JP2514644B2 - Discharge lamp lighting device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a discharge lamp lighting device.

BACKGROUND ART FIG. 6 shows a schematic configuration of a discharge lamp lighting device using a conventional high-frequency inverter. This discharge lamp lighting device is a DC power supply E (it is also possible to rectify and smooth the AC power supply)
Is connected in parallel with _two transistors Q ₁ and Q ₂ which are switching elements connected in series, and a load circuit including a discharge lamp LA is connected in parallel with one transistor Q ₁ via a capacitor C _1. and, transistor Q _1, Q ₂
Is alternately switched by the outputs from the two windings n ₁₂ and n ₁₃ of the drive transformer T ₁ to supply power to the load circuit.

When the power switch SW ₁ is turned on, the starting circuit ST applies a pulse current to the base of the transistor Q ₂ to start oscillation. Here, the starting circuit ST is composed of a resistor R ₁ , a capacitor C ₃ , and a diac Q ₅ . Further transistor Q ₂
Between the base and emitter of which is connected to the sub-transistors Q _3, its on, off control, the lamp current primary winding n ₂₁
This is performed by the output signal of the secondary winding n ₂₂ of the detection transformer T ₂ which is detected by flowing the current to the detector. The switch SW ₃ is a dimming switch, and the switch SW ₃ is closed during dimming. Further, when the switch SW ₃ is closed, that is, when dimming, the ON signal of the sub-transistor Q ₃ determines the winding method of the detection transformer T ₂ so as to be obtained while the transistor Q ₂ is on. Therefore, during dimming, the ON period of the transistor Q ₂ becomes shorter than the ON period of the transistor Q ₁ . FIG. 7 shows this digitally. Figure 7 (a) transistors Q _1, Q ₂ of the on-period at full lighting of the dimming switch SW ₃ off, FIG. (B) transistors are dimming switch SW ₃ at ON dimming Indicates the ON period of Q ₁ and Q ₂ . As described above, in this circuit, the direct current component is cut by the capacitor C ₁ by unbalancing the ON periods of the main transistors Q ₁ and Q ₂ , and the discharge lamp LA has no direct current component Q ₁ In the same period of Q ₂ , a smaller current flows than the current flowing in the discharge lamp LA when it is on.

However, in the above conventional example, when the discharge lamp LA is a discharge lamp that requires preheating such as a fluorescent lamp, the following problems occur. In general, in the case of a fluorescent lamp or the like that requires preheating, it is preferable to apply a high voltage to the discharge lamp LA after the preceding preheating due to problems such as lamp life. In the case of a fluorescent lamp that requires preheating as in the conventional example of FIG. 6, the timer circuit TM closes the preheating switch SW ₂ for a certain period of time after power-on, and then opens it, regardless of the full lighting mode or dimming mode. By discharge lamp LA
Will be turned on.

The circuit will be further described with reference to FIG. 6 circuit. Power switch SW
_{After 1} is turned on, the starter circuit ST starts oscillation and the timer circuit TM closes the preheat switch SW _{2 for} a certain period of time. The current that flows at this time is the positive electrode of the DC power supply E → power switch SW ₁ → capacitor C when the transistor Q ₂ is on.
₁ → discharge lamp LA → one filament → preheat switch SW ₂ →
The other filament of the discharge lamp LA → the primary winding n ₂₁ of the detection transformer T ₂ → the inductance L ₁ → the primary winding n _{11 of the} transformer T _1.
→ Transistor Q ₂ → Flows in the path on the negative side of the DC power supply E. The transistor when Q ₁ is turned on, the capacitor C ₁ of the capacitor C ₁ in a direction to discharge the charged electric charge → transistor Q ₁ → 1 of the drive transformer T ₁ winding n ₁₁ → inductance L
₁ → primary winding n ₂₁ of detection transformer T ₂ → one filament of discharge lamp LA → preheat switch SW ₂ → other filament of discharge lamp LA → current flows through the path of capacitor C ₁ . Therefore, it is considered that the resistance of the filament is always small while the preheating switch SW ₂ is closed, so that almost no current flows in the capacitor C _{2 of the} load circuit. So drive transformer
The current flowing through the primary winding n ₁₁ of T ₁ is equal to the current flowing through the primary winding n ₂₁ of the detection transformer T ₂ (both in phase and magnitude)
Become. During preheating so that in the dimming switch SW ₃ is turned on to have dimming mode, the base of the auxiliary transistor Q ₃ same signals substantially phase based signal of the transistor Q ₂ is input, the sub-transistor Q ₃ By turning on, the transistor Q ₂ turns off quickly. This allows the transistor
Since the ON section of Q ₁ and Q ₂ becomes unbalanced, the preheating current becomes smaller during preheating in the dimming mode (dimming switch SW ₃ is on), similar to when dimming the light. Therefore, in the dimming mode, a sufficient preheating current cannot be obtained, which not only adversely affects the life of the lamp, but also makes starting and lighting difficult. In order to solve this, in the case of dimming lighting, there is also a method of once turning on all the power and then dimming lighting, but there is a problem that the control circuit becomes complicated. The diodes D ₁ and D
Reference numeral ₂ is a protection diode, and windings n ₁₂ and n ₁₃ are secondary windings of the drive transformer T ₁ .

