JPH01166496A - Dimmer device for electric discharge lamp - Google Patents

Abstract

PURPOSE:To prevent the illuminance of an electric discharge lamp from fluctuation by starting the discharge of the electric discharge lamp at a small phase angle and changing the discharge to dimmer at a small phase angle upon the start of lighting. CONSTITUTION:There are provided a phase control circuit 9 for making the phase- control of output of a power supply 8 for supplying power to the side of a stabilizer 7, and an a.c. machine 10 as a current detecting means for detecting an increment change in load current at the time of lighting start of a fluorescent lamp 6. Also, there is provided a phase angle switching circuit 11 for switching a phase angle set up in the phase angle control circuit 9 upon receipt of a detected signal to the predetermined and desired dimmer phase angle phi2 larger than a phase angle phi1 before a lighting start. And an electric power is supplied under a dimmer condition at the smaller phase angle phi1 during a time from the turning-on of the power supply 8 to the lighting start of the fluorescent lamp 6 via preheating. Upon the lighting start of the fluorescent lamp 6, a dimmer condition at the larger phase angle phi2 is selected and an electric power is supplied. According to the aforesaid construction, it is possible to apply voltage high enough for lighting to a load at the time of a dimmer start, and the illuminance of the electric discharge lamp is free from fluctuation before and after a dimmer start.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a dimmer for a discharge lamp, and more particularly, to a dimmer for a discharge lamp.
The present invention relates to a discharge lamp dimmer that uses a discharge lamp as a load and adjusts the light output of the discharge lamp through phase control.

BACKGROUND ART Discharge lamp dimmers using phase control have been known for a long time. FIG. 6 is a circuit diagram showing a conventional example of the discharge lamp dimmer. A two-wire output type dimmer 4 is inserted in the middle of a power supply path connecting the ballast 2 and the power source 3.

The power supply to the load is adjusted by phase control using the dimmer 4, thereby adjusting the light output of the discharge lamp 1. In this case, a high-frequency inverter ballast consisting of an electronic circuit is used as the ballast 2 for lighting the discharge lamp 1, and a high-voltage pulse for starting the lamp is constantly superimposed on the secondary side of the ballast 2. Even during dimming at low illuminance where the input voltage to the load is low, the voltage is high enough to sufficiently light a general internal stripe type fluorescent lamp, which is a discharge lamp.

However, increasing the secondary voltage of the ballast 2 as described above is nothing but increasing the stress applied to the discharge electrode that also serves as a preheating filament of the discharge lamp 1 when the discharge lamp 1 is started. Furthermore, during dimming, sufficient preheating may not be possible due to a decrease in the filament preheating voltage.

Generally, these are considered to be the causes of shortening the life of the discharge lamp 1.

Therefore, in order to reduce the stress on the discharge electrodes when starting the discharge lamp 1 (including when starting dimming),
Various techniques have been tried in the past, and a typical example is a dimmer device in which a dimmer has a built-in timer.

FIG. 7 is a waveform diagram showing the output voltage from the dimmer to the discharge lamp in the case of this dimmer. This dimmer uses a timer to prevent phase control for a certain period of time after the power is turned on. For example, the dimmer's phase control
% light output, as shown in Figure 7, after the power is turned on, preheating, starting, and lighting are performed under the dimming conditions of 100% light output, and after a few seconds the timer starts. When the time limit is reached, phase control is initiated and the light output is reduced to the desired value of 50%. Therefore, in the case of this dimmer, it is possible to apply a high voltage sufficient for lighting to the load at the time of starting dimming, and also to
There is no need to make the next voltage higher than necessary, so discharge lamp 1
There is no increase in stress on the discharge electrode.

Purpose However, in the case of the above-mentioned dimmer device, in order to ensure dimming start, it is necessary to set the timer's time limit to be slightly longer than the time from when the power is turned on until the discharge lamp 1 starts. Therefore, the illuminance changes significantly between the time when the discharge lamp 1 is at 100% light output from when it starts until it starts dimming, and after it starts dimming, making the user feel uncomfortable. . This is a big problem, especially in the case of stage lighting.

