JPS60117162A - Method for judging life of discharge lamp - Google Patents

Abstract

PURPOSE:To accurately the life of a discharge lamp, by detecting the positive and negative asymmetry of both terminal voltages of the electrode filament of the discharge lamp during lighting. CONSTITUTION:In constitution consisting of a power source AC, a lighting circuit B, a fluorescent lamp FL and a starter S, a circuit J for detecting the positive and negative assymmetry of filament body terminal voltages Vf is connected to both terminals of the filament F of the fluorescent lamp FL and a display circuit Q is further connected. Filament body terminal voltages Vf are becomes high only in negative voltage with the elapse of lighting time and positive voltage is almost constant. In the detection circuit J, an integrator circuit is constituted of a resistor R1 and a capacitor C to detect the difference of DC components of filament both terminal voltages Vf and connected to the display circuit Q constituted of a resistor R2 and a light emitting diode D. By this mechanism, accurate lamp life can be judged.

Description

TECHNICAL FIELD The present invention relates to a method for determining the life of a discharge lamp such as a fluorescent lamp.

(Background Art) As a method of determining the lifespan of a fluorescent lamp, there is a known method of detecting the level of wear and tear of the electron radioactive material on the electrode (hereinafter referred to as electrode material) that progresses as the fluorescent lamp is lit. ing.

This determination method will be explained with reference to FIGS. 1 and 2. FIG. 1 shows the most common fluorescent lamp lighting circuit, and the mechanism for loss of electrode material in such lighting conditions is as follows.

A hot spot at the time of lighting is formed at the part closest to the power source in the area where other substances have adhered, and as the lighting progresses, the electrode material is gradually worn away from the end where the hot spot occurs (in other words, the hot spot is A <new> lamp with a short operating time is
As shown in FIG. 2 (al), the electrode material E is sufficiently deposited on the filament F, and a hot spot is formed at the power supply side end Pi of the filament F. Then, as the lighting time elapses, Electrode material E due to evaporation, scattering, etc.
gradually wears out from point Pi, passing through f4S2 (bl) and moving to the state shown in Figure 2 (C). Similarly, the hot spot gradually moves from the power supply side end to the non-power supply side end. I'm moving (.

Based on such a wear mechanism, research has been carried out on a method of estimating the position of a hot spot from the voltage Vf across the filament during a cathode cycle and determining the state of wear of the electrode material. In other words, in the state shown in Fig. 2(a), the filament voltage Vt during the cathode cycle becomes the voltage drop Vfl between the connection part of the filament F and the hot spot P, and the voltage drop Vfl in the cathode cycle is as shown in Fig. 2(bJ, (C)). Similarly, in the case of the state shown in FIG. In this way, the lamp life is determined by estimating the remaining amount of electrode material, but conventionally, the magnitude of the cathode voltage Vf is detected as described above to estimate the remaining amount of electrode material. However, in such cases, there were the following meltdowns.

■ During the 8-hour filament preheating period when starting the lamp,
Regardless of the remaining amount of electrode material, the cathode voltage vf increases, indicating malfunction.

■ The electrode filament of the lamp varies depending on the type of lamp and manufacturer, making delicate control difficult.

(Object of the Invention) The present invention has been made in view of the above-mentioned problems, and its purpose is to provide a method for determining the lifespan of a discharge lamp, which can estimate the lifespan at a true price regardless of the lamp type or manufacturer. It is on offer.

(Disclosure of the Invention) The present invention detects the positive/negative asymmetry of the voltage across the filament during lighting, and determines that the life of the lamp has come to an end when the voltage across the filament becomes symmetrical.

The details of the present invention will be explained below. Figure 6 shows the waveform of the voltage Vf across the electrode filament of a discharge lamp such as a fluorescent lamp, and shows how the voltage waveform changes from the initial lighting state of AL through the state of (b) (towards the life of CJ). It shows.

As is clear from the figure, the voltage of the cathode cycle is (a)
It can be seen that while the voltage gradually increases from ~(C), the voltage of the anode cycle hardly changes. The present invention focuses on the positive/negative asymmetry of the voltage across the filament.

Figure 4 shows the configuration of a lamp life determination device using the present invention.
1. In the well-known configuration consisting of power supply AC, lighting circuit B1, fluorescent lamp FL, and starter S, 1. Filament voltage across the filament Vf
The circuit J for detecting the positive/negative asymmetry of
A display circuit is connected to both ends of the filament F of L, and a display circuit is connected to the detection circuit J.

Q is connected.

Next, the operation of the above device will be described. Voltage across filament V
(As mentioned above, only the negative voltage increases as the lighting time elapses, and the positive voltage remains almost constant.The above detection circuit J detects the difference between the positive and negative voltages and operates the display circuit.) Since the asymmetry of the voltage across the filament is detected, it is not affected by the high voltage during the preheating period at startup or the voltage difference between different types of filaments, unlike conventional methods, and therefore accurate life judgment can be performed. be able to.

FIG. 5 shows an example of a specific circuit configuration of the above-mentioned lamp life determination device. A resistor R1 and a capacitor C constitute an integrating circuit, detect the difference in the DC component of the voltage Vi across the filament, and connect the resistor R2 and light emit light. It is connected to a display circuit q consisting of a diode D. - In this case, the voltage vc of capacitor C and e.g.
By setting the circuit constants of the detection circuit J and the display circuit Q so that the voltage levels as shown in FIGS. The lamp life can be notified by keeping the light emitting diode D (directed to the operating voltage) on until the end of its life and turning it off just before the end of its life. Furthermore, if a light emitting diode D whose color changes depending on its operating current is used, more detailed life data can be provided.

(Effects of the Invention) As described above, the present invention detects the positive/negative asymmetry of the voltage across the electrode filament of a discharge lamp during lighting, and determines the end of the life when the voltage between the ends becomes symmetrical. Therefore, the lamp life can be determined accurately without being affected by the high voltage during the preheating period at the time of starting lighting, the voltage difference between different types of filaments, etc.

[Brief explanation of drawings]

Figure 1 is a diagram of a conventional fluorescent lamp lighting circuit, Figure 2 is a diagram explaining the wear mechanism of the electrode material in the lighting circuit, Figure 3 is a voltage waveform diagram across the electrode filament of a discharge lamp, and Figure 4 is a diagram of the current lighting circuit. Lamp life patent applicant using the invention Patent attorney representing Matsushita Electric Works Toshimaru Takemoto (two idiots) Figures 1 and 2 (a) Figure 3 (a) City, (() Figure 4

Claims (1)

[Claims] (1) A method for determining the lifespan of a discharge lamp, which detects the positive/negative asymmetry of the voltage across the electrode filament of the discharge lamp during lighting, and determines the end of the lifespan when the voltages at both ends become symmetrical. .