FIG. 8 shows another conventional example. This conventional example circuit detects the lamp current by the detection transformer T ₂ and
Rectifying and smoothing with D ₃ and capacitor C ₄ , comparing this voltage Vk with reference voltage e with comparator IC ₃ (eg μPc451),
This output signal q ₃ turns on the sub-transistor Q ₃ , forcibly turns off the transistor Q _2, and unbalances the on-states of the transistors Q ₁ and Q ₂ to reduce the lamp current and reduce the lamp current. It is designed to be kept constant at all times. However, as shown in the figure, in the case of a fluorescent lamp in which the discharge lamp LA requires preheating, the following problems occur. First, when the power switch SW ₁ is turned on and the DC power source E is turned on, the oscillation is started by the starting circuit ST. At this time, since the preheat switch SW ₂ is closed by the timer circuit TM for preheating, the filament of the discharge lamp LA is preheated. In general, the preheating current is larger than the lamp current during normal lighting, so the detection voltage Vk (pre) detected by the preheating detection transformer T ₂ is larger than the reference voltage e.

Therefore, the level of the output signal q ₃ of the comparator IC ₃ is always high level. At this time, the transistor Q ₄ has a ninth
The signal q ₂ shown in FIG. Then, the transistor Q ₄ is turned off for a while after the transistor Q ₂ is turned on (see FIG. 9B). Since this time-based signal q ₃ sub transistor Q ₃ are at the high level as described above, the sub-transistor Q ₃ is turned on, the main transistor Q ₂ is forcibly turned off. Therefore transistor Q ₁
And the ON section of Q ₂ becomes unbalanced, the DC component is cut by the capacitor C ₁ , and the preheating current is smaller than the preheating current without the DC component when the transistors Q ₁ and Q ₂ are on for the same period. . For this reason, not only the lamp life is adversely affected, but it becomes difficult to start the discharge lamp LA when the temperature is low. To solve this, there are methods such as once stopping the operation of the sub-transistor Q ₃ after turning on the power and forcing the output signal q ₃ of the comparator IC ₃ to the low level, but the control circuit is complicated. become.

As above, the load current is detected by the detection transformer T ₂ ,
When controlling, the current is detected even during the preheating, which may be inconvenient.

The monostable multivibrator IC ₁ , IC ₂ (for example, MC14
538B, SN7123N) operates as follows. That is, at the input terminal B ₁ of the monostable multivibrator IC ₁ , the voltage V _R3 obtained by dividing the V _{CE of the} transistor Q ₂ by the resistors R ₂ and R _3.
(Fig. 9 (a)) is input. At the output terminal Q ₁ of the monostable multivibrator IC ₁ , a signal q ₁ that goes high at the falling edge of the voltage V _R3 is output. This time is determined by the capacitor C ₅ and the resistor R ₄ (see FIG. 9C). Output signals q ₁ of the monostable multivibrator IC ₁ 'is further inputted to the input terminal B ₂ of the monostable multivibrator IC _2, the output terminal ₂ of the monostable multivibrator IC _2, a low level at the falling edge of the signal q ₁ The signal q ₂ is output. The low level period of the signal q ₂ is determined by the capacitor C ₆ and the resistor R ₅ (see FIG. 9 (d)).

This signal q ₂ is input to the base of the transistor Q ₄ via the resistor R ₈ and turns on / off the transistor Q ₄ . The waveform in Fig. 9 (b) shows the current flowing through the transistor Q _2.
Indicates I _Q2 .

