JPS5913839B2 - discharge lamp lighting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a discharge lamp lighting device, and provides a device that is small, lightweight, and has excellent electrical characteristics.

FIG. 1 shows a discharge lamp lighting device on which the present invention is based, in which a current limiting element consisting of an inductance element 2 and a capacitor 3 connected in series and a series circuit of a discharge lamp 4 are connected to both ends of an AC power source 1. In addition, a triac 5 is connected in parallel with the discharge lamp 4, and a relaxation oscillation type trigger pulse consisting of a current limiting resistor 6, a constant voltage diac T, a charging resistor 8, a charging/discharging capacitor 9, and a switching diac 10 is connected. The generating circuit 11 has its power supply terminals connected to both ends of the AC power supply 1 and its output terminal connected to the control terminal of the triac 5.

In such a circuit, when the discharge lamp 4 has been started and lit by, for example, an unillustrated starting means and is kept lit, a pulse is generated at a constant phase tl in each half cycle of the power supply voltage V with the illustrated polarity as shown in FIG. 2A. As shown in the circuit 511, the pulse voltage V
p is generated and applied to the control end of the triax 5, and the triax 5 becomes conductive as shown in c.

When the triax 5 is ignited and conducts, a lightning current 15 such as 102 flows from the AC power supply 1 through the inductance element 2, the capacitor 3, and the triax 5 in the conductive state, and the capacitor 3 has a strong vibration effect only with the inductance element 2. Therefore, it is efficiently charged to the polarity shown in the figure, and exhibits a high terminal voltage Vc as shown by the accumulation of charge. Next, when the current 1| flowing through the triac 5 due to the oscillating action of the inductance element 2 and the capacitor 3 enters the next half cycle of the power supply voltage V, and attempts to reverse its polarity at phase f2, the triac 5 conducts its conduction. The capacitor 203 is no longer held and returns to a non-conductive state, and the charge accumulated in the capacitor 3 is not released (the terminal voltage Vc of the capacitor 203 is temporarily held as it is). At this phase f2, capacitor 3
The terminal voltage Vc of is added to the power supply voltage V, and the voltage at the terminals of the capacitor 3 is 25Vc.
The AC power supply 1 immediately re-ignites due to the dominant high voltage.
A lamp current 14 as shown in (F) is supplied by the electric power from V and the charge stored in the capacitor 3, and a lamp voltage V4 as shown in (G) is generated. During this period, the terminal voltage Vc of the capacitor 3 becomes smaller as the accumulated charge is released, and finally its polarity is reversed and the capacitor 3 is charged. Then, a pulse voltage Vp is generated at phase f, and when the triax 5 becomes conductive again, both ends of the discharge lamp 4 are short-circuited and the discharge ignition is stopped, and at the same time, a circuit 35 containing only the inductance T and the capacitor 3 is formed. The capacitor 3 is charged even more rapidly due to the strong vibrational action with the inductance element 2, and its electronic voltage V
Increase c and prepare the phase for the arrival of 2. Thus, during each half cycle of the supply voltage V, the triac 5 opens and closes,
In the on period, a strong vibration condition is obtained including the capacitor 3, and the next charge is accumulated in the capacitor 3, and a high voltage is obtained between its terminals. The voltage is the power supply voltage V,
By adding the charge to the discharge lamp 4, it is very easy to re-ignite the lamp, and at the same time, the charge stored in the capacitor 3 is combined with the power from the power supply 1 to supply the discharge lamp 4 to obtain a steady lamp current 14. is completed, and the discharge lamp 4 maintains normal lighting. Note that H indicates the input current 11 of the entire circuit, and a continuous waveform without any pause sections can be obtained. The discharge lamp lighting device which is the basis of the present invention is constructed as described above, and opens and closes a thyristor such as a triax, which is substantially in parallel with the discharge lamp, during each half cycle of the power supply voltage, so that the thyristor element is in the closed state. Sufficient charge is accumulated in the capacitor of the strong oscillation circuit formed in
The high terminal voltage is applied to the discharge lamp before it is re-ignited to easily and reliably re-ignite it, and the accumulated charge is supplied as a lamp current along with the power from the power supply to form a sufficient current. Therefore, normal lighting of the discharge lamp can be maintained at a lighting tube voltage where the power supply voltage is lower than the restriking lightning voltage required for restriking the discharge lamp. Since there is almost no difference in , the current limiting element including the capacitor can be made sufficiently smaller than the conventional one, which has the effect of making the device more compact and reducing electrical loss.

Here, the impedance of a discharge lamp such as a fluorescent lamp is mostly a resistance component, and this impedance z reaches its maximum near normal temperature of 20 to 25 degrees Celsius, as shown in Figure 3, and when the ambient temperature T is It tends to decrease as the temperature gets higher or lower.

