JPS61179098A - 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 and device for lighting a discharge lamp such as a high-pressure discharge lamp with large impedance changes, and relates to a reduction in size and weight.

[Background technology]

Since discharge lamps have negative voltage characteristics, stabilization means are required to keep them lit.

In conventional general lighting devices, the stabilizing means consists of a circuit such as a circuit coil, a transformer, etc., or a combination thereof, so that both dimensions and weight are large. In order to solve this problem, a discharge lamp lighting device has been proposed that uses semiconductor elements to perform high-frequency switching and is made smaller and lighter.

FIG. 9 shows a circuit diagram of an example of a conventionally proposed discharge lamp lighting device using a DC chip type discharge lamp using a semiconductor. In FIG. 9, 1 and 2 are DC power supply voltage vD
Terminal to which o is applied, Q is a transistor, R8 is a current limiting resistor, 3 is a control circuit for the transistor Q, 4 is a current limiting transformer, 5 and 6 are current limiting transformers 4
The primary and secondary windings, the D section is an R-flow diode, the C section is a capacitor, and LA is the load, which is a high-pressure discharge lamp. The control circuit 3 operates depending on the current detection result by the current limiting resistor R8, and holds the transistor Q until the current in the secondary winding 6 becomes zero, and the current in the secondary winding #lI6 becomes zero. [After becoming the current engineer of the transistor Q engineer. , operates to turn on for a period of time until reaches a predetermined value.

FIG. 10 is a waveform diagram showing current and voltage waveforms of various parts of the high-pressure discharge lamp LA in the discharge lamp lighting device of FIG. 9 during steady state. Hereinafter, with reference to this figure, the circuit operation of the discharge lamp lighting device shown in FIG. 9 during normal operation will be described in detail. At time t, transistor Q is forward biased, and the collector-emitter voltage of transistor Q is V. 8 becomes zero, and a gradually increasing current I flows through the transistor Q. When the voltage across the current limiting plate resistor R8 reaches a predetermined value at time t2, the base current of the transistor Q becomes zero. Therefore, transistor Q1 is turned off and the current is turned off. , becomes zero. When the current IQ becomes zero, an induced voltage is generated in the primary winding 5 of the current limiting transformer 4, the diode conductor becomes conductive, and the current gradually decreases. The work is flowing.

And electrician. , becomes zero, forward bias is applied again to the transistor Q at the 9th time t, and the above-mentioned 9 operations are repeated, causing 1 to flow through the high-pressure discharge lamp LA.
flows, and the high-pressure discharge lamps I and A remain lit. In this case, the switching frequency f of the transistor Q
When the period of the current ILA is T, the t is 1/T.

FIG. 11 is a waveform diagram showing current waveforms at various parts of the discharge lamp lighting device of FIG. 9 immediately after the high pressure discharge lamp LA is started.

Hereinafter, with reference to this figure, the circuit operation immediately after the start-up of the discharge lamp lighting device shown in FIG. 9 will be described in detail. High pressure discharge lamp LA is
Immediately after starting, the lamp voltage vLA is as low as about 10 to 30V, and increases with time. Immediately after this start, the situation is close to a short circuit, the flow of current becomes steeper, and the voltage across resistor R8 becomes higher, so the range between 1 and 1 becomes narrower. On the other hand, between 11 and 12, the first volume is #! If the inductance of 5 is L and the equivalent resistance of the high pressure discharge lamp LA is R, then the time constant T of the circuit is expressed as 1. The current ID decreases with R. When starting, the equivalent resistance R is small, so the time constant T. , is large, the period T2 is large, and the switching frequency (lighting frequency) of the transistor Q at the time of starting is f2
(=1/41″+2) becomes very low, and the audible frequency f
Sometimes it goes down to band 8.

Other details are the same as those described in the steady state description.

FIG. 12 is a waveform diagram showing current waveforms at various parts of the discharge lamp lighting device of FIG. 9 when the lamp voltage vTJA of the high-pressure discharge lamp LA at the end of its life increases abnormally (when the impedance increases abnormally). The operation of the high-pressure discharge lamp LA of the discharge lamp lighting device shown in FIG. 9 at the end of its life will be described below with reference to this figure.

The equivalent resistance R of the high-pressure discharge lamp LA increases as the lamp voltage V□ increases, and c-1fwJ becomes slightly longer because the difference between the Lande voltage v1 and the DC power supply voltage vDo decreases, but 12-11 The period T3 is substantially reduced, and the switching frequency (lighting frequency) f3 (=1/T3) of the transistor Q is increased. In such a state, transistor Q and diode D
As the switching loss of the equipment increases, the problem of noise arises.

