JPS6337955B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a discharge lamp lighting device that uses a light bulb as a ballast for a fluorescent lamp.

In recent years, some fluorescent lamps have used light bulbs as resistive ballasts. On the other hand, discharge lamps have the disadvantage of poor color rendering. Therefore, in recent years, attempts have been made to use light bulbs as resistance ballasts in fluorescent lamps to improve the poor color rendering properties of fluorescent lamps by improving the color rendering properties of light bulbs.

However, the light bulbs used as resistance ballasts in the past were commercially available incandescent light bulbs, and were not designed with the characteristics of discharge lamps as ballasts in mind. Therefore, it could not be said that this light bulb sufficiently stabilized the discharge of a fluorescent lamp. For example, there has been a drawback that the lamp may go out due to an increase in tube voltage caused by a low-temperature atmosphere such as in a cold region or a drop in power supply voltage.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a lighting device in which the discharge of a fluorescent lamp is stabilized against the above fluctuations by regulating the characteristics of a light bulb as a resistance ballast of the fluorescent lamp.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

In this device, a light bulb 2 and a fluorescent lamp 3 are connected in series to an AC power source 1. The light bulb 2 functions as a resistance ballast and provides stable lighting of the fluorescent lamp 3. Incidentally, a lighting tube 4 is connected in parallel to the fluorescent lamp 3 as a starting device.

Here, the resistance value of the light bulb 2 is R [Ω], and the current value flowing through the light bulb 2 and the fluorescent lamp 3 is Ie [A], then R=kI ⁿ _e n ≧ 0.85 (k: constant of proportionality)...(a ), and furthermore, the current value Ie [A] short-circuits the fluorescent lamp 3 and connects the lamp 2 directly to the AC power supply 1.
If the short-circuit current value when connected is Ish [A], then 0<Ie<Ish...(b) is satisfied.

The above formulas (a) and (b) will be explained below. Generally speaking, in a discharge lamp itself, when the current Ie increases, the tube voltage increases.
It exhibits a so-called negative characteristic in which Ve decreases.
This is expressed as Ve=f(Ie)...(c) and is shown by curve A in Figure 2.

In addition, in the fluorescent lamp lighting device shown in FIG. 1, the sum of the voltage drop RIe at the light bulb 2, which is a resistance ballast, and the voltage Ve across the fluorescent lamp 3 is equal to the power supply voltage Vs [V], so Vs=RIe+Ve... (d) holds true. In equation (d), the resistance value R [Ω] of the light bulb 2 is a function of current, and in the case of an incandescent light bulb, it is generally expressed by the following approximate equation.

R≒k(Ie) ⁿ (k: positive proportionality constant)...(e) Substituting equation (e) into equation (d), we get Ve=-k(Ie) ⁿ⁺¹ +Vs...(f), and this Equation (f) is generally indicated by curve B in FIG.

The fluorescent lamp lighting device in Figure 1 is based on formulas (c) and (f).
must be satisfied at the same time. The operating point of the discharge lamp is the intersection point A and B of curve A and curve B in Figure 2.
It is expressed as

By the way, since discharge lamps generally have negative characteristics, the stable operating point of the positive column must satisfy the following equation. That is, when Ie≧Ish, dIe/dt<0...(g) When Ie<Ish, dIe/dt>0...(h).

In addition, in Fig. 2, the shaded area with curve A as the border is the area where dIe/dt > 0, and the rest is the area where dIe/dt
<0 region. Therefore, the stable discharge operating point of the discharge lamp is point B.

This is because, suppose the discharge operating point is at point A. Suppose that the discharge operating point deviates from point A and moves on curve B. At this time, if Ie increases and the operating point enters the shaded area, this area is dIe/dt
>0, the discharge operating point further moves on curve B in the direction of increasing current, and the discharge operating point does not return to point A. Conversely, Ie decreases and the discharge operating point becomes A.
If the discharge operation point deviates from the point and enters the shaded area, since dIe/dt<0 in this area, the discharge operating point moves further on the curve B in the direction in which the current decreases. At this time, Ie continues to decrease and the discharge lamp goes out. Therefore, point A is not a stable discharge operating point.

Next, let's consider point B. If Ie increases and the discharge operating point moves to a region not shaded, Ie will decrease and the discharge operating point will return to point B because dIe/dt<0 in this region. On the contrary, Ie
Assume that the discharge operating point moves from point B to the shaded area on curve B as a result of decrease in the discharge operating point. In this region, dIe/
Since dt>0, Ie increases and the discharge operating point attempts to return to point B on curve B. Therefore, point B is the stable discharge operating point.

As mentioned above, the stable discharge operating point is point B, but
In a case like curve C which has only one common point C with curve A, the discharge operating point always moves in the direction in which the current Ie decreases, so point C cannot be a stable operating point.