An object of the present invention is to provide a dimmer for a discharge lamp, which is capable of applying a voltage high enough for lighting to the load at the time of dimming start, and which prevents the illuminance of the discharge lamp from changing before and after the dimming start. The goal is to provide the following.

Embodiment FIG. 1 is a circuit diagram showing a discharge lamp dimming device 5 according to an embodiment of the present invention. The discharge lamp dimmer 5 is connected in the middle of a power supply path that connects an alternating current power supply 8 to a fluorescent lamp 6 and a ballast 7 as a discharge lamp, which are loads thereof. This discharge lamp dimmer 5 includes a phase control circuit 9 that controls the phase of the output of a power source 8 and supplies it to the ballast 7 side, and a phase control circuit 9 that detects an increase in the load current when the fluorescent lamp 6 starts lighting. An alternator (abbreviated as CT) 10 serving as a current detection means and a phase angle set in the phase control circuit 9 in response to a detection signal output from the alternator 10 are dimmed to a value larger than the phase angle ψ1 before the start of lighting. and a phase angle switching circuit 11 for switching to a predetermined desired phase angle ψ2.

The phase control circuit 9 has a triac 13 inserted in series with a high-frequency blocking coil 12 in the middle of a power supply path connecting the power source 8 and the ballast 7, and has a triac 13 inserted in series with a high frequency blocking coil 12, and has a triac 13 connected to the high frequency blocking coil 12 in series. By applying a trigger, the triac 13 is configured to conduct at a phase angle corresponding to the trigger generation timing. In addition, the trigger generation circuit 14
Here, the trigger generation timing is determined by the zero cross signal from the power supply synchronous pulse generation circuit 15 that detects the zero zero point of the output of the power supply 8 and the output signal from the charging/discharging circuit 16. A fader voltage generation circuit 17 is connected to the charging/discharging circuit 16, and is configured such that the trigger generation timing, that is, the phase angle of the phase control, can be variably set by this circuit 16. The charging/discharging circuit 16 and the fader voltage generation circuit 17 are supplied with a power supply voltage from a power supply line through a transformer 18, a rectifier circuit 19, and a smoothing capacitor 20.
A voltage that has been rectified and smoothed is applied.

In the phase angle switching circuit 11, the output signal from the alternator 10, which outputs the change in the input current to the ballast 7 in the form of voltage, is rectified and smoothed by a rectification/smoothing circuit 23 consisting of a diode 21 and a capacitor 22, and further After differential processing is performed by a differentiating circuit 26 consisting of a capacitor 24 and a resistor 25, the voltage between the terminals of the Zener diode 27 is taken out, and this is applied to the terminals of the J-K flip-flop 28 which operates as shown in the truth table shown in Table 1. Input to CK.

The output of the rectifier/smoothing circuit 23 in Table 1 is expressed by the resistor 29 and capacitor 3.
0 and a Schmitt trigger circuit 32, and then input to the CLR terminal of the flip-flop 28 mentioned above. Then, according to the output signal outputted from the terminal Q of the flip-flop 28 to this J-, the output of the charging/discharging circuit 16 is switched from the output corresponding to the small phase angle ψ1 to the output corresponding to the large phase angle ψ2. It is configured.

FIG. 2 shows the above-mentioned trigger generation circuit 14 and charge/discharge circuit 1.
6 is a circuit diagram showing an example of a specific configuration of the fader voltage generating circuit 6 and the fader voltage generating circuit 17. FIG. The trigger generation circuit 14 has P U
T (Programmable tlnijunc
tionTransistor) 33, resistance 34~
37, it is composed of a photocoupler 38 and a transistor 39 that provide a signal to the gate of the triac 13.

