JPS60148098A - Device for firing discharge lamp - 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 lighting a high pressure discharge lamp at high frequency.

[Background technology]

BACKGROUND ART There has been a strong desire for discharge lamp lighting devices to be smaller, lighter, and have lower loss. However, in conventional general discharge lamp lighting devices, choke coils, trasses, capacitors, etc. are used singly or in combination, resulting in large dimensions and weight. In particular, the size of high-pressure discharge lamps is smaller than that of fluorescent lamps, so when considering a built-in lighting device, there is a problem that a large storage space cannot be secured for the lighting device. For fluorescent lamps, high-frequency lighting devices using switching transistors and the like have been put into practical use with the aim of reducing the size and weight of the lighting device, reducing loss, and improving luminous efficiency. Such a high-frequency lighting device has the same effect as a fluorescent lamp even when applied to a high-pressure discharge lamp, and its practical use is eagerly awaited.

However, it has been known that arc instability (fluctuation, extinction, arc tube destruction, etc.) due to acoustic resonance occurs during high-frequency lighting of high-pressure discharge lamps (Journal of App. Eye edPhysic
s-49(5), May 1978 P2680-2
683 and its references). Various methods are known to prevent this, such as rectangular wave lighting and frequency limitation (for example, IES TRANSACTION Il
:CEMBER1q6q ゝゝ In1tial Ch
aracteristics of Higb Int
energy discharge lamps on
Higb Frequency Power'').

The formation mechanism of arc instability that occurs during high-frequency lighting of a high-pressure discharge lamp as described above is thought to be as follows. That is, first, a high-frequency passive motion of the electrical input is generated, which causes a pressure change in the gas inside the arc tube, and a standing pressure wave is generated at a special frequency [7. The arc becomes unstable due to pressure amplitude exceeding the limit. This means that sagging occurs. Here, the "special frequency" is the so-called acoustic resonance frequency, which is determined by the dimension of the arc (actually, the shape of the arc tube) and the speed of sound inside the arc tube. Since the average molecular weight and sulfur temperature of the waste in the pipe are determined,
Once these values are known, it is relatively easy to determine 1n''j.On the other hand, it is difficult to determine at which acoustic resonance frequency the above-mentioned ``arc instability due to pressure amplitude exceeding the limit'' occurs. , it is a problem in the nonlinear domain, and the answer cannot be simply determined.

However, in the process of studying high-frequency lighting of a high-pressure discharge lamp, the inventor found that the following technical problems existed. In other words, even if the design is such that arc instability due to acoustic resonance does not occur at rated lighting during steady lighting (this can be achieved, for example, by limiting the lighting frequency), it is difficult to dim a high-pressure discharge lamp. This means that arc instability will occur if the arc is used in this way. It is presumed that such a problem occurs for the following reasons. In other words, during dimming, compared to steady lighting,
The conditions of the arc have changed, and therefore both the above-mentioned "special frequency", i.e., the acoustic resonance frequency, and the pressure amplitude above the limit at that frequency, i.e., the susceptibility of the arc to instability. Even if the lighting frequency is designed to avoid acoustic resonance during steady lighting,
In the case of dimming, the arc becomes unstable due to acoustic resonance due to the above-mentioned reasons, and it has been practically difficult to select a stable lighting frequency that spans both steady lighting and dimmed lighting.

Figure 1 is a diagram for explaining the above state.
(M250・L/BU) shows the stable lighting frequency range for each tube current (shaded area).As is clear from this figure, the stable lighting frequency at rated lighting and the tube current The stable lighting frequencies do not match perfectly when the dimming level is lowered, and the stable lighting frequency range becomes smaller as the dimming level is increased (if the rated tube current is lowered by half, the stable lighting frequency range disappears). There is.

), and considering variations in stable lighting frequency due to variations in discharge lamps, etc., it is virtually impossible to stably light both rated lighting and dimmed lighting at one frequency, for example.

[Object of the invention] □ The present invention has been made in view of the above points,
The object of the present invention is to provide a discharge lamp lighting device for lighting a high-pressure discharge lamp at high frequency, which is capable of eliminating arc instability that occurs during dimming.

[Disclosure of the invention]

The present invention solves the above-mentioned instability of the arc by lighting the high-pressure discharge lamp with a rectangular wave during dimming in a discharge lamp lighting device that lights a high-pressure discharge lamp at high frequency, and produces acoustic resonance when the rated output is lit. (1) in FIG. 2 showing the basic configuration of the present invention is a high-frequency rectangular wave lighting circuit which is a high-frequency rectangular wave lighting means that generates a rectangular wave dimming pressure; (2) is a sine wave and the high pressure discharge lamp (4) does not cause acoustic resonance) B
This is a high frequency sine wave lighting circuit which is a high frequency sine wave lighting means that generates a rated output in the wave number region, and (3) is a changeover switch element that switches between dimming and the rated output. However, by switching the lever changeover switch element (3), the output of the high-frequency rectangular wave lighting circuit (1) is connected to the high-pressure discharge lamp (4) during dimming, and the output of the high-frequency sine wave lighting circuit (2) is connected to the high-frequency sine wave lighting circuit (2) during rated output lighting. The output can be connected to a high pressure discharge lamp (4).