[Object of the Invention] The present invention has been made in view of the above problems, and an object of the present invention is to provide a discharge lamp lighting device capable of performing sufficient preheating during preceding preheating.

DISCLOSURE OF THE INVENTION The present invention includes a lighting circuit unit, a preheating unit that preheats a filament of a discharge lamp to be energized by an output of the lighting circuit unit, and a detection transformer that detects a lamp current. In a discharge lamp lighting device provided with a control means for controlling the output of a lighting circuit section by this output, a winding through which a current flows only during preheating is provided in the detection transformer, and the polarity of the winding is set to the lamp current of the detection transformer. It is characterized in that the winding has a polarity opposite to that of the winding for detecting, and no output is generated on the secondary side of the detection transformer during preheating.

FIG. 1 shows a schematic configuration of the present invention. The lighting circuit unit 1 using this AC power source AC as a power source is a half bridge type,
It consists of a high-frequency inverter such as a push-pull method or a normal copper-iron ballast, and a discharge lamp between its secondary output terminals.
LA and primary winding n ₂ of detection transformer T ₂ for lamp current detection
And a series circuit with is connected. Also, at the non-power source side end of both filaments of the discharge lamp LA, a preheat switch SW ₂ and a detection transformer T
A series circuit with _two primary windings n ₁ is connected. The preheat switch SW ₂ is turned off by the timer circuit TM after a fixed time has elapsed since the power was turned on.

The detection transformer T ₂ detects the lamp current by the primary winding n ₂₁ , and the output of the secondary winding n ₂₂ is input to the control unit 2.
The control unit 2 controls the output of the lighting circuit unit 1 according to the magnitude of the secondary output to perform dimming or make the lamp current constant.

Here, in the discharge lamp lighting device of the present invention, currents of the same phase flow in the primary windings n ₂₁ and n ₂₃ of the detection transformer T ₂ during preheating, but as shown in the figure, the primary winding of the detection transformer T ₂ n ₂₁ ,
Since the polarity of n ₂₃ is opposite, no voltage is induced in the secondary winding n ₂₂ , and a sufficient preheating current can be obtained.

 The present invention will be described below with reference to examples.

Example 1 Figure 2 shows the present embodiment, this embodiment detects the transformer T ₂ of the Figure 1 circuit to sense transformer T ₂ of the Figure 6 prior art
The primary winding n ₂₃ corresponding to the primary winding n ₂₃ is added, and the other configuration is the same as that of the circuit in FIG.

Then, when the power switch SW ₁ is turned on, the starter circuit ST causes the transistors Q ₁ and Q _{2 of} the high frequency inverter forming the lighting circuit unit 1 to start oscillating. Since the preheat switch SW ₂ is closed for a certain period of time by the timer circuit TM in conjunction with this power-on, the filament of the discharge lamp LA is preheated. In this case although an in-phase current flows through the primary winding n _21, n ₂₃ of detection transformer T _2, the polarity of each winding n _21, n ₂₃ are reversed polarity, the detection transformer T ₂ wound No voltage is induced on line n ₂₂ . As described above, in this embodiment, when the dimming switch SW ₃ is turned on, that is, during preheating in the dimming mode, no voltage is induced in the secondary winding n ₂₂ of the detection transformer T ₂ , and the subtransistor Q ₃ Does not work. Therefore, the ON sections of the transistors Q ₁ and Q ₂ become equal, and normal preheating is performed.

After fully preheated, preheat switch by timer circuit TM
SW ₂ is opened and the discharge lamp LA lights up. Has a dimming switch SW ₃ as described in the prior art since no current flows in a state the dimming lights If on the primary winding n ₂₃ of detection transformer T ₂ after the lighting.

Embodiment 2 This embodiment corresponds to the conventional example shown in FIG. 8. The detection transformer T ₂ has a primary winding n ₂₃ of the detection transformer T ₂ shown in FIG.
The primary winding n ₂₃ corresponding to the above is provided, and other configurations are similar to the circuit of FIG.

In this embodiment also, since the primary windings n ₂₁ and n ₂₃ have opposite polarities, no output voltage is induced in the secondary winding n ₂₂ during preheating, and normal preheating is performed as in the first embodiment. Done.

