighting circuit for a single lamp, characterized in that a switching element exhibiting low impedance to at least high voltage pulses at the time of starting is connected in parallel to the series circuit of the above.