As described above, in order for the discharge lamp to obtain a stable discharge operating point, curves A and B need to have two intersections. For that purpose, dIe/dt determined by curve A
It is necessary to expand the region >0 or increase the curvature of curve B representing the bulb characteristics. Here, curve A is determined by the characteristics of the discharge lamp, but since discharge lamps are designed from the standpoint of efficiency, their characteristics are also determined naturally. Therefore, it is necessary to obtain a stable discharge operating point by increasing the curvature of curve B. However, it is the order n in equation (f) that determines the curvature of curve B. When the value of n is decreased, the curvature is also decreased. For example, when n is decreased too much, the state of curve C in FIG. 2 is reached, and there is no stable discharge operating point. Therefore, the value of n must be set to a certain value or more.

On the other hand, FIG. 3 illustrates the fluctuation of the discharge stable operating point with respect to the fluctuation of the power supply voltage. Among them, curve A is an illustration of equation (c) indicating the discharge characteristics, and curves D and E are curves with different values of order n in equation (f), and the discharge is stable when Vs = 100%. This is a curve with matching operating points. where the power supply voltage
When Vs fluctuates by ±10%, the stable discharge operating point changes by ΔI ₁ for curve D and by ΔI ₂ for curve E, based on the current value. At this time, ΔI ₁ <ΔI ₂ holds, which means that the larger the value of the order n, the smaller the variation in the discharge stable operating point.

Further, FIG. 4 illustrates the fluctuation of the discharge stable operating point with respect to changes in ambient temperature. Curves D and E show current-voltage characteristics when the value of n is different. On the other hand, curves A and F respectively illustrate equations (c) representing the discharge characteristics, and in contrast to curve A, curve F represents the characteristics when the ambient temperature decreases. In this figure, the discharge stable operating point changes with respect to changes in ambient temperature in terms of current, which changes by ΔI ₃ for curve D and by ΔI ₄ for curve E. At this time, ΔI ₃ <ΔI ₄ , and from this it can be seen that the larger the value of the order n, the smaller the variation in the discharge stable operating point.

Now, from the above explanation, it can be seen that the worst condition for lighting the discharge lamp is when the power supply voltage Vs fluctuates in the negative direction in a low temperature atmosphere. At this time, the value of n for the existence of a stable discharge operating point was determined through experiments. For example, if the power supply voltage is 90% Vs = 90 [V],
JIS standard 5 to prevent atmospheric temperature from disappearing
Regarding °C, when various fluorescent lamps are turned on, n is
It was confirmed that if the value was 0.85 or higher, the fluorescent lamp would not go out. Incidentally, in conventional fluorescent lamp lighting devices, n is around 0.80 or less.

Next, the ballast loss (W _R /W _io ), which is expressed as the ratio between the power W _R consumed by the light bulb 2, which is the ballast resistor, and the input power W _io is determined from equation (e).

W _R = RI ² _e = kIe ⁿ⁺² W _io = IeVs Therefore, W _R /W _io = kIe ⁿ⁺² /IeVs = kIe ⁿ⁺¹ /Vs Here, if Ie is expressed by the parameter of t, the formula (b )
Therefore, Ie=tIsh (0<t<1), and W _R =W _io =(kI ⁿ⁺¹ _sh /Vs)t ⁿ⁺¹ ...(i) This is illustrated in FIG. The horizontal axis is the current
The value of t, which means Ie, is taken, and W _R /W _io is shown on the vertical axis. It can be seen that the ballast loss changes by varying the value of n, and the larger the value of n, the smaller the ballast loss can be.

The value of n is determined by the light bulb as a resistance ballast, but this value can be increased by changing the shape of the filament or by increasing the pressure of the argon or krypton gas sealed in the light bulb.

As explained above, according to the present invention, since the characteristics of the light bulb are regulated, the discharge of the fluorescent lamp is sufficiently stable and there is no possibility of the lamp going out. Furthermore, fluctuations in the discharge operating point of the fluorescent lamp due to fluctuations in power supply voltage and changes in ambient temperature are also reduced, and ballast loss can also be reduced.

Note that the above-mentioned concept can be applied to discharge lamps in general.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a fluorescent lamp lighting device of the present invention, and FIGS. 2 to 4 are current-voltage characteristic diagrams showing discharge characteristics. Further, FIG. 5 is a characteristic diagram showing the ballast loss. 1...AC power supply, 2...light bulb, 3...fluorescent lamp,
4...Lighting tube (starting device).

Claims (1)

[Claims] 1. An AC power source, a light bulb as a resistance ballast,
In a fluorescent lamp lighting device comprising a fluorescent lamp connected to the AC power source via the light bulb and a fluorescent lamp starter connected in parallel to the fluorescent lamp, the light bulb has R=kI ⁿ A fluorescent lamp lighting device characterized by having characteristics satisfying the following: _e , n≧0.85 (k is a positive proportionality constant). (However, the resistance value of the light bulb is R [Ω], the current flowing through the light bulb and fluorescent lamp is Ie [A], and the current value when the fluorescent lamp is short-circuited is Ish [A].)