FIG. 13 is a diagram showing the relationship between lamp voltage ■LA and lighting frequency f. In Fig. 13, f is the switching frequency (lighting frequency) during steady state, f2 is the switching frequency (lighting frequency) at startup, f3 is the switching frequency (lighting frequency) at the end of life, and the upper limit of fcji town frequency ( 15 to 20 degrees).

In the discharge lamp lighting device using the voltage-horse wave number control method (corresponding to pulse width control) as described above, the high-pressure discharge lamp L
When A is the load, the lamp voltage vLA changes significantly, so the switching frequency f drops to an audible frequency ° at startup, causing a noise problem.On the other hand, the lamp voltage vLA at the end of the life of the high-pressure discharge lamp LA When the switching frequency f increases, the switching frequency f shifts to a higher frequency f3, which increases circuit loss and increases the noise level. An object of the present invention is to provide a discharge lamp lighting device that can reduce power loss.

[Purpose of the invention]

A discharge lamp lighting device of the present invention includes a discharge lamp with a large impedance change, a semiconductor switching element that provides a high-frequency output to the discharge lamp, and a switching frequency of the semiconductor switching element that changes according to a change in the impedance of the discharge lamp. A control circuit is provided, and the switching frequency of the semiconductor switching element is regulated to a frequency substantially equal to or less than the switching frequency of the discharge lamp during normal operation.

In this way, the switching frequency of the semiconductor switching element is regulated to a frequency that is approximately equal to the switching frequency in steady state or less, so even when the discharge lamp reaches the end of its life and the impedance increases abnormally, the switching frequency will become abnormally high. This eliminates the problem of noise.

In addition, since the switching frequency is regulated, there is a pause period in the lamp current at the end of its life, making it easier for the discharge lamp to go out. This can be notified by turning off the light.

Embodiment A first embodiment of the present invention will be explained based on FIGS. 1 to 4 and FIG. 8. This discharge lamp lighting device has a first
As shown in the figure, the DC power supply voltage vD.

A transistor Q is applied between power supply terminals 2 and 1.

1. Connect the series circuit of 1.-Kucoil L. and high-pressure discharge lamp. Connect the capacitor port in parallel to the high-pressure discharge lamp. A series circuit including a freewheeling diode and a current detection resistor R0 is connected in parallel.

Then, the current flows into the freewheeling diode D. , is inspected with the current detection R0, and the basic single voltage ■RIiF is inspected with the resistor R6.
Divide the voltage at ゜ and get the voltage vR7 of resistor R9 and the voltage of resistor R8.

Compare with the comparator. As a result, vR7
When V, the comparator output voltage VB>1”H”
It becomes RO2. The output voltage of this comparator is VB, and the resistance is R.
A resistor R4 is connected in series to the transistor Q2.
, R5, and when the output voltage VB of the Humbaletae is "H", the transistor C2 is turned on and the tie Y (I C555: manufactured by μPC15551y)
, the input of the glue set terminal C is set to "L" and the timer 2 is reset.

The timer I has an output terminal ■, a reset terminal ■, a trigger input terminal @, and an open collector output terminal O.

When the voltage of capacitor C2 becomes (V3) Voo, it is triggered and the output terminal
The voltage vA of the capacitor becomes 6H. Also, when the capacitor voltage V.2 becomes (2/3) Voo, the output terminal [1'EVA becomes "L" and the open collector output terminal becomes "L". ”, and the charge of capacitor C2 becomes C
2-R2-■-■ is discharged in the closed circuit, and the voltage of capacitor C2 is V. 2 decreases. When the voltage v02 of the capacitor C2 becomes (1/()voo), the open collector output terminal (2) turns off and the voltage vA of the output terminal (2) becomes H''.

On the other hand, when the input of the reset terminal ■ becomes L'' due to the transistor Q2 being turned on, the voltage vA of the output terminal ■ becomes L'', and a closed circuit of C2-R2-■-■ is formed, but the input of the reset terminal ■ When the voltage V of capacitor C2 is maintained at L", the voltage at the output terminal ■ does not reach H" even if it becomes less than (1/3) vo.
I am interested in maintaining this state. In other words, electrician. , is flowing and the output voltage VB of the comparator I2 is 1H'', the transistor Q2 is on and the input to the reset terminal ■ is 6L'', so the output voltage VB of the comparator I2 is
The voltage at output terminal ■□ is H unless E becomes 6L''.
”.However, please be sure that the voltage vA of the output terminal ■ is
Hπ null means that the voltage V of capacitor C is (1/3)
Vo.

