JPS6151397B2 - - Google Patents

Description

Detailed Description of the Invention The present invention connects a discharge lamp to a power source via a ballast, and connects a high-voltage pulse generating circuit for starting, a thyristor for preheating, and a discharge lamp between both filament terminals on the non-power side of the discharge lamp. A voltage dividing and smoothing circuit for the voltage waveform across both ends of the lamp is installed in parallel, and the divided voltage is detected to conduct the preheating thyristor when the discharge lamp is not lit, and to cut off the preheating energizing thyristor when the discharge lamp is lit. In a discharge lamp starting device having a control circuit, a switch element and a
A series circuit of a time-limiting capacitor and a resistor is provided, and when the terminal voltage of the time-limiting capacitor reaches a certain voltage or higher, the switch element is made conductive and the divided voltage of the voltage dividing smoothing circuit is lowered. This relates to a discharge lamp starting device that is characterized by continuing to cut off the preheating energizing thyristor after a certain period of time has elapsed, and the discharge lamp starting circuit continues to operate and the preheating current is reduced in the event of an abnormality such as lamp emission loss or deterioration of the vacuum level. The purpose of this is to prevent smoke and damage caused by temperature rises in the flow, starting circuit components, ballast, etc., as well as to prevent unnecessary power consumption.

The conventional discharge lamp starting device uses power supply 1 as shown in Figure 6.
The discharge lamp 3 is connected through the ballast 2, and the starting high-voltage pulse generation circuit 5, the preheating energization thyristor 6, and the preheating control circuit 8 are connected between both filament terminals on the non-preheating side, and the discharge lamp starts. At this time, a preheating current is applied while a high voltage pulse is applied to cause the discharge lamp to switch to lighting, and while the discharge lamp is lit, a drop in the voltage between both filaments of the discharge lamp is detected and the pulse generation is stopped, and the preheating control circuit 8 This cuts off the preheating current. In this case, due to the lifespan of the discharge lamp 2, if the filaments 4, 4' become emiless or the vacuum inside the tube increases abnormally due to breakage of the glass of the discharge lamp 3, etc., the discharge lamp 3 When the normal lighting becomes impossible, the starter continues to flow the preheating current.

In this case, the components such as the preheating switch element of the starter and the ballast continue to flow abnormal current, causing their temperature to rise, causing smoke, deterioration, etc., and causing the starter to lose its operation. It also has drawbacks such as a large power loss and a large size due to the addition of heat dissipation fins to prevent temperature rise.

The present invention is intended to eliminate such drawbacks, and will be explained in detail below with reference to Examples. In Figure 1, 1
is a commercial frequency power supply, and a filament 4,
4' is connected to one end of the fluorescent discharge lamp 3 and the other end of the filament 4, 4' is connected to generate a high voltage pulse between the filaments 4, 4' during the negative half cycle of the power source 1. , such as a three-terminal thyristor in the forward direction during the negative half cycle.
Cathode of terminal switch element 13 and capacitor 1
4 are connected in series, a resistor 15 is connected in parallel with the capacitor 14, a resistor 16 is connected between the other end of the capacitor 14 and the gate terminal of the three-terminal switch element 13, and the anode and cathode of the three-terminal switch element A high voltage pulse generating circuit 5 for starting is connected with a resistor 17 between the two terminals.

Furthermore, a series circuit of a preheating energizing thyristor 6 and a diode 18 is connected in parallel with the pulse generating circuit 5 in a forward direction during the positive half cycle period.
Furthermore, a series circuit of a diode 19, a resistor 20, and a resistor 21 is connected in parallel with the pulse generating circuit 5 in the forward direction in the negative half cycle, and a capacitor 22 is inserted in parallel with the resistor 21. Insert the constructed partial voltage smoothing circuit 7. Further, a series circuit of the base and emitter of a transistor 23 and a reference voltage element 24 such as a constant voltage diode is connected to both ends of the resistor 21, and a common terminal e is connected to the collector of the transistor 23 and the cathode of the preheating thyristor 6. A series circuit of a capacitor 25 and a diode 26 is connected between them, a resistor 27 is inserted between the collector terminal of the transistor 23 and the common terminal e, and the diode 26 side terminal of the capacitor 25 is connected to the collector terminal of the transistor 28 and the transistor 29. Connect the base terminal and the resistor 30, and connect the terminal of the filament 4 of the discharge lamp 3 and the resistor 30.
In between, a diode 31 is connected in the forward direction in the positive half cycle, both emitter terminals of the transistor 28 and transistor 29 are connected to a common terminal e, and the collector terminal of the transistor 29 is connected to a resistor 32.
A preheating control circuit 18 configured by connecting to the anode of the preheating energizing thyristor 6 via
is inserted, and the output terminal from the collector of the transistor 29 is connected to the gate terminal of the preheating energizing thyristor 6.

