JPS63207093A - Discharge lamp lighter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a discharge lamp lighting device for parallel lighting using a single separately excited inverter circuit.

(Background Art) A zero lighting circuit 10, a conventional example of which is shown in FIG. 5, includes a rectifying and smoothing circuit that rectifies and smoothes an alternating current power supply AC and converts it into a direct current voltage, and an inverter circuit that converts this direct current voltage into a high frequency voltage. Discharge lamp DL+, DL2 with high frequency voltage
It lights up the light. The discharge lamps DL, DL2 are
Connected in parallel via balancer transformer BT,
On the non-power side, preheating capacitors C3 and C are respectively installed.
4 are connected in parallel. The detection circuit 11 is a discharge lamp D.
The number of L + and D L 2 installed is detected. The control circuit 12 controls the oscillation of the inverter circuit in the lighting circuit 10 according to the detection result by the detection circuit 11. In this conventional example, current transformers CT, CT are provided to detect the current flowing through each of the discharge lamps DL, DL, and the voltage induced on the secondary side of the current transformers CT+, CT2 is detects the installation status of the discharge lamp,
Control is performed according to the mounting state of the discharge lamp. Specifically, current transformer CT+, CT
If voltage is induced on both secondary sides of z, two lamps are installed, if voltage is induced only on one side, one lamp is installed, and if no voltage is induced on either side, then two lamps are installed. As in no-load state, current transformer CT
The installed state of the discharge lamp is detected by the voltage induced on the secondary side of , , CT. However, in this conventional example, current transformers CT I and CT 2 are required to detect the current flowing through the discharge lamps DLI and D Lz.
This method has disadvantages in that the detection circuit is expensive and the device is large.

FIG. 6 shows another conventional example. In this conventional example, a resistor 'I+r2 is connected in series with the discharge lamps D L, , D L. When the discharge lamps DL, DL2 are turned on, a current that is a combination of the filament current and the lamp current flows through the resistor rl+r2, and a voltage is generated across the resistor rl+r2. The detection method is the same as the previous conventional example, using two resistors 'I
If voltage is generated on both +r2, two lamps are installed. If voltage is generated on only one resistor, one lamp is installed. If voltage is not generated on either resistor, there is no installation. It is determined that the state is under load.

However, in this method, when the discharge lamps DL, DL2 are lit, a composite current of the filament current and the lamp current flows through the resistors rI and r2, resulting in a fairly large power loss due to the resistors. It has the disadvantage that it occurs.

(Object of the invention) The present invention has been made in view of the above points, and
The purpose is to provide a discharge lamp lighting device that can detect the number of discharge lamps connected in parallel with low loss, with a simple and inexpensive configuration, and can perform control according to the number of lamps. be.

(Disclosure of the Invention) To explain the illustrated embodiment of the discharge lamp lighting device according to the present invention, as shown in FIGS. In a separately excited inverter circuit, the switch element voltage ■cE
A circuit (
In order to passively control the gate circuit 2) and the switch element Q according to the number of discharge lamps, a lamp number detection circuit 5 is provided to detect the number of discharge lamps from the generation period of the switch element voltage vcE. It is what it is.

As described above, the present invention provides a discharge lamp lighting device for parallel lighting using a single-stage separately excited inverter circuit, in which a change in the number of installed discharge lamps corresponds to the switching element voltage VCE in the inverter circuit! The number of lights is detected by utilizing the fact that it appears in the waveform.

Examples of the present invention will be described below.

fire 1 craftsmanship FIG. 1 is a circuit diagram of an embodiment of the present invention.

The power supply voltage of the alternating current power supply AC is rectified by the diode bridge DB, smoothed by the capacitor C0, and made into a direct current voltage. This DC voltage is applied to the series circuit of the primary side of the oscillation transformer OT and the switch element Q1.The DC voltage is applied to the secondary side of the oscillation transistor, which is connected to the discharge lamp D L1 through the capacitor C2 and the balancer transformer BT. DL 2 is connected, and actance elements (capacitors C, , C, ＞ are connected to the non-power side of each discharge lamp DL + and DL 2, forming a preheating circuit for the discharge lamp filament. A diode D is connected in antiparallel to the element Q.A capacitor C1 that resonates with the inductance component of the circuit is connected in parallel to both ends of the switch element Q1.The position where this capacitor CI is connected is as follows. There is no oval at both ends of the primary coil of the oscillation transformer OT.

