JPS5919433B2 - lighting circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lighting circuit comprising a transistor inverter used for emergency lighting and normal lighting.

FIG. 1 shows a conventional lighting circuit of this type, in which a two-stone inverter circuit section 2 is rectified by a commercial power source 6 by a rectifying and smoothing power source means consisting of a rectifier T, a resistor R1, and a capacitor C4. However, if the discharge lamp 1 is blinked frequently by opening and closing the blinking switch SW, preheating and lighting start-up may be performed at the same time. Therefore, a high voltage is applied when the electrodes of the discharge lamp 1 are not sufficiently warmed, and the material of the active filament 3 is consumed, resulting in a shortened lifespan of the discharge lamp 1.

Therefore, as shown in Fig. 2, a delay relay 8 is provided that starts time-limited operation when the power is turned on and turns on the relay contacts after a predetermined period of time.The preheating current is passed through the filament 3 of the discharge lamp 1, and then the contacts are turned on. A circuit was also provided that applied the secondary output of the inverter circuit section 2 to the discharge lamp 1, but wear of the relay contacts became a problem, and even if a thyristor was used to make the contacts non-contact, the voltage resistance and electrical Due to the problem of insulation between the commercial power source and the load stipulated in the Act, it is necessary to use a power transformer for controlling the thyristor, which increases its size.Also, the power loss in the starting resistor generates a lot of heat, so the size of the resistor itself has to be increased. It didn't happen. The present invention has been made in view of the above-mentioned drawbacks, and an object thereof is to provide a lighting circuit that saves preheating power while taking the life of a discharge lamp into consideration. The present invention will be explained below with reference to Examples. FIG. 3 shows a circuit diagram of one embodiment. The first inverter circuit section 2 consists of a transistor inverter circuit using transistors Q5, Q6, etc., and connects both ends of the secondary winding n2 of the oscillation transformer Tl to both ends of the discharge lamp 1 via a reactance capacitor Cl. The secondary output is applied as a lighting voltage. On the other hand, the second inverter circuit section 4 is composed of a transistor inverter circuit including a transistor Q, etc., and the oscillation transformer T2 has a pair of preheating windings nH and a timer winding n as secondary windings. The preheating windings nH are respectively connected to the filament 3 of the discharge lamp 1 via current limiting capacitors C2 and Cs, and a preheating current flows through the filament 3 during operation. On the other hand, timer winding N. is for supplying power to the timer section 5 via the diode D and the smoothing capacitor C6. The timer section 5 has a timer winding N obtained by the operation of the inverter circuit section 4. The inverter circuit section 4 starts its time-limited operation from the start of operation, and outputs a control signal for operating the inverter circuit section 2 after a predetermined time Δt. Next, the operation of the lighting circuit of the present invention will be explained.