Embodiment 1 FIG. 3 shows a circuit of Embodiment 10, which uses a so-called self-excitation type 0 ise type inverter oscillation circuit.
Between the power supply Vs and the common connection point of the primary winding N of the oscillation transformer T, there is a changeover switch SW that is turned off during dimming.
and an intertasis element, and further interlocks with the changeover switch SW1 in series with the resonant condenser tc connected between both ends of the primary windings N1 and N'1 of the oscillation transmission T. The switch SW2 is inserted and connected. However, when the rated output is turned on, when the changeover switch SW1.5Wll constituting the changeover switch element (3) is turned on and the power supply VS is turned on, the starting current (the starting resistor is omitted in the drawing) will flow through the transistors Q1 and C2. The current flows to the base, and one of the transistors Q is turned on due to variations in the circuit constant, and thereafter, the constant of the transistor C is set appropriately by the action of the feedback windings NB and N'H of the oscillation transformer T. As a result, a high-frequency sine wave output in a frequency range where acoustic resonance does not occur is obtained from the secondary winding N2 of the oscillation truss T which also serves as a ballast, and the high-pressure discharge lamp (4
) can be lit at the rated output.

Next, if you want to switch the high pressure discharge lamp (4) from rated output lighting to dimming output lighting, turn off the changeover switch SW1 and insert an interface element in series with the power supply VS.
It is possible to dim the light by lowering the next output, but simply turning off the changeover switch SWl may result in different oscillation conditions or the occurrence of acoustic resonance as described above, which is inconvenient and undesirable. In the embodiment, the changeover switch S
The changeover switch SW2 is turned off in conjunction with the turning off of W1 to disconnect the resonance converter +jC from the primary side of the oscillation transformer T, so that a high frequency rectangular wave output can be obtained as a secondary output. Therefore, rectangular wave lighting can avoid acoustic resonance during dimming.

Embodiment 2 FIG. 4 shows Embodiment 2, which is composed of a separately excited half bridge type inverter. Q in the diagram
l, Q2 are main transistors, and these main transistors Q
, , C2 is driven as follows. That is, the DC power supply V's is voltage-divided by resistors R1 and R2, smoothed by a capacitor C3, and then the voltage VCC is first obtained through a constant voltage circuit consisting of a transistor Q5, a Zener diode 28, and a resistor R3. Then, a timer IC (5) (for example, NEC's tPC
A basic oscillation circuit consisting of I555CL resistors R6, R5, and a condenser is used to generate a signal with a frequency twice the lighting frequency of the high-pressure discharge lamp (4). and the AND gate circuit (7,)
, (7□) are used to generate 1/2 frequency-divided signals with opposite phases to each other, and these signals are connected to transistors Q8 and Q8, respectively.
In addition to the base of C4, transistors Q3 and C4 are alternately turned on and off, and main transistors Q1 and C2 are alternately driven via drive transformers T, T2.

Therefore,] capacitors C1 and C2, main transistor Q3
, C2, a high-pressure discharge lamp (4), and a half-bridge type inverter consisting of a current-limiting element operates in oscillation.

When lighting the high-pressure discharge lamp (4) at the rated output, switch SWo, which is the selector switch element (3), is turned to the ■ side, and the condenser C6 and the inverter system are connected in series to the high-pressure discharge lamp (4). It is sufficient to insert a current-limiting element consisting of Lo. In this case, the function of the current-limiting element applies a sinusoidal high-frequency output to the high-pressure discharge lamp (4), and the high-pressure discharge lamp (4) lights up at the rated output.

Next, when lighting the high-pressure discharge lamp (4) at the rated output, turn the switch SWo to the ■ side to change the current-limiting element connected to the high-pressure discharge lamp (4) to the resistor Rh, and then turn on the high-pressure discharge lamp (4).
The high frequency output applied to the lamp is made into a rectangular wave and lights up in a rectangular wave. At this time, the value of the resistor Rb is determined by the cocidenser C6 and the interface element. Dimming can be done by making the impedance larger than the current limiting element consisting of.

Of course, it goes without saying that the circuit constants are determined so that the oscillation frequency is set in a region where no acoustic resonance occurs.

In the figure, D and D are commutation diodes.

〔Effect of the invention〕

In the discharge lamp lighting device as described above, the present invention dims the high-pressure discharge lamp using a high-frequency rectangular wave during dimming. It is possible to avoid the acoustic resonance that occurs during dimming, and since the square wave is still used only during dimming, the noise has the effect of being low in power and does not become a problem.Furthermore, it uses a high frequency square wave lighting means using self-oscillation. However, there is also the effect that the loss does not become as large as the left.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing the relationship between the lighting frequency and tube current of a high-pressure discharge lamp, Fig. 2 is a schematic circuit diagram of the present invention, Fig. 3 is a circuit diagram of Example 1 of the same, and Fig. 4 is It is a circuit diagram of Example 2 same as the above, (4) is a high frequency rectangular wave lighting circuit, (2) is a high frequency sine wave lighting circuit, and (4) is a high pressure discharge lamp.

Claims (1)

[Claims] (1) A discharge lamp lighting device for lighting a high-pressure discharge lamp includes a high-frequency sine wave lighting means designed to a lighting frequency that does not cause acoustic resonance during steady lighting, and a high-frequency rectangular wave lighting means, and a high-frequency rectangular wave lighting device when dimming. A discharge lamp lighting device characterized in that the output of the wave lighting means is connected to a high pressure discharge lamp, and the high frequency sine wave lighting means is connected to the high pressure discharge lamp when the rated output is lit.