In the above circuit, capacitor 1 is connected in parallel with resistor 21.
A series circuit of 0 and a resistor 11 is connected to the common terminal e side, and the emitter and collector terminals of the transistor 9 are connected in parallel to the common terminal side, and the resistor 11 and the capacitor 10 are connected in parallel.
The transistor 9 is connected to the transistor 9 from the connection point of
A preheat cutoff circuit 35 is added connected to the base of.

Figure 2 shows the voltage and current waveforms of each part in Figure 1, where A is the voltage waveform of the power source 1, B is the waveform across both filaments 4 and 4' of the discharge lamp 3, C is the starting circuit current, and D is the resistor 21. This is the divided voltage waveform at both ends of .

Now, when the power switch 12 is closed, the capacitor 1 of the pulse generation circuit 5 is connected to the negative half cycle of the power supply 1.
The voltage across the terminal 4 is 0 because it is discharged by the resistor 15, and the 3-end switch element 13 is in a cutoff state. When the preheating current flowing through the preheating energizing circuit becomes 0 at time _t4 , the preheating energizing thyristor 6 is cut off and a negative voltage is applied from the power supply to both ends of the discharge lamp 3, which is divided by the resistors 16 and 17. By carefully selecting the partial pressure ratio, 3
A gate current flows between the gate and cathode of the terminal switch element 13, and the three-terminal switch element 13 is turned on, and conduction is established between the anode and cathode of the three-terminal switch element 13, and the current flows from the power supply 1 to the ballast 2 to both filaments 4 and 4' of the discharge lamp. , a current flows to the capacitor 14 through the 3-terminal switch element 13, and the capacitor 1
The four-terminal voltage increases in the direction in which the cathode side of the three-terminal switch element 13 becomes positive.

As the terminal voltage of the capacitor 14 rises, a current flows in the opposite direction from the capacitor 14 to the gate of the 3-terminal switch element through a closed circuit passing through the cathode, gate, and resistor 16 of the 3-terminal switch element 13, and increases. . At the time when the ratio of the current flowing from the anode to the cathode of the three-terminal switch element 13 to the reverse current flowing to the gate becomes a constant value (that is, t3 in Fig. ₂ ), the three-terminal switch element 13 shuts off and becomes stable. Due to the inductance of device 2, the
A high voltage pulse voltage as shown by Vp is generated.

Immediately after closing the power switch 12,
Since the temperature of both filament terminals 4 and 4' of the discharge lamp 3 is low, the discharge lamp 3 does not light up, and the discharge lamp remains active until the power supply voltage waveform shifts from the negative half cycle to the positive half cycle at time _t4 . The voltage waveform at both ends of No. 3 also has a waveform as shown in FIG. 2B.

The above-mentioned waveform at both ends of the discharge lamp is divided by a diode 19, a resistor 20, and a resistor 21, and is smoothed by a capacitor 22 connected in parallel between both ends of the resistor 21. When the discharge lamp is not lit, the waveform shown in FIG. A charging/discharging voltage waveform is generated as shown by the solid line.

A circuit constituted by a transistor 23 and a reference voltage element 24 such as a Zener diode is a circuit that performs comparison with a reference voltage, and when the discharge lamp is not lit, the voltage across the resistor 21 is higher than the voltage determined by the reference voltage element 24, and the Zener A current flows between the base and emitter of the transistor 23 through the element,
Transistor 23 is conductive, and current flows through diode 26, capacitor 25, and transistor 23, and capacitor 25 is charged to the polarity shown.

As time passes and the power supply voltage waveform shifts from negative to positive half cycle after time _t4 , a positive voltage is applied to the collector of transistor 28 through diode 31. At this time, the charge stored in the capacitor 25 is discharged between the base and emitter of the transistor 28 and through the closed loop of the resistor 27, so that the transistor 28 becomes conductive and the diode 3
1. The voltage flows between the collector and emitter of the transistor 28 through the resistor 30, the voltage between the collector and emitter decreases, and the transistor 29 becomes cut off.

