JPH01289098A - Light adjusting type electric discharge lamp lighting device - Google Patents

Abstract

PURPOSE:To improve the starting property of the title electric discharge lamp lighting device by adding a back electromotive voltage generated in the loop of primary coils of an inverter output transformer to a supply voltage, rectifying the summation result voltage, applying the rectified voltage via a high-resistance auxiliary current limiting resistor to an electric discharge lamp to cause a very small electric discharge, and meanwhile adding thereto, this DC voltage and a main electric discharge induction voltage generated in the secondary coil. CONSTITUTION:A back electromotive voltage generated in the primary coils 3P1, 3P2 of an output transformer 3 turns into a high pulse voltage when a switching transistor 2 is changed from its turn-on to its turn-off, and the voltage is rectified through a diode 7 to be charged into a capacitor 4a which produces a smoothed DC voltage VH. The DC voltage VH is then charged into a capacitor 4b via a resistor 8, while being applied between electrodes 10a, 10b of an electric discharge lamp 10. The time of time constant for the resistor 8 and the capacitor 4b is longer by one hundred times than the cycle of a pulse oscillated from a pulse width modulation oscillator circuit 1, so that a DC voltage generated between the electrodes of the electric discharge lamp 10 increases gradually until the electric discharge is initiated. Meanwhile, a voltage generated in the secondary coils 3SI of the output transformer 3 is added to a voltage of the capacitor 4b, and the summation result voltage is applied between the electrodes of the electric discharge lamp 10 so that the lamp can be transferred to its normal electric discharge even in an insufficient preheating condition at this moment.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] A dimmable type that is suitable for use in lighting equipment in general that includes a dimming light source with stable color rendering properties, and in particular for lighting equipment used in drafting, learning, reading, and nursery rooms. The present invention relates to a discharge lamp lighting device.

[Purpose of the invention]

In the output circuit of a dimmable discharge lamp lighting device using a pulse width modulation inverter, we have developed a dimmable discharge lamp lighting device that has good start-up performance, wide dimming performance, and high efficiency even at low temperatures. The purpose is to provide.

[Summary of the invention]

In the output circuit of a dimmable discharge lamp lighting device using a pulse width modulation inverter, a high DC voltage is generated from the circuit.
A DC bias is applied to the capacitor and the discharge lamp, and this bias voltage and the output winding voltage are added to provide a high-voltage pulse at startup and power to maintain the discharge at dimming. The device constitutes a means for controlling the temperature using a negative feedback circuit including a parallel resonant circuit, and the synergistic effect thereof enables improvements in dimming characteristics, start-up performance, and efficiency.

[Conventional technology and issues]

The dimmer of the lighting device using the commercial power frequency has 0 advantages.
~100% dimming is possible, but its disadvantages are that it requires a dedicated discharge lamp, ballast, and dimmer, is heavy, bulky, non-versatile, expensive, and has dynamic characteristics such as noise and flicker.
This is excluded from this section as an issue.

Although inverter-based lighting circuits have almost eliminated the drawbacks of the above-mentioned commercial power supply lighting devices, the current level of dimming is about two stages.It is impossible to linearly control discharge lamps with non-linear elements using voltage control. However, if normal discharge is always possible when the current is turned on, pulse width control changes the average value of the discharge current and dimming becomes possible.However, with hot cathode discharge lamps, when the current is low, the internal power loss decreases and the temperature decreases, causing the metal This causes the ions to lose their activity, making it impossible to sustain the discharge.

The present invention is an embodiment of a dimming discharge lamp lighting circuit that solves the above problems and takes advantage of the advantages of an inverter system.

[Example of the present invention]

Figure 1 is a circuit diagram showing an embodiment of the present invention, and Figures 2 and 3 are circuit diagrams showing an embodiment of the present invention.
The figure is a voltage waveform diagram during operation. When a DC voltage VD is applied, the pulse width modulation oscillation circuit 1 is activated, thereby turning the driven switching element 2 on and off, causing an intermittent current to flow through the primary winding of the output transformer 3, and an induced voltage is generated in each winding.

b) When the switch element 2 changes from on to off, the back electromotive force generated in the primary windings 3P1 and 3P2 of the output transformer 3 becomes a high pulse voltage, which is rectified by the diode 7, charges the capacitor 4a, and is smoothed. A DC voltage VH is generated, which charges the capacitor 4b via the resistor 8, and is applied between the electrodes 10a and 10b of the discharge lamp 10. The time constant of the resistor 8 and the capacitor 4b corresponds to the oscillation pulse of the pulse width modulation oscillation circuit l. The DC voltage between the electrodes of the discharge lamp 10 gradually increases until the start of discharge.On the other hand, the voltage generated in the secondary winding 3S1 of the output transformer 3 becomes a high pulse voltage at the time of startup, and increases the voltage of the already charged capacitor. 4b
is added to the voltage and applied between the electrodes of the discharge lamp 1o,
At this time, even if the preheating is insufficient, the discharge lamp 10 causes local destructive discharge and shifts to Townsend discharge, glow discharge, and normal discharge (glow discharge plus arc discharge). .8 seconds.