Now, if you turn on the flashing switch SW, the commercial power supply 6
is rectified by a rectifier 7, further current-limited by a resistor R1, and smoothed by a capacitor C4, and the obtained DC voltage is applied and supplied to the inverter circuit section 4 as shown in FIG. 4a. Here, the inverter circuit section 4 applies a starting current to the base of the transistor Q with the voltage divided by the resistors R2 and R3, the collector current of the transistor Q1 begins to flow, and a potential is generated in the collector winding NnC2 of the oscillation transformer T2. , a voltage is also induced in the base winding NB2 in the positive direction. When the transistor Q1 is saturated, the collector current continues to increase by a certain amount, but because the inductance of the oscillation transformer T is not ideal, the increase stops after a certain period of time, and the induced voltage in the base winding NB2 decreases, so that the collector current continues to increase by a certain amount. tries to turn off. At that time, the residual energy in the collector winding NC2 is released, and a negative voltage appears in the collector winding Nc27lC in the negative direction, and also in the base winding NB2, and the transistor Q
1 turns on quickly. Thereafter, the transistor Q1 starts to turn on due to the starting current flowing to its base, performs the first operation, and repeats the above operation to oscillate at a high frequency.
This oscillation causes the preheating winding NH and the timer winding N to
. A high frequency voltage is generated respectively. Winding N for timer. The voltage generated is rectified and smoothed by a diode D1 and a capacitor C6, and becomes a control power source for the inverter circuit 2 and a power signal for the timer section 5. The timer section 5 biases the pace of the transistor Q2 with the time constant of the resistor R4 and the capacitor C5, turns on the transistor Q2, and when its emitter voltage exceeds the Zener voltage of the Zener diode Z-D, the transistor Q3 is turned on and controlled. It has time-limiting means for issuing a signal. By setting the time constants of C5 and R4 to required values, the delay time of Δt is determined. During this time Δt, the transistor Q is off, so the inverter circuit section 2
Since the transistor Q4, which is a switch means, is in an off state, the base current to the transistor Q5 or Q6 obtained by the resistors R, R6, which are bias means connected in parallel to the timer section 5 through the transistor Q4, is as follows. Not supplied. On the other hand, what about the inverter circuit section 4? is discharge lamp 1
Since the load is light, with only the filament 3 acting as a load, a large preheating current can be applied to the filament 3 shown in FIG. 4b, and the filament 3 of the discharge lamp 1 can be heated intensively. Now, when the delay time △t has elapsed,
Since the transistor Q3 is turned on, the transistor Q4 is turned on, and the transistors Q5 and Q of the inverter circuit section 2 are turned on.
6 is supplied with base control power, the inverter circuit section 2 starts oscillating as shown in FIG. 4c, and the oscillation transformer T1
A high frequency voltage is applied to the discharge lamp 1 from the secondary winding N2 of the discharge lamp 1, and the discharge lamp 1 is started, lit, and maintained in the four sections 1fC shown in FIG. 4d. The @ section in d in the figure indicates the section where the discharge lamp 1 is turned off. At this time of starting, the filament electrode of the discharge lamp 1 will not be damaged since sufficient preheating has been performed in advance. Therefore, it is possible to prevent the life of the discharge lamp 1 from becoming extremely short due to the blinking frequency. At the same time, by supplying the base current to the transistor Q5 or Q6 of the inverter circuit section 2, the load on the inverter circuit section 1 increases, and the output of the preheating winding nl automatically decreases, as shown in Fig. 4b.
The preheating current will be reduced. Note that even if the preheating current decreases after lighting, there is no effect on the life of the discharge lamp because there is only enough preheating current for restriking. There is no need to flush too much. Since the present invention includes the first and second inverter circuit sections, the timer section, the rectifying and smoothing power supply means, the switch means, and the bias means constructed as described above, the first The switch stage does not apply a base current to the oscillation transistor of the inverter circuit, and the oscillation of the first inverter circuit is stopped, while the second inverter circuit supplies a preheating current to the filament of the discharge lamp. Moreover, when the discharge lamp is lit, the high voltage output of the second inverter circuit section is used as a bias power source for the first inverter circuit section, so the high voltage output for preheating of the second inverter circuit section is reduced. In addition, since the lighting operation is performed after a sufficient preheating current has flowed at the time of starting and lighting, consideration can be given to the life of the discharge lamp due to flickering. Since the starting base current and the operating power supply for the timer section are obtained from the high voltage output of the second inverter circuit section, the desired voltage can be easily obtained by stepping down the oscillation transformer of the second inverter circuit section. This has the effect that power loss and heat generation of the starting resistor can be reduced.

[Brief explanation of the drawing]

1 and 2 are diagrams of a conventional example, FIG. 3 is a circuit diagram of an embodiment of the present invention, and FIG. 4 is a time chart of the same as above, where 1 is a discharge lamp, 2 is an inverter circuit section, and 3 is a circuit diagram of an embodiment of the present invention. filament, 4
is a second inverter circuit section, 5 is a timer section, 7 is a rectifier, Q4. Q5 and Q6 are transistors, R5 and R6 are resistors, D1 is a diode, C4 and C6 are capacitors, and Δt is a predetermined time.

Claims (1)

[Claims] 1 A first inverter circuit unit that generates a high frequency output to be applied as a lighting voltage to a preheating discharge lamp; and a first inverter circuit unit that generates a high frequency output for preheating to be applied as a preheating voltage to the filament of the preheating discharge lamp; a second inverter circuit unit that generates a high frequency output for controlling the circuit unit; and a second inverter circuit unit that operates using a DC voltage obtained by rectifying and smoothing the high frequency output for control as a power source, and outputs a control signal after a predetermined time has elapsed from the start of operation. and a rectifying and smoothing power source means for rectifying and smoothing a commercial power source to supply power to the first and second inverter circuit sections, respectively, and the first inverter circuit section is equipped with A switch means that is turned on and a bias means to which the DC voltage is applied through the switch means and which supplies a starting base current to an oscillation transistor of the first inverter circuit section from the DC voltage. A lighting circuit featuring: