JPS61218095A - Discharge lamp lighting apparatus - 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 having a separately excited high frequency inverter circuit, and relates to a discharge lamp lighting device that can adjust the light output of a discharge lamp that is lit by pulsating current. be.

[Background technology]

Conventionally, this type of discharge lamp lighting device has been a high-frequency lighting device that combines a rectifier circuit that rectifies commercial power and a high-frequency conversion circuit (inverter), and a method using frequency changes has been proposed as a method of controlling light output. ing.

FIG. 8 shows a circuit diagram of a conventional discharge lamp lighting device.

This discharge lamp lighting device performs full-wave rectification of AC power supply AC in a rectification circuit 1, applies the rectified power supply voltage obtained from the rectification circuit 1 to a separately excited type high frequency inverter circuit 2, and from this high frequency inverter circuit 2 inductor LO, capacitor Go and a discharge lamp 5, and a starting voltage and a restriking voltage are applied to the discharge lamp 5 by the resonant voltage of the series resonant circuit of the inductor Lo and the capacitor CO.
After lighting, the lamp current limited by the inductor Lo flows through the discharge lamp 5, and the high frequency inverter circuit 2
The control circuit 3 drives and controls the .

When the switching frequency of the high-frequency inverter circuit 2 is changed by the control circuit 3, the impedance of the inductor LO changes, and thereby the discharge lamp 5 can be dimmed.

Figure 9 shows the waveform when all lights are on, (A) is the rectified power supply voltage, (
B) shows the lamp voltage, and (C) shows the lamp current.

FIG. 10 shows waveforms during dimming lighting, in which (A) shows the rectified power supply voltage, (B) shows the lamp voltage, and (C) shows the lamp current.

As can be seen from these figures, during dim lighting, the switching frequency is higher than when fully lit, the impedances of inductors t and a are higher, and the lamp current is smaller. Further, due to the change in the switching frequency, the no-load secondary voltage becomes lower than when the lamp is fully lit, and the re-ignition timing is delayed from the position α when the lamp is fully lit to the position β.

Figure 1L shows the inductor L in the circuit of Figure 8.

and shows the relationship between the resonance voltage (no-load secondary voltage) of the capacitor Go and the switching frequency.

In Fig. 11, curve A shows the resonance characteristic of the resonant circuit of inductor LO and capacitor Co, curve B shows the resonance characteristic of the resonant circuit of inductor Lo, capacitor Go, and discharge lamp 5, and X shows the resonance characteristic of the resonant circuit of inductor Lo, capacitor Go, and discharge lamp 5. Switching frequency, Y is switching frequency when dimmed lighting, ro is inductor L
O+ capacitor C.

is the resonant frequency of the resonant circuit.

The discharge lamp lighting device shown in Fig. 8 is designed to increase the impedance of the load circuit 4 by increasing the switching frequency during dimming, thereby suppressing the lamp current in the lighting state. As the switching frequency increases, the no-load secondary voltage for any given supply voltage decreases, resulting in a longer time to re-ignition in each cycle.
The discharge lamp failure time also becomes longer. For this reason, there is a drawback that the lamp power factor deteriorates as the light is dimmed compared to full lighting, and the lighting efficiency (ratio of lamp power to input power) also decreases. Another disadvantage is that when the dimming is deepened, the no-load secondary voltage does not reach the re-lighting voltage, making deep dimming impossible.

[Purpose of the invention]

This invention can increase the lamp power factor and lighting efficiency by shortening the time until re-ignition in each cycle when lighting a discharge lamp with a pulsating current, and also prevents deep country light from fading or flickering. An object of the present invention is to provide a discharge lamp lighting device that can operate stably without any problems.

[Disclosure of the invention]

The discharge lamp lighting device of the present invention includes a rectifier circuit that rectifies an AC power source, a passive high-frequency inverter circuit that is supplied with power from the rectifier circuit, a discharge lamp, and a resonant circuit. a load circuit to be powered;
After each cycle of the rectified power supply voltage applied from the rectifier circuit to the high frequency inverter circuit, the switching frequency of the high frequency inverter circuit is changed to the resonant frequency of the series resonant circuit during the first period of re-ignition of the discharge lamp. and setting the switching frequency of the high frequency inverter circuit to a first frequency apart from the series in a second period other than any first period after re-ignition of the discharge lamp of each cycle of the rectified power supply voltage. and a control circuit that sets a second frequency close to the resonant frequency of the resonant circuit, and the ratio between the first and second periods is variable.

Thus, any first period after re-ignition of the discharge lamp for each cycle of the rectified power supply voltage switches the high frequency inverter circuit at a first frequency away from the resonant frequency of the resonant circuit, and for each cycle During the second period other than the first period, the high frequency inverter circuit is operated at a second period close to the resonant frequency.
Since switching is performed at a frequency of It can be ignited and the lamp power factor and lighting efficiency can be increased.

Further, by advancing the re-ignition timing, the crest factor of the lamp current can be lowered, and as a result, the switching element current of the high frequency inverter circuit can be reduced, and its loss can be reduced. In addition, by changing the ratio of the first period of switching at the first frequency and the second period of switching at the second frequency in each cycle, dimming can be achieved by simply switching between two frequencies in each cycle. It can be performed.

Furthermore, even if the dimming is deep, switching will always be at the first frequency during the period until the re-ignition of each cycle.
The discharge lamp does not go out or flicker.

Embodiment A first embodiment of the present invention will be described with reference to FIGS. 1 to 4. As shown in Figure 1, this discharge lamp lighting device performs full-wave rectification of AC power supply AC in a rectifier circuit 1, applies the obtained rectified power supply voltage to a separately excited half-bridge type high-frequency inverter circuit 2', and converts the high-frequency The high-frequency power obtained from the inverter circuit 2' is added to the load circuit 4 consisting of the inductor Lo, the capacitor Co, and the discharge lamp 5, and the resonant voltage of the series resonant circuit of the inductor LO and the capacitor Co is applied to the discharge lamp 5 as the starting voltage and restriking. It is applied as a voltage, and after lighting, it is 1il11 with inductors t and o! It is designed to allow the lamp current to flow.

The high frequency inverter circuit 2' includes switching elements (transistors) Ql, Q2 . Diode DI.

D2 and capacitors c, c2, and the control circuit 3' controls the switching frequency and drives the switch element Ql + Q2.The control circuit 3' alternately controls the switching elements Ql and Q2 equally. The switching frequency of the high-frequency inverter circuit 2' is changed to the resonance of the resonant circuit of the inductors t, o and the capacitor Co during an arbitrary first period after the discharge lamp 5 is re-ignited in each cycle of the rectified power supply voltage. A first frequency Y' (KHz) which is distant from the frequency ro is set, and the switching frequency of the high frequency inverter circuit 2' is set to a second frequency close to the resonance frequency ro during a second period other than the first period of each cycle. The frequency is set to X'(K)Iz), and the ratio of rainy periods can be changed.

However, in order to shorten the time from the beginning of each cycle to restriking, the frequency X' of the second period including the period until restriking of each cycle of the rectified power supply voltage is, as described above, Inductor Lo and capacitor G of load circuit 4
The resonant frequency f of o.

The switching frequency Y' in the second period other than the above must be set so that the voltage across the discharge lamp 5 during no-load is close to When the discharge lamp 5 is fully lit, it is necessary to set the frequency Y' so that the lamp current can be reduced by satisfying the condition y'>x'; If the discharge lamp 5 is dimmed and lit when switched by X', the frequency Y' needs to be set so as to satisfy the condition Y'<X' and increase the lamp Wi current. The reason for setting as above is that as the switching frequency becomes higher, the impedance of the inductor becomes higher and the lamp current decreases.

Here, the operation will be explained based on FIGS. 2 and 3 in the case where frequencies X' and Y' satisfy the condition y'>x'.

Figure 2 shows the waveforms of each part when all lights are on, (A) is the rectified power supply voltage, (B) is the frequency switching signal obtained from the control circuit 3', (C) is the lamp voltage, and (D) is the lamp current. It is. Figure 3 shows the waveforms of various parts during dimming lighting, (A> is the rectified power supply voltage, (B) is the frequency switching signal obtained from the control circuit 3', (C) is the lamp voltage, and (D) is the lamp It is an electric current.

In this discharge lamp lighting device, when the lamp is fully lit, the pulse duty of the frequency switching signal is zero as shown in Fig. 2 CB).
For the entire duration of each cycle, the switching frequency is
', the discharge lamp 5 is fully lit, and the lamp voltage and lamp current become as shown in FIGS. 2(C) and 2(D), respectively.

When the dimming operation is performed, a pulse appears in the frequency switching signal as shown in FIG. 3(B), and the duty of this pulse increases as the dimming becomes deeper. During this pulse period, the switching frequency increases to Y', and as a result, the impedance of the inductor Lo increases, causing the lamp current to decrease as shown in FIG.
is dimmed. At this time, the degree of dimming is determined by the pulse width of the frequency switching signal shown in FIG. 3(B) and the switching frequency Y' during that period. Note that switching is always performed at frequency X' during the period from the beginning of each cycle until the restriking voltage is reached, so that the restriking time is not delayed.

In this way, the rectified power supply voltage is switched at the frequency Y' (KHz) in an arbitrary first period after the restriking of each cycle, and the second period other than the above-mentioned first period of each cycle is switched at the frequency X. ' (KHz), the period until re-ignition in each cycle is switched at a frequency X' close to the resonant frequency fo of the inductor LO and capacitor Co, and the voltage applied to the discharge lamp 5 increases. The period until the discharge lamp 5 is re-ignited can be shortened, and the lamp power factor and lighting efficiency can be increased.

In addition, by changing the ratio of the second period of switching at frequency X' and the first period of switching at frequency Y', the lamp current flowing during each cycle is changed,
The discharge lamp 5 can be dimmed by simply changing the width ratio between the second period of switching at frequency X' and the first period of switching at frequency Y', that is, two types of frequencies X' , Y', continuous dimming is possible. Furthermore, the switching frequency is 20KHz~4
When used in the 5 KHz range, the problem of continuous dimming by frequency being difficult due to remote control problems can be solved by optimally setting only two frequencies.

FIG. 4 is a block diagram showing a specific configuration of the control circuit 3'. In FIG. 4, ErN is a rectified power supply voltage, and this voltage EIN is connected to resistors R1, R2 + Zener diode Z.
D is divided into monostable multi-vibration IC, (ICM
7555i (manufactured by Intersil) is added to the 2nd terminal (trigger input terminal).

This monostable multivibrator IC is triggered when the rectified power supply voltage BIN exceeds a predetermined value, and the variable resistance V
R, , generates a pulse with a pulse width determined by the time constant of capacitor c3. Note that this pulse occurs during the first period of each cycle of the rectified power supply voltage (after restriking), and corresponds to the frequency switching signal in Figures 2 (B) and 3 (B). do.

The output of the 3rd terminal of the above monostable multi-by break IC is astable multi-by break IC2 (ICM7555
Resistor R3, which determines the oscillation frequency of the Intersil Corporation)
R, is applied via an inverter IN to a transistor Q3 which short-circuits variable resistor VR2 of variable resistor R2.

Hence, a monostable multi-bibreak IC.

During the pulse generation period (H level period), the transistor Q3
is off, astable multivibrator IC2 is 2Y'(
During the period other than the above (L level period), the transistor Q3 is on, and the astable multi-vibration IC2 oscillates at 2X' (KHz).

The output of pin 3 of astable multi-by-break IC2 is:
Flip-flop IC3 (μPD4013BC: NE
(manufactured by Company C), which is frequency-divided by 1/2 and divided into positive-phase and negative-phase signals.
C4 (μPD4011BC; manufactured by NEC Corporation) in addition to the drive circuit DR, the switch element Q1. Q2 is turned on and off alternately. Above Nant Gate Group IC
4 is the on-time of the switch element Q and the switch element Q2.
It has the effect of creating a rest period between the on periods of the

Then, by adjusting the variable resistor VR, the pulse width of the monostable multivibrator IC changes, that is,
By changing the length of the first switching period at frequency Y' (KHz) and adjusting variable resistor VH2, the value of frequency Y' is changed and set to a predetermined value.

A second embodiment of this invention is shown in FIGS. 5 and 6 FI! The explanation will be based on J. This discharge lamp lighting device, as shown in FIG.
′, the output of this high frequency inverter circuit 2′ is applied to the load circuit 4.

, the high frequency inverter circuit 2'' includes switch elements Ql, Q
2, a capacitor C4, and a transistor T, and operates as follows in response to a signal from control circuit 3#. That is, the switch element Q.

is on and switch element Q2 is off, the rectifier circuit l
A current flows through the positive terminal of the switch element Q, - the capacitor C4, the a terminal of the primary winding of the transformer T, the same terminal, and the fish species of the rectifier circuit 1, and the capacitor C4 is charged with electric charge. After this, switching Ql.

There is a period (rest period) in which both Q2 are off, and then when switch element Q1 is turned off and switch element Q2 is turned on, the charge stored in capacitor C4 is transferred to capacitor C4 - switch element Q2 - 1 of transformer T. Discharge occurs along the path from the B end of the next winding to the A end of the next winding and the capacitor C4, and then there is another rest period, and the inverter operation is performed by repeating the above operation.

As shown in FIG. 6, the above-mentioned control circuit 3# connects the rectified power supply voltage BIN to a resistor R11 and a variable resistor VRl.

As shown in FIG. 7(A), the divided voltage EIN'
and reference voltage Vo by comparator TC6 (μPC311
1NEc) and compared the results of this comparison (Figure 7 (B)
), the transistor Q5 is turned on and off according to the following. As a result, the oscillation circuit IC.

(manufactured by IN9494i Sharp ■) The oscillation frequency of the switch element Ql changes and is driven by the drive circuit DR,
The switching frequency of Q2 will change. That is, during the H level period in FIG. 7(B), the transistor Q5
is turned on, resistor R13 of the resistors R12+R13 that determines the oscillation frequency of the oscillation circuit rc6 is short-circuited, and the oscillation frequency corresponds to the switching frequency Y'. During the L level period shown in FIG. When it is turned off, the oscillation frequency corresponds to the switching frequency X'.

, and by adjusting the variable resistor VR,
When the divided voltage EIN' is decreased from the solid line to the dashed line to the dashed-dotted line in FIG. It becomes short (duty becomes small) like the l line, and dimming is performed by this.

This embodiment has the same effects as the first embodiment described above.

〔Effect of the invention〕

The discharge lamp lighting device of the present invention switches the high frequency inverter circuit at a first frequency away from the resonant frequency of the resonant circuit during an arbitrary first period after re-ignition of the discharge lamp in each cycle of the rectified power supply voltage. In addition, during the second period other than the first period of each cycle, the high frequency inverter circuit was switched at a second frequency close to the resonant frequency, and the ratio of the first and second periods was made variable. The resonant voltage (no-load secondary voltage) increases during the period until the lamp is re-ignited, and the discharge lamp can be re-ignited at an early stage, and the lamp power factor and lighting efficiency can be increased. In addition, by changing the ratio of the first period of switching at the first frequency and the second period of switching at the second frequency in each cycle, dimming can be achieved simply by switching between two frequencies in each cycle. It can be carried out. Furthermore, even if the dimming is deep, the discharge lamp does not go out or flicker because the discharge lamp always switches at the first frequency during the period until it is re-ignited in each cycle.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of the first embodiment of the present invention, FIG. 2 is a waveform diagram of each part when all lights are on, FIG. 3 is a waveform diagram of each part when dimmed lighting, and FIG. FIG. 1 is a detailed circuit diagram of the control circuit, FIG. 5 is a circuit diagram of a second embodiment of the present invention,
Figure 6 is a detailed circuit diagram of the control circuit, Figure 7 is a waveform diagram of each part to explain its operation, Figure 8 is a circuit diagram of a conventional discharge lamp lighting device, and Figure 9 is when it is fully lit. FIG. 10 is a waveform diagram of each part during dim lighting, and FIG. 11 is a characteristic diagram of the voltage across both ends and switching frequency of the discharge lamp. ■... Rectifier circuit, 2... High frequency inverter circuit, 3
'... Control circuit, 4... Load circuit, 5... Discharge lamp, Lo... Inductor, co... Capacitor Figure 1 Figure 2 Figure 3 Figure 5 Figure 6 Figure 7 Figure 9 Figure 10

Claims (1)

[Claims] A rectifier circuit that rectifies an AC power source, a separately excited high-frequency inverter circuit that is supplied with power from the rectifier circuit, a load circuit that is configured to include a discharge lamp and a resonant circuit and that is supplied with power from the high-frequency inverter circuit, and the rectifier circuit. The switching frequency of the high frequency inverter circuit is shifted from the resonant frequency of the series resonant circuit during any first period after re-ignition of the discharge lamp of each cycle of the rectified power supply voltage applied to the high frequency inverter circuit from 1, and the switching frequency of the high frequency inverter circuit is set to a frequency of 1 during any second period other than the first period after re-ignition of the discharge lamp of each cycle of the rectified power supply voltage to the resonance of the series resonant circuit. and a control circuit for setting a second frequency close to the frequency,
A discharge lamp lighting device in which a ratio between the first and second periods is variable.