The output of the oscillation circuit 1 is input to the control input terminal of the switch element Q through the gate circuit 2 and the drive circuit 3.The oscillation circuit 1 is connected to a general-purpose timer ICtm and its external CR element R. ,;R,,C.

The output of the 0 oscillation circuit 1 which oscillates a separately excited signal is connected to one input of the AND gate G+ in the gate circuit 2. The detection output of the element voltage detection circuit 4 is connected to the other input of the AND gate G, and the inverter ■,
The logic is inverted and input. AND gate G
1 output is the transistor T in the drive circuit 3.
It is connected to the input of a complementary emitter follower consisting of r + + T r 2. The output of the complementary emitter follower is connected to the switching element Q via a speed-up circuit consisting of a parallel circuit of resistor R6 and capacitor C6.
, is connected to the control input terminal of . In this embodiment, a bipolar transistor is used as the switch element Q1.

When the switch element Q1 is turned on by the passive on signal, current flows through the primary side of the oscillation transformer OT. When the switch element Q is turned off by the passive off signal, the oscillation transformer OT resonates with the capacitor CI due to the energy stored in the LC component of the circuit, and a resonant capacitor current flows, causing the both ends of the switch element Q1 to resonate. , a resonant voltage occurs. When this resonant voltage becomes zero, a resonant current flows through the diode D1, and when the diode current becomes zero, a separately excited signal causes a current to flow through the switch element Q as in the previous cycle. In this way, oscillation continues. This resonance causes the oscillation transformer OT to
The voltage generated on the next side is passed through the oscillating transformer OT, cage inductance and capacitor C2 to the discharge lamp D L +
, DL2 to turn it on. When one of the discharge lamps is lit, the balancer transformer BT applies a high voltage to the other discharge lamp due to the unbalance of the current flowing through each winding, thereby stably lighting both lamps. When both lights are on, the current flowing through each winding is almost the same, and the balancer transformer BT has almost no inductance component. Furthermore, when only one lamp is installed, the balancer transformer BT acts as an inductance component.

In such a single-stone separately excited inverter circuit, when there is no load, the secondary current of the oscillation transformer OT stops flowing, so its primary inductance increases, and therefore the capacitor C1 and the primary side of the oscillation transformer OT The oscillation period determined by the inductance seen from the switch element Q becomes longer, and the width of the voltage cE across the switch element Q becomes wider. In this way, even when the natural oscillation period of the circuit becomes long when there is no load, in a separately excited inverter circuit, the switching element Q turns on according to the period of the separately excited signal, so the voltage across the switching element Q, In other words, the switching element Q1 is turned on when the voltage of the resonant capacitor CI is high, and the rush current from the capacitor C1 flows into the switching element Q, causing a large power loss and causing damage to the switching element Q1. It may occur.

Therefore, the circuit shown in FIG. 1 is provided with an element voltage detection circuit 4 that detects the voltage across the switching element Q1, and when the voltage across the switching element Q is high, the gate circuit 2 prevents the passage of the passive ON signal. blocking, switch element Q1
conduction is prohibited. Therefore, even if the width of the voltage vcE across the switching element Q1 becomes longer than the period of the passive off signal of the oscillation circuit 1 in the no-load state, the drive signal is prohibited during the period of VCE>O, and the switch It is possible to prohibit conduction of element Q1.

By providing such a gate circuit 2, it is possible to safely and stably oscillate even when there is no load.

As the element voltage detection circuit 4, a voltage dividing circuit including resistors R, , R2 is used. A Zener diode ZD for regulating the output of the element voltage detection circuit 4 is connected in parallel to the resistor R2. The logic of the detection output of the element voltage detection circuit 4 is inverted by the inverter I, and the logic of the detection output is inverted by the inverter I.
It is connected to the. q of D flip-flop F F +
The output is connected to its data input. The output of the oscillation circuit 1 is connected to the clock input T of the D flip-flop FF. Q of D flip-flop FF
The output is connected to the data output of the D flip-flop FF. q output of D flip-flop FF,
The Q output of the D flip-flop FF2 is input to the discrimination circuit 6. Note that the control unit power supply voltage Vcc is obtained by a capacitor C5 connected to a smoothing capacitor C0 via a resistor R6.