Therefore, due to the positive voltage applied between the anode and cathode of the thyristor 6 for preheating energization via the diode 18, a trigger gate current flows through the resistor 32, the gate, and the cathode of the thyristor 6 for preheating energization, and at time _t5 . The preheating energizing thyristor 6 becomes conductive, and the preheating current flows from the power source 1 through the regulator 2, the filament terminals 4, 4' of the discharge lamp 3, the diode 18, and the preheating energizing thyristor 6 as shown in FIG. It flows like that. This preheating current continues even after the power supply voltage waveform passes the positive peak value and decreases and transitions from a positive half cycle to a negative half cycle at time _t6 .
The current continues to flow due to the inductance of , and becomes 0 at time _t7 , and the preheating energizing thyristor 6 shuts off.

By repeating the above operations, the filament terminals 4, 4' of the discharge lamp 3 are preheated in the positive half cycle and their temperature rises, and a high voltage pulse is generated in the negative half cycle as the preheating progresses. The lamp enters the lighting state, and in the negative half cycle, the lamp lighting waveform becomes as shown by the broken line in FIG. 2B, and its peak value becomes small.

When this state is reached, the voltage of the voltage dividing smoothing circuit 7 decreases as shown by the broken line in FIG. 25 is no longer charged, and the capacitor 25
When the charge is discharged, the transistor 28 becomes cut off in the positive half cycle, current flows between the base and emitter of the transistor 29 through the diode 31 and the resistor 30, and the transistor 29 becomes conductive.
Current flows between the collector and emitter of the transistor 29 through the resistor 32, and the voltage between the collector and emitter of the transistor 29 decreases, and the gate current of the preheating energizing thyristor 6 stops flowing, and the preheating energizing thyristor 6 is cut off and discharged. The electric light 3 is also lit in the forward direction, and is completely lit.

The above is a description of the case where the discharge lamp 3 is normal, but if the discharge lamp 3 becomes emissive due to its lifespan, or some abnormal condition occurs such as the pressure inside the tube increases due to damage to the discharge lamp tube, etc. Let's talk about the case.

When the power switch 12 is closed, the voltage shown by the solid line in FIG. be done. If the discharge lamp 3 does not light up, the voltage across the capacitor 10 reaches or exceeds the reference voltage of the constant voltage element after a certain time T determined by the charging time constant determined by the capacitance value of the resistor 11 and the capacitor 10, the voltage of the constant voltage element 34, etc. Then, the base current of the transistor 9 flows, and a current flows between the emitter and collector of the transistor 9, lowering the combined resistance across the resistor 21, and the voltage across the resistor 21 becomes equal to the voltage between both filaments of the discharge lamp 3. The base current of the transistor 23 stops flowing even though it is high, and the base current of the transistor 23 stops flowing as it falls below the reference voltage of the reference voltage element 24, and in the same manner as described above, the preheating energizing thyristor 6 is cut off and the preheating current is stopped. Prevents temperature rise in the ballast and starter circuits.

In the circuit shown in FIG. 1, after the power switch 12 is turned on, the preheat cutoff circuit 35 operates, and as a result, the preheating energizing thyristor 6 is cut off, and the capacitor for limiting the preheating cutoff time required until the preheating current stops. By adjusting the capacitance of 10 and the value of resistor 11 to set the time longer than the time required for normal lamp lighting, the transistor 23 is cut off first when the lamp starts normally, and normal lighting is not affected at all.

FIG. 3 shows another embodiment of the present invention, in which a tension oscillation circuit is used as the pulse generation circuit 5 using a two-terminal thyristor 36 such as S, S, S, etc., a capacitor 37, and a pulse transformer 38. A PNP transistor is used as the switch element, the positions of the time-limiting capacitor 10 and the resistor 11 are reversed, and a two-terminal thyristor 39 is used as the voltage detecting element at both terminals of the voltage dividing smoothing circuit 7, as shown in FIG. It is possible to perform exactly the same operation as in the embodiment.

4 shows another embodiment of the preheat cutoff circuit 35 shown in FIG. 1, in which a three-terminal thyristor 42
Create a parallel circuit consisting of a series circuit of the anode and resistor 43, a series circuit of time-limiting capacitor 10, and resistor 11, and connect the three terminals from the connection point of capacitor 10 and resistor 11 through the series circuit of resistor 44 and constant voltage element 45. It is connected to the gate and terminal of the thyristor 42, and when the voltage across the capacitor 10 exceeds a certain level, the thyristor 42 turns on, lowering the combined resistance across the resistor 21 and cutting off the preheating current, as shown in FIG. A similar effect can be obtained.

Furthermore, in FIG. 5, a capacitor 46 is used in place of the gate trigger resistor 17 of the starting high-voltage pulse generation circuit 5 shown in FIG. When the power supply voltage waveform appears between both terminals of the discharge lamp, the voltage changes.
Due to the small dv/dt, the gate trigger current decreases, and the pulse generation element is cut off, stopping pulse generation. At the same time, communication problems caused by noise generated in the air or through the power line can be eliminated. It is something. Further, the present invention can be similarly applied to a multi-lamp lighting circuit, and similar effects can be obtained.

As described above, the present invention provides a series circuit of a switch element, a time-limiting capacitor, and a resistor in parallel with a voltage dividing and smoothing circuit, and makes the switch element conductive when the terminal voltage of the time-limiting capacitor reaches a certain voltage or higher. By lowering the partial voltage of the partial voltage smoothing circuit, the preheating energizing thyristor continues to be cut off after a certain period of time after the power switch is turned on. Preheating current continues to flow through the discharge lamp circuit due to an abnormality such as an abnormal temperature rise, which prevents abnormal temperature rises and smoke generation in the ballast and starting circuit components, and eliminates unnecessary power consumption. Even though the discharge lamp produces a slight discharge using high-pressure pulses when starting up when the temperature drops,
Even if the voltage between both filament terminals does not drop to the lighting state due to insufficient pulse energy and the preheating energizing thyristor conducts and the discharge lamp does not light up, the discharge lamp can be turned on by preheating being cut off after a certain period of time after switching on. It is possible to shift the light to normal lighting. In other words, preheating the discharge lamp lowers the discharge starting voltage of the discharge lamp, but since this is based on an increase in the temperature of the filament, there is little point in continuing it for more than a certain period of time. Even if preheating is stopped after a certain period of time has elapsed, the discharge starting voltage will remain low for a while due to the thermal time constant. Therefore, as in the present invention, when the discharge lamp is not lit, It is better to stop preheating after the lapse of time and increase the voltage applied to the discharge lamp to facilitate starting of the discharge lamp. When the present invention is applied to a multi-lamp circuit, all the normal lamps other than the abnormal lamp can be turned on, and the practical value is increased.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of an embodiment of the discharge lamp starting device of the present invention, Fig. 2 is a voltage and current waveform diagram of the main parts of the same as above, and Fig. 3
The figure is a circuit diagram of another embodiment of the present invention, FIG. 4 is a circuit diagram of another embodiment of the preheating cutoff circuit of the present invention, and FIG. 5 is a circuit diagram of another embodiment of the high voltage pulse generation circuit for starting of the present invention. FIG. 6 is a circuit diagram of a conventional discharge lamp starting device. 1... Power supply, 2... Ballast, 3... Discharge lamp, 4
...Filament, 4'...Filament, 5...
...High-voltage pulse generating circuit for starting, 6...Thyristor for preheating energization, 7...Voltage division smoothing circuit, 8...Preheating control circuit, 9...Switch element, 10...Capacitor for time limit, 11...Resistor, 12 ...Power switch.

Claims (1)

[Claims] 1. A discharge lamp is connected to the power supply via a ballast, and a high-voltage pulse generation circuit for starting, a thyristor for preheating, and a voltage division smoothing circuit for the voltage waveform across the discharge lamp are connected between both filament terminals on the non-power supply side of the discharge lamp. A discharge lamp starting device having a preheating control circuit that detects the partial voltage, conducts the preheating energizing thyristor when the discharge lamp is not lit, and cuts off the preheating energizing thyristor when the discharge lamp is lit, A series circuit of a switch element, a time-limiting capacitor, and a resistor is provided in parallel with the voltage-dividing smoothing circuit, and when the terminal voltage of the time-limiting capacitor reaches a certain voltage or higher, the switching element is made conductive, and the voltage dividing circuit of the voltage-dividing smoothing circuit is A discharge lamp starting device characterized in that a preheating energizing thyristor continues to be cut off after a certain period of time has elapsed after turning on a power switch by lowering the voltage.