The circuit on which the present invention is based uses the energy stored in the capacitor 3, which is a current limiting element, in a strong oscillating circuit formed when a thyristor such as a triax 5 is closed, and the resistance component of the discharge lamp 4 when the thyristor opens. The basic idea is to obtain a lamp current by discharging it into a weak oscillating circuit formed by the thyristor, but when the ambient temperature T decreases or increases and the internal impedance of the discharge lamp 4 decreases, the thyristor opens. Even when the thyristor is in the non-conducting state, a strong oscillating circuit is formed, and as shown in FIG. Furthermore, the internal impedance of the discharge lamp 4 is small.
Then, as shown in the figure, the current 1 progresses further and passes through the zero point at a phase slightly ahead of the phase t1.In this state, when the pulse voltage Vp is applied at the phase t1, the thyristor stops conducting from this point. The phase t of the first next half cycle
Since conduction is maintained up to around 1, the thyristor closes over almost the entire range of the power supply voltage 1, and the discharge lamp 4
The section where power is supplied to the discharge lamp 4 is extremely short.
It had the disadvantage that it would flicker or disappear, causing it to operate abnormally. In order to eliminate such shortcomings,
There are methods such as advancing the firing phase t1 of the thyristor in advance, or increasing the inductance element 2 and capacitor 3 components to such an extent that the influence of the change in internal impedance of the discharge lamp 4 can be ignored. However, in the former case, the power factor deteriorates, and in the latter case, a new disadvantage arises in that the size of the device is unavoidable.

The present invention has been made in view of these points, and an object of the present invention is to efficiently eliminate the above-mentioned drawbacks and inconveniences all at once.

The present invention connects a current-limiting element including a capacitor at both ends of an AC power source and an inductance element to a series circuit of a discharge lamp, connects a thyristor in parallel with the discharge lamp, and synchronizes with the power source during each half cycle of the power source voltage. A control circuit that gives a trigger pulse to the thyristor once is provided, and the trigger pulse generation phase T of the control circuit is delayed most at around room temperature and advances as it goes from around room temperature to a low temperature or high temperature region, as shown in Figure 5. It is characterized by being made to be able to

FIG. 6 shows a specific embodiment according to the present invention, in which the discharge lamp 4 in FIG. 1 is a fluorescent lamp, a triax 5 is connected between the non-power supply side terminals of the filament of the fluorescent lamp 4, and a trigger pulse generating circuit is provided. 11 is connected to an AC power source through one filament of the fluorescent lamp 4, and in addition, in place of the charging resistor 8, a negative characteristic heat sensitive element 12 and a positive characteristic heat sensitive element 1 are connected.
It consists of three parallel paths.

In such a device, the negative characteristic heat-sensitive element 12 has a resistance value R that decreases as the ambient temperature T increases, as shown in FIG.
As shown in FIG. 8, the positive characteristic heat-sensitive element 13 has a property of increasing the resistance value R as the ambient temperature T becomes higher, and its combined resistance R is highest near normal temperature as shown in FIG. The charging speed of the charging/discharging capacitor 9 of the trigger pulse generation circuit 11 is slowest near room temperature, and therefore the pulse generation phase t1 is delayed, and as the temperature moves away from room temperature, the charging speed becomes faster and the pulse generation phase T, advances, thereby obtaining the desired characteristics as shown in FIG.

In this way, by obtaining the temperature characteristics of the pulse generation phase as shown in Fig. 5, the trigger pulse generation phase t1 of the thyristor follows the phase of the current 1, which advances as the temperature changes.
As a result, the termination of the current 11 advances beyond the trigger pulse generation phase T, and an abnormal operation in which the thyristor becomes conductive for nearly the entire half cycle can be effectively prevented. Note that the method for obtaining the ambient temperature vs. trigger pulse generation phase characteristics as shown in FIG. 5 is not limited to the embodiment shown in FIG. Alternatively, a charging/discharging capacitor, a constant voltage element, etc. in the trigger pulse generating circuit may be subjected to a temperature-sensitive change.

The discharge lamp lighting device according to the present invention is configured as described above, and as the impedance of the discharge lamp decreases due to temperature and the current advances, the generation phase of the trigger pulse for the thyristor is advanced, so that the occurrence of a thyristor trigger pulse is detected. It prevents operation, not only at room temperature but also under any ambient temperature.
This has the effect of making it possible to obtain desired electrical characteristics.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a discharge lamp lighting device on which the present invention is based;
Fig. 2 shows the waveforms of each part, Fig. 3 shows the temperature characteristics of the discharge lamp, Fig. 4 shows the waveforms for explanation, Fig. 5 shows the temperature characteristics of the trigger pulse required for the present invention, and Fig. 6 shows the temperature characteristics of the discharge lamp. The figure is a circuit diagram of a specific embodiment according to the present invention, and FIGS. 7 to 9 are characteristic diagrams of parts used in the above embodiment.

Claims (1)

[Claims] 1 Connect a series circuit of a discharge lamp and a current-limiting element including a capacitor and an inductance element to both ends of an AC power supply, connect a thyristor in parallel with the discharge lamp, and synchronize with the power supply so that the power supply voltage remains constant during each half cycle. The present invention is characterized in that a control circuit is provided to give a trigger pulse to the rotation thyristor, and the trigger pulse generation phase of the control circuit is most delayed near normal temperature and advances as it goes from near normal temperature to a low temperature or high temperature region. Discharge lamp lighting device.