The charging/discharging circuit 16 is composed of a variable resistor 40, a capacitor 41, and diodes 42 and 43. The fader voltage generation circuit 17 is composed of a variable resistor 44.

The output signal from the terminal Q of the flip-flop 28 is input to the connection point between the variable resistor 44 and the diode 42 via the inverter 45 and the diode 46.

FIG. 3 is a circuit diagram showing another example of a specific configuration of the trigger generation circuit 14 and charge/discharge circuit 16 described above. The trigger generation circuit 14 has the same configuration as that shown in FIG. In this case, the charging/discharging circuit 16 includes, in addition to a variable resistor 40 and a capacitor 41, another capacitor 47 and a triac 48 connected in parallel. The signal is input to the gate of the triac 48 via a resistor 49. Note that the fader voltage generation circuit 17 is omitted in this circuit.

Next, the dimming operation of the fluorescent lamp 6 by the discharge lamp dimming device 5 described above will be explained with reference to the timing chart shown in FIG. 4 and the dimmer output waveform diagram shown in FIG. 1st
When the power supply switch 50 of the power supply path in the figure is turned on to turn on the power, power is supplied from the power supply 8 to the ballast 7 side through the coil 12 and the triac 13, and from the alternator 10, the load current changes at this time. is shown in Figure 4 (1)
It is extracted by converting it into the voltage shown in the waveform diagram. alternator 1
The output of 0 is the diode 21 of the next rectifier/smoothing circuit 23.
The signal is half-wave rectified as shown in FIG. 4(2), and further smoothed by the capacitor 22 as shown in FIG. 4(3).

The smoothed waveform is further processed into a fourth differential circuit 26 at the next stage.
It is converted into a differential waveform as shown in Figure (4). Since the above-mentioned load current has a large change when the power is turned on and when the fluorescent lamp 6 starts lighting, the differential waveform has a peak at the time when the power is turned on and when the lighting starts. This peak voltage is higher than the breakdown voltage of the Zener diode 27 at the next stage of the differentiating circuit 26, and therefore the voltage of the J-K flip-flop 28 is
The breakdown voltage of the Zener diode 27 is input to the K terminal as an H level signal. On the other hand, the rectification/smoothing circuit 23
The smoothed waveform output from the above is converted into a delayed pulse waveform that rises a little later than when the power is turned on, as shown in Fig. 4 (5), through delay processing by an integrator circuit 31 with a large time constant and a Schmitt trigger circuit 32. This is input to the CLr (terminal) of the flip-flop 28 to J-.
Since the flip-flop 28 operates as shown in the truth table in Table 1, the rising edge of the delayed pulse waveform input to the CLR terminal (slightly later than when the power is turned on)
Then, the output waveform of the terminal Q rises as shown in FIG. 4 (6). On the other hand, when a high-level signal is input to the terminal CK at the time when the next lighting starts, the output waveform of the terminal Q falls, and the output waveform of the terminal Q will change from then on until the input signal from the CLR terminal becomes low level. It is held at a high level as long as possible, that is, unless the power switch 50 is turned off.

The operation of the phase control circuit 9 will be explained below with reference to the specific example shown in FIG. After the power is turned on and until the fluorescent lamp 6 starts lighting, the Q terminal output of the flip-flop 28 is at a low level as described above, so the output is applied to the fader voltage generation circuit 17 via the inverter 45 and the diode 46. A high level signal is applied to the variable resistor 44. Therefore, the output voltage of the charge/discharge circuit 16 is increased by that amount, and the PU of the trigger generation circuit 14 is
The timing at which T33 turns on is accelerated. Along with this, the series of operation timings such as "transistor 39 is turned on" → "light-emitting diode 38a of photocoupler 38 is conductive" → "light-emitting diode 38b of photocoupler 38 is conductive" is accelerated, and the phase for turning on the triac 13 is accelerated. The corners become smaller.