2 Timing and comparator value below C2. output voltage V
The oscillation frequency f' of the timer (the maximum value of the switching frequency of the 1-9 transistor Q) is the later timing of the timing when B becomes "L".
, and the time constant of the capacitor C2. Even if the input to the reset terminal (2) is 6H", that is, the output voltage VB of the comparator (2) becomes "L" quickly, the oscillation frequency will not become higher than that.

7 is a base drive circuit of the transistor Q2, and when the voltage vA of the output terminal ■ is "H", the transistor Q2 is
is turned on, and when the voltage vA at the output terminal (2) reaches 6L'', the function transistor Q2 is turned off.

D2 is a diode, and C3 is a capacitor.

@Figure 2 shows the voltage R of each part in the steady state of the circuit in Figure 1.
't! f shows a pressure waveform diagram. In Figure 2, ■
is the voltage of the timer's output terminal ■, the current of the ILL gate coil L, and ■. , is the current of freewheeling diode D, ■
is the output voltage of comparator I2.

vh is the voltage of fundensor C, (1/3') Vo
.

It varies in the range from C1-/2 to (2/3') V,o. During steady state, it operates at approximately 50% duty, and the oscillation frequency f'1 (= "/T') at this time is approximately equal to the basic oscillation frequency (determined by R□, R2, and C) of the timer. , is operating as an astable multivibrator).

Figure vg3 shows the current and voltage waveform diagram of each part in the circuit of Figure 1 at the end of its life. When the high-pressure discharge lamp LA reaches the end of its life, the lamp voltage VLA increases, its equivalent resistance R increases, and the time constant TLR shortens (12-
13 hours). Since the oscillation frequency f'3 is fixed by a timer, it becomes T'*T]', and the lamp voltage vLA
does not rise and become high, it is almost the same as in the steady state, and 1
A lamp current pause period occurs between 3 and 10 minutes.

FIG. 4 shows current and voltage waveform diagrams of various parts of the circuit of FIG. 1 immediately after starting. The oscillation frequency f' at steady state and at the end of life is determined by the resistor R of the timer.

9 determined by R2 and capacitor C, but at startup, 12-1. The period (ToFIF) is long, and the release of the reset by the timer and the glue set terminal (2) is delayed, and the oscillation frequency f' decreases. Here, the oscillation frequency fi at startup
(ff1l/T'2) is T between t knee t8 to make the audible frequency higher than f3. The N time is as follows.

Chi, - Electrician of Kucoil L Engineering. , the peak current of
The lamp voltage v, A immediately after starting is vF, -ku coil L
Let L be the inductance of T, and T. P.F.
teeth.

It can be found by

The period T1 at the time of starting is T'=T+TOIPIP 2 ON And MakyuT. FF is vF D.C. = (--1') ToN V.

becomes. As a precaution, T'``TON'' TOFF is set as follows.If To and Y satisfy the above expression, the oscillation frequency f' will not drop to an audible frequency at the time of starting. However, fs-1/T8.

FIG. 8 is a diagram showing the relationship between lamp voltage vLA and oscillation frequency f' in the above embodiment. In Figure 8, f
l is the frequency at steady state, f2 is the frequency at startup, and f8 is the upper limit of the audible frequency (15 to 20 KH).

The upper limit of the oscillation frequency f' is approximately fl due to regulations such as timers, and the lower limit is f8 or higher depending on the ToN time setting.

Like this, this sj! In this embodiment, the upper limit value of the oscillation frequency f' of the timer I2 is set to a frequency close to the oscillation frequency f' during normal operation, so that even if there is an abnormal rise in the lamp voltage vLA at the end of the life of the high-pressure discharge lamp LA, the oscillation frequency remains unchanged. f' does not rise, a pause period occurs in the lamp currents In and A, and the high-pressure discharge lamp LA, which has reached the end of its service life, ends up extinguishing, causing increased noise and light, causing the failure of the Tofunjista Q construction.

Diode 01 table does not increase any switching loss.

Furthermore, since the TON time is set to a predetermined value, the oscillation frequency f' does not fall at the audible frequencies f and t at the time of startup, and the problem of noise can be solved.

In addition, in the process of transition from startup to steady state, the oscillation frequency f' changes in accordance with the change in lamp voltage VLA, and it is possible to supply the high-pressure discharge lamp LA with a lamp ti without a pause period. It is possible to stably transition the high pressure discharge lamp LA from startup to a steady state.