FIG. 2 is an operational waveform diagram of this embodiment. The operation of this embodiment will be described below with reference to the same figure. first,
The waveform of the element voltage VcE (Fig. 2 (a)) when two lamps are installed is set to fall within the “°Low” level period of the separately excited signal (Fig. 2 (b)). When one lamp is installed, the secondary current of the oscillation transformer ○T decreases, so the inductance seen from the primary side of the oscillation transformer ○T increases, and in the wave layer of the element voltage ■cE determined by this inductance and the resonant capacitor C1. The waveform spreads and becomes longer than the "Low" level period of the passive signal. In addition, when there is no load, the inductance on the primary side of the Q-oscillating transformer OT resonates, so the waveform of the element voltage
longer than the cycle.

In this embodiment, such an element voltage V. Changes in the waveform of E are detected. As shown in Figure 2, when one lamp is installed and when there is no load, the element voltage is ■. The middle of the H waveform expands and exceeds the I Low 1 level period of the separately excited signal. This is detected by the D flip-flop FF, and the waveform shown in FIG. 2 (c) is obtained as the Q output. By delaying this Q output by the D flip-flop FF2 until the falling timing of the separately excited signal, the waveform of the element voltage゛)Ii
A signal output is obtained when there is one pulse period or more at the "gh" level.

In this way, from the change in the waveform of the element voltage V, the Q output of the D flip-flops FF, FF2 changes as shown in Table 1. By inputting this to the discrimination circuit 6, it is possible to can be determined.

In the embodiment shown in Table 1 and FIG.
The control after detecting the installation status of L, DL2 is not specified, but for example, when there is no load, the oscillation of the inverter circuit is stopped, and when one lamp and two lamps are installed, the rated lighting can be achieved. It is conceivable to perform control such as changing the oscillation frequency of the inverter circuit.

X Nitan” engineering FIG. 3 is a circuit diagram of another embodiment of the present invention.

Depending on the design of the balancer transformer BT and oscillation transformer OT, the waveform of the element voltage VclE during no-load may not exceed one pulse period of the "High" level of the passive signal. The output of circuit 2 is V
At the time of CE-○, two pulses are output as shown in Fig. 4, but the first signal has a short period, and at that time, the forward current of the diode DI of the inverter circuit is flowing, so the switch element Even if the base current is supplied to Q1, the switching element Q does not become conductive, and the switching element Q becomes conductive during the second signal period. Such an element voltage VC! 2
Taking advantage of the relationship between the signal and the passive signal, the D flip-flop FF3 is used as a T flip-flop by connecting its D input and q output, and the element voltage V is applied to its reset input R. When the E detection signal is input, the Q output becomes "High" when two lamps are installed and when there is no load, as shown in Figure 4 (D).
+” level.

Also, the element voltage V is determined by the AND gate G2. By taking the AND of the detection signal of E and the separately excited ON signal, as shown in Fig. 4 (e), when one lamp is installed and when there is no load,
The output of AND gate G2 becomes "LIig1+" level. Therefore, as shown in Table 2, the element voltage vc
D flip-flop FF3 that changes according to the waveform of ε
The discharge lamp DL is determined by the Q output of and the output of AND gate G2.
, , it is possible to determine the mounting state of DL2.

Table 2 (Effects of the Invention) As described above, the present invention provides a discharge lamp lighting device for parallel lighting using a single pond-excited inverter, which is provided with a circuit that prohibits conduction of the switch element when a switch element voltage is generated. At the same time, since the installed state of the discharge lamp is detected from the generation period of the element voltage, the structure can be simpler and cheaper than the conventional example using a current transformer, and the element voltage can be detected using a voltage detection resistor. , a high resistance can be used, and therefore the number of lamps can be detected with lower loss than in the conventional example using a current detection resistor.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of one embodiment of the present invention, Fig. 2 is an operation waveform diagram of the same as above, Fig. 3 is a circuit diagram of another embodiment of the present invention, and Fig. 4 is a circuit diagram of an embodiment of the present invention.
The figure is the same operating waveform diagram as above, Figure 5 is the circuit diagram of the conventional example, and Figure 6 is the circuit diagram of the conventional example.
The figure is a circuit diagram of another conventional example. 1 is an oscillation circuit, 2 is a gate circuit, 4 is an element voltage detection circuit, 5 is a lamp number detection circuit, DL, DL2 are discharge lamps, and Ql is a switch element.

Claims (1)

[Claims] (1) In a single-stone separately excited inverter circuit that lights multiple discharge lamps in parallel, there is a circuit that prohibits conduction of the switch element when a switch element voltage is generated, and a separately excited control of the switch element according to the number of discharge lamps. 1. A discharge lamp lighting device comprising: a lamp number detection circuit for detecting the number of discharge lamps from the generation period of the switch element voltage.