JPS5960896A - Device for dimming 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] The present invention relates to a discharge lamp dimming device.

Conventionally, in this type of appliance, there are two methods for controlling light: one method uses phase control and the other method uses frequency variation. first,
When phase control is used, flickering due to power fluctuations is likely to occur, making deep dimming impossible. Further, in dimming by variable frequency, there is a series resonance region between L and C in the phase-advancing ballast, and this becomes an overcurrent region, making coupled dimming difficult.

The present invention was made in view of these points, and
It is an object of the present invention to provide a discharge lamp dimming device that can perform continuous dimming in a stable state within a range of about 25%.

This is a description of one embodiment of the present invention based on the drawings. First, a rectifier circuit (2), an inverter (3), a filter (4), a phase advance type ballast (5), and a lamp (6) as a discharge lamp are connected in series to a power source (1). On the other hand, a variable power supply (1) is provided, i.e. an oscillator (7) labeled 3f that emits the third harmonic with respect to the power supply frequency.
is provided, and the oscillator (7) is connected to the input side of the adder (9) via a variable resistor (8) labeled VR. The oscillator (7) is connected to a frequency divider (11), which divides the frequency by ``/3'' and then outputs a predetermined period to the oscillator a indicated as 1f by the delay circuit α. A trigger is applied in a delayed state.A variable resistor (2) labeled VR is connected to this delay circuit α, and by adjusting this variable resistor (to), the phase of the third harmonic can be adjusted. 0.11～
Advance within the range of 0.18π. The oscillator α is VR
, is connected to the adder (9) via a variable resistor CI4 labeled as . A control circuit αQ is connected to this adder (9) via a variable resistor α→ denoted as VR3, and the PWM control circuit αQ is connected to an inverter (3).

As shown in FIG. 2, what is input to the adder (9) is the third harmonic 3f and the fundamental frequency 11 which is equivalent to the power supply frequency, and they have a phase difference of φ.

The waveforms superimposed in this way are shown in Figure 3 (as shown in -1), the PWM control circuit αQ, the inverter (3), the filter (4), the phase-leading ballast (5), and then the lamp (6).
The lamp current flowing through the lamp is as shown in Figure 3 (south). In this waveform, a small discharge occurs in the front portion α, and a main discharge occurs in the rear portion β. Therefore, deep dimming Since there is a slight discharge section even at times, restriking is easy (1), and by superimposing the third harmonic on the fundamental frequency, it is possible to obtain something suitable for deep dimming.

Next, to actually dim the lamp (6), first adjust the variable resistor (6) of the delay circuit so that the phase of the third harmonic 3f with respect to the fundamental frequency 1f is 0.11 to 0. Advance to 18π. Then, by adjusting the variable resistor (8) α to set the fundamental frequency 11 component to 100%, the third harmonic component is set between 20 and 60%. After that, variable resistance α0
Then, set the output voltage to the rated input voltage of the phase advance type ballast (5). In the above state, the lamp (6) lights up in a dimming state based on the setting conditions, but after that, the content rate of the fundamental frequency 11 with respect to the υ third harmonic 3f is changed by adjusting the variable resistor α◆. Depending on the lighting conditions, dimming of 9.90 to 25% is achieved.

Now, FIG. 4 shows how the filament voltage Vf and specific luminous flux Rf change when the phase difference is changed.

Here, when the phase difference φ becomes 0.11π or less, the dimming limit becomes 50% or more, and the phase advance type ballast (5)
There is a possibility of overcurrent at the rated voltage. Furthermore, when the amount exceeds 0.18 g, a significant decrease in filament voltage V/ occurs. From this, the phase difference φ is 0
．． It is necessary to set it in the range of 11 to 0.18π. In addition, in the case shown in FIG. 4, the content rate of the third harmonic 3f is 3.
This is the case of 0%.

Next, what is shown in FIGS. 5 to 7 is the content rate of the third harmonic 3f, the filament voltage V/, and the specific luminous flux R when the phase difference φ is 0.11 g, 0.12 x, and 0.13 w. / shows the relationship between each. These three examples also show that when the third harmonic 3f is less than 20%, the filament voltage V/ decreases and the life of the lamp (6) is shortened, and when it is more than 60%, as estimated from Fig. 7. It is not preferable that the optical output is about 70π at the rated voltage. Therefore, the third harmonic component needs to be in the range of 20 to 60%.

As described above, the present invention converts the third harmonic component to zero at the fundamental frequency.
．． By adjusting the weight in the range of 20 to 60% while advancing the phase by 11 to 0.18π, the light is dimmed by changing the content of the fundamental frequency with respect to the third harmonic component, so the filament voltage does not drop significantly and is stable. It is possible to continuously control the light over a wide range of 90 to 25% in the same state.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a circuit diagram, FIG. 2 is a waveform diagram of waveforms to be superimposed, and FIG. 3 (al.
t+1 is a waveform diagram of voltage and lamp current in a superimposed state, Figure 4 is a graph showing the relationship between phase difference, filament voltage, and specific luminous flux, and Figures 5 to 7 are the content of the third harmonic component. It is a graph which shows the relationship between filament voltage, and specific luminous flux. 1a... Variable power supply, 5... Leading phase ballast, 6...
Lamp (discharge lamp) Applicant: Toshiba Electric Materials Corporation

Claims (1)

[Claims] The variable power source includes a variable power source, a discharge lamp energized by the variable power source, and a phase advance type ballast interposed between the variable power source and the discharge lamp, and the variable power source has a fundamental frequency component and a discharge lamp energized by the variable power source. A discharge lamp dimmer comprising a third harmonic component having a phase difference of 0.11 to 0.18π, the ratio of the third harmonic component to the fundamental frequency component being variable.