Embodiment 3 This embodiment is an embodiment of a two-lamp series lighting circuit as shown in FIG. 4, and includes a primary winding n ₃₁ of the preheating transformer T _{3 and} a primary winding n ₂₃ of the detection transformer T _2. connects the series circuit of the preheating switch SW ₂ to the non-power supply side end of the discharge lamp LA _1, filaments f ₁ at both ends of the LA _2, f _4, the discharge lamp LA _1, filament inside the LA ₂ f _2, The secondary winding n ₃₂ of the preheating transformer T ₃ is connected in parallel to the primary winding n ₂₁ of the detection transformer T ₂ via f ₃ .

Thus, at the time of preheating, the primary windings n ₂₁ , n of the detection transformer T ₂ are
_{Since 23} has the opposite polarity, an output voltage is not induced in the secondary winding n ₂₂ of the detection transformer T ₂ during preheating, and normal preheating is performed as in the first embodiment.

In this embodiment, when _one of the filaments f ₂ and f ₃ inside the discharge lamps LA ₁ and LA ₂ is broken, the filament of the discharge lamp LA ₁
f ₁ → primary winding of preheating transformer T ₃ n ₃₁ → primary winding of detection transformer T ₂ n ₂₃ → preheating switch SW ₂ → current flows through filament f ₄ of discharge lamp LA ₂ and detection transformer T during preheating There is a problem that ₂ detects current.

Embodiment 4 This embodiment solves the problems of Embodiment 3 and
As shown in the figure, the primary winding n ₃₁ of the preheating transformer T ₃ and the preheating switch SW ₂ are directly connected in series, and the filament f ₂ of the discharge lamp LA _{1 and} the primary winding n ₂₁ of the detecting transformer T ₂ are connected. , Filament f ₃ of discharge lamp LA ₂ and secondary winding n of preheating transformer T _3
32, detection transformer T ₂ of the present invention which form a closed circuit of the primary winding n _23, since any filament f ₁ ~f ₄ The dead no current flows through the primary winding n ₂₃ of the detection transformer T ₂ The detection transformer T ₂ does not detect current during preheating.

EFFECTS OF THE INVENTION The present invention is provided with a lighting circuit unit, a preheating unit that preheats the filament of a discharge lamp to be energized by the output of the lighting circuit unit, and a detection transformer that detects a lamp current. In a discharge lamp lighting device provided with a control means for controlling the output of a lighting circuit section by this output, a winding through which a current flows only during preheating is provided in the detection transformer, and the polarity of the winding is set to the lamp current of the detection transformer. Since the polarity is opposite to that of the winding that detects the temperature and the output is not generated on the secondary side of the detection transformer during preheating, the preheating current is detected by the detection transformer during preheating, and the preheating current is reduced by the output control of the lighting circuit section. There is no problem in that it is possible to carry out reliable preheating, the life of the lamp can be extended, and the structure is simple and the manufacturing cost is low.

[Brief description of drawings]

1 is a schematic circuit configuration diagram of the present invention, FIG. 2 is a circuit diagram of a first embodiment of the present invention, FIG. 3 is a circuit diagram of a second embodiment of the present invention,
4 is a circuit configuration diagram of a third embodiment of the present invention, FIG. 5 is a circuit configuration diagram of a fourth embodiment of the present invention, FIG. 6 is a circuit diagram of a conventional example,
FIG. 7 is a time chart for explaining the operation of the above, FIG. 8 is a circuit diagram of another conventional example, and FIG. 9 is a waveform diagram for explaining the operation of the same. 1 ...... lighting circuit unit, 2 ...... control unit, T ₂ ...... detection transformer, LA ...... discharge lamp, n _21, n ₂₃ ...... 1 winding, n ₂₂ ...... 2 winding, SW ₂ ... … Preheat switch, TM… Timer circuit.

Claims (2)

(57) [Claims] 1. A lighting circuit section, preheating means for preliminarily preheating a filament of a discharge lamp to be energized by the output of the lighting circuit section, and a detection transformer for detecting a lamp current are provided. In a discharge lamp lighting device having a control means for controlling the output of a lighting circuit section, a winding through which a current flows only during preheating is provided in the detection transformer, and the polarity of the winding is used to detect the lamp current of the detection transformer. A discharge lamp lighting device characterized in that the polarity is opposite to that of the winding, and no output is generated on the secondary side of the detection transformer during preheating. 2. The discharge lamp lighting device according to claim 1, wherein the lighting circuit section is composed of a high frequency inverter for converting a DC power supply into an AC.