A second embodiment of the invention will be explained based on FIGS. 5 to 7. As shown in FIG. 5, this discharge lamp lighting device has transistors Q3 to Q6 connected in a bridge configuration between terminals 2 and 1, and diodes D5 to Q4.
D4 are connected in parallel via the current detection resistor R0,
Transistor Q, 3. Connection point of Q4 and transistor Q
A series circuit of choke coil L2 and high-pressure discharge lamp LA is connected between the connection points of , , 0.6, and high-pressure discharge lamp L
A capacitor C4 is connected in parallel to A.

This discharge lamp lighting device uses, for example, several hundred transistors Q
4. Q is turned on and off alternately, and when the transistor Q6 is turned on, the voltage difference Q3 becomes 50Kt&
On/off (variable duty ratio on/off operation) L
, , ) When the fungistor Q is turned on, the transistor Q6 (not shown) is also turned on and off as usual. In this case, the control circuit CT turns on the transistor Q3 again when the current of the diode D3 reaches zero based on the voltage drop across the current detection resistor R8, and turns on the transistor Q3 again when the current of the diode D4 reaches zero. Transistor Q5t - Turn on again.

The switching operation of the queen transistors Q3 to Q6 is such that when transitioning from the startup to the steady state, the lamp voltage vLA gradually increases (a benefit of the impedance R of the high-pressure discharge lamp LA gradually increasing). Diode D3
* The timing at which the current in D4 becomes zero gradually becomes earlier, and the switching frequency of transistor Q3.05 increases.
That is, the lighting frequency is lowest at the time of starting, and gradually increases as it approaches a steady state.

Note that even if the lamp voltage becomes higher at the end of its life, the lighting frequency will hardly become higher than the frequency during normal operation.

Next, the configuration and operation of the control pipe are shown in Figures 6 and 7.
This will be explained using figures. In Fig. 6, the oscillation circuit 8 is operated at a cost of several hundred yen (waveform in Fig. 7 (2)), and the 7-lip 70-tub circuit 9 extracts two signals (waveforms in Fig. 7 [Bl, FC)]. Then, the do-wipe signals of the positive half cycle and the negative half cycle of the lamp currents I and A (Fig. 7) are obtained. This signal is sent to the base drive circuit 13.10 of the transistors Q, Q6, which are turned on and off in several hundred µL. On the other hand, transistor Q3 is turned on and off at tens of K)h.
．． The timer (
IC555: μPCl555: [manufactured by the company] The output signal of the IC and the output signal of the flip-prop circuit 9 are combined by the AND element 3' I4, and 9 signals are given.

Current detection resistor R0 is connected to diode D3. Detect the current of D.

Note that the operations of *+t in the comparator, timer, etc. are the same as those shown in FIG. 1, so a description thereof will be omitted.

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

〔Effect of the invention〕

In the discharge lamp lighting device of the present invention, the switching frequency of the semiconductor switching element is regulated to a frequency that is approximately equal to the switching frequency in steady state or less, so that even when the impedance increases abnormally at the end of the life of the discharge lamp, the switching frequency remains constant. will not become abnormally high, and the problem of noise can be solved. Furthermore, since the switching frequency is regulated, there is a pause period in the lamp current at the end of its life, making it easier for the discharge lamp to go out. This can be communicated by turning off the lights.

[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 during steady state, vJa diagram is a waveform diagram of each part at the end of its life, and Fig. 4 is a diagram of the waveforms of each part at the end of its life. FIG. 5 is a circuit diagram of the second embodiment of this invention,
FIG. 6 is a detailed circuit diagram of the main parts, FIG. 7 is a waveform diagram of each part in FIG. Figure 9 is a circuit diagram of a conventional discharge lamp lighting device, Figure 10 is a waveform diagram of each part during its steady state, and Figure 11 is a waveform diagram of each part immediately after startup, and ν.
The figure is a waveform diagram of each part at the end of its life, and FIG. 13 is a diagram showing the relationship between the lamp voltage vLA and the switching frequency in a conventional example. LA...High pressure discharge lamp, Q engineering...Transistor (semiconductor switching element), D□... Free wheel diode, ■
2...Comparator (control circuit), I,...Timer (control circuit) Fig. 2 Fig. 3 Fig. 4 (A) (C) (E) Fig. 7 Grain f Fig. 13 1'# Fruit #Lf' Fig. 8 l No. 9! ! ll Figure 10 Figure 12

Claims (1)

[Claims] A discharge lamp with a large impedance change, a semiconductor switching element that provides a high frequency output to the discharge lamp, and a control circuit that changes the switching frequency of the semiconductor switching element in accordance with a change in impedance of the discharge lamp, A discharge lamp lighting device in which a switching frequency of an element is regulated to a frequency substantially equal to or less than a switching frequency of the discharge lamp during normal operation.