However, when the lighting starts, the Qt output of the flip-flop 28 is reversed to high level, so 1.
A high level signal is no longer applied from the path of the inverter 45 and the diode 46 to the variable resistor 44 constituting the fader voltage generation circuit 17, and the output voltage of the charge/discharge circuit 16 becomes lower than before, turning on the PUT 33. As the timing is delayed and the phase angle for turning on the triac 13 becomes large, the operation of 0 or more causes the fluorescent lamp 6 to be preheated before the power is turned on, as shown in Figure 5, which shows the output voltage waveform from the discharge lamp dimmer 5. Until the fluorescent lamp 6 starts lighting, power is supplied under dimming conditions with a small phase angle ψ1 (here ψ=0°), and as soon as the fluorescent lamp 6 starts lighting, it changes to a large phase angle ψ2 (here In this case, power is supplied by switching the dimming conditions (9'2=90°). In addition, the second
In the circuit shown in the figure, by variably setting the resistance value of the variable resistor 44 that constitutes the fader voltage generation circuit 15,
The phase angle after the start of lighting, in other words, the dimming rate can be freely changed.

In addition, in the case of the circuit shown in FIG. 3, until the lighting starts, the Q terminal output of the flip-flop 28 is at a low level at J-, so the triac 48 is not turned on, and the capacitance component of the charge/discharge circuit 16 is two capacitors connected in series 4
1.47, the time constant becomes smaller, the timing at which the PUT 33 of the trigger generation circuit 14 is turned on is earlier, and the phase angle of the phase control becomes smaller. On the other hand, when the lighting starts, the flip-flop 2 is connected to J-.
When the output of terminal Q of 8 becomes high level, the triac 48 turns on and conducts between both terminals of the capacitor 47 of the charging/discharging circuit 16, so the time constant of the charging/discharging circuit 16 becomes larger and the trigger becomes more active than before. PUT33 of generation circuit 14
The timing of turning on is delayed and the phase angle of phase control becomes large.

Effects As described above, according to the discharge lamp dimmer of the present invention, discharge of the discharge lamp is started at a small phase angle at which a high enough voltage for lighting is applied to the load. Not only can the lamp be turned on, but it also switches to dimming with a large phase angle as soon as it starts lighting, so there is no change in the illuminance of the discharge lamp! This has the effect of not giving the RQ user a sense of discomfort.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a discharge lamp dimmer 5 according to an embodiment of the present invention, and FIG. 2 shows a trigger generation circuit 14 and a charging/discharging circuit 16.
FIG. 3 is a circuit diagram showing another example of the specific structure of the trigger generation circuit 14 and the charging/discharging circuit 16, and FIG. 4 is a circuit diagram showing an example of the specific structure of the fader voltage generation circuit 17. 5 is a waveform diagram showing the output voltage from the discharge lamp dimmer 5, FIG. 6 is a circuit diagram showing the conventional discharge lamp dimmer, and FIG. FIG. 7 is a waveform diagram showing the output voltage from a dimming device using still another conventional discharge lamp dimming method. 5... Discharge lamp dimmer, 6... Fluorescent lamp, 7... Ballast, 9... Phase control circuit, 10... AC generator, 11
...Phase angle switching circuit, 12... Coil, 13...
Triac, 14...Trigger generation circuit, 15...
Power supply synchronization pulse generator circuit, 16...Charging/discharging circuit, 23
... Rectifier/smoothing circuit, 26... Differential circuit, 28...
・Flip-flop on J-, 31...Integrator circuit agent Patent attorney Number of strokes Keiichi No. 2 Figure M3 Figure 5 Figure 6 Figure 7

Claims (1)

[Scope of Claim] A discharge lamp dimmer that uses a discharge lamp as a load and adjusts the light output of the discharge lamp by phase control, which uses a large amount of electric power to start lighting the discharge lamp, and A current detecting means for detecting an increase in load current as the lamp starts lighting; and a means for adjusting the phase angle to a desired value in response to a detection signal from the current detecting means. A dimmer device for a discharge lamp characterized by the following.