Ex) The discharge current Il of the discharge lamp 10 that has transitioned to normal discharge is:
At the maximum light intensity during dimming, the voltage VC of the parallel resonant circuit 6 excited to 11 also becomes maximum, and this VC is transferred to the output transformer 3.
Voltage of the secondary winding 3S2 ■ When the voltage of the secondary winding 3S2 is made close to S2 and the same voltage, the primary winding voltage VfL of the flight transformer 5 and the current 1fl become the minimum, and the discharge lamp filament heating current If2
At startup and at low light levels, If is at its minimum and VC is also at its minimum, so the difference between VS2 and VC is large (as a result, If2 also increases, and therefore, at medium light levels, If2 also becomes an intermediate value). In this case, select VS2 and CSQ to obtain a current value that matches the characteristics of the discharge lamp.■
The correlation between β and If2 is not a simple inversely proportional relationship but a non-linear negative feedback loop, but it becomes a temperature control circuit for the discharge lamp filament and plays an important role during startup and dimming, and the configuration of this circuit. High reliability is achieved because the elements are composed only of passive elements.

c) The dimming type discharge lighting circuit using the pulse width modulation method can transmit arbitrary power to the output circuit by changing the pulse width, and at high output, it shifts to normal lighting.At this time, the discharge lamp 10
The electrical characteristics of is a nonlinear negative resistance element that has its own residual voltage.In a series resonant circuit containing a discharging discharge lamp, the Q is apparently higher than that of a resistor with the same loss. This action is reversely induced into the primary winding 3P1 via the secondary winding 3S1 from the series resonant circuit of the inductance of the winding 3S1 of the output transformer 3, the capacitor 4b, and the discharge lamp, and is superimposed on the power supply voltage VD, causing the switch An inverter circuit with low switch element loss reduces the voltage ■ SW applied to this element when it turns on and off, reduces loss in switch element 2, and suppresses temperature rise. In this example, it is 150KH.
2(7) It is an inverter, making it possible to downsize the output transformer and other parts.

〔Effect of the invention〕

As explained in the examples above, the back electromotive voltage of the primary winding of the output transformer of the inverter is added to the power supply voltage, rectified, and applied to the discharge lamp via the high-resistance auxiliary current-limiting resistor to generate a minute discharge. Furthermore, this DC voltage is added to the voltage for main discharge of the secondary winding, and the transition to normal discharge occurs even at startup and with a narrow pulse current.

(1) The temperature of the discharge lamp filament is controlled by the interaction between the negative feedback circuit and the parallel resonant circuit.The synergistic effect of (a) and (b) and the action of c) in the example improve dimming performance, start-up performance, and efficiency. An improved dimmable discharge lamp lighting device is obtained.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is a circuit diagram showing an embodiment of the present invention.
Figure 3 is a diagram of the voltage waveform applied to both ends of the discharge lamp at maximum output in this example, and Figure 4 is a diagram of the voltage waveform applied to both ends of the discharge lamp at low output in this example. The connection diagram of the dimmer and ballast when the commercial power source is turned on is shown. 2: Switch element, 3: Output transformer, 3S1: Secondary winding that supplies the main discharge current to the discharge lamp, 3S2: Secondary winding for filament current supply, 4a: High frequency smoothing capacitor, 4b: Series with current limiter Resonance, dual-purpose capacitor, 5: filament transformer, 6: parallel resonant circuit for control, 7: diode for back electromotive pulse rectification, 8: high resistance that applies DC voltage to 4b and 4b, 10: discharge lamp. Patent applicant Shigeharu Noguchi Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] A dimmable discharge lamp lighting device based on a pulse width modulation inverter includes a switch element that turns on and off the direct current of a primary winding of an output transformer that supplies power to the discharge lamp, and a switch element connected in series with the primary winding. A direct current voltage obtained by rectifying and smoothing the back electromotive force of the step-up winding is applied to the discharge lamp through a resistor to apply an electric field and charge a first capacitor, and the capacitor supplies a main discharge current of the discharge lamp. the first of the output transformer
The primary winding of the filament transformer is connected in series to the node of L and C of the parallel resonant circuit excited by the discharge current, and the second secondary winding of the output transformer is connected to both ends of the series circuit. A dimmable discharge lamp lighting device based on a pulse width modulation inverter connected to a secondary winding, and the plurality of secondary windings of the filament transformer supplying current for temperature control to each discharge lamp.