JPH11238588A - Discharge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To light different sorts of discharge lamps of a relatively thin tube size and with different rated outputs roughly as rated, and to reduce the stresses for all the discharge lamps at a end of life period. SOLUTION: When an action frequency (f) of an inverter circuit 1 at the time of starting is set as f1 , constants for choke coils L1 , L2 and capacitors C1 , C2 are set in such a way that a rated starting voltage is applied to a discharge lamp La1 of 10 W at the action frequency f1 , and that a rated starting voltage is applied to the discharge lamp La2 of 6 W. Outputs of both fluorescent lamps La1 , La2 can thus be reduced (or lighted off) when at least either of the fluorescent lamps La1 , La2 approaches its end of life period. The inverter circuit 1 is actuated in the range of the optimum action frequency when the fluorescent lamps La1 , La2 of 10 W and 6 W are lighted, so that the two sorts of the fluorescent lamps La1 , La2 can be lighted in a condition close to their rated characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plurality of types of discharge lamps (particularly fluorescent lamps) having different rated outputs using an inverter circuit.
The present invention relates to a discharge lamp lighting device for starting and lighting a lamp.

[0002]

2. Description of the Related Art Conventionally, as a lighting device for starting and lighting a discharge lamp such as a fluorescent lamp, a DC power obtained by rectifying and smoothing an AC power is supplied to an inverter circuit of about 50 k.
2. Description of the Related Art Discharge lamp lighting devices that convert high-frequency power into high-frequency power and supply the discharge lamp with high-frequency power of about 50 kHz are well known.

It is also well known that fluorescent lamps include types such as a straight tube type fluorescent lamp and a ring type fluorescent lamp, but in recent years, from the viewpoint of energy saving, a fluorescent lamp having a small tube diameter has been used. Hereinafter, it will be called “small tube diameter fluorescent lamp”.) Furthermore, by lighting a high-efficiency thin-tube fluorescent lamp at high frequency, the amount of light output per supply power is increased, and it is attracting attention as environmentally friendly lighting.

[0004] However, in general, a fluorescent lamp requires a very high starting voltage (for example, 500 V or more) at startup when the tube diameter is reduced. The point that a high starting voltage is required as described above is a major problem. In addition,
It is already known that there is a tube diameter of 8 mm and a rated output of 10 W and 6 W as the above-mentioned tube diameter fluorescent lamp. Electric lighting devices have already been commercialized.

FIG. 5 is a circuit diagram showing an example of a lighting device for _two lamps in which the 10 W and 6 W narrow tube fluorescent lamps La ₁ and La ₂ are combined. AC power supply across the fuse F, the rectifier DB is connected to a diode bridge via a surge absorbing element ZNR and filter circuit FL, capacitor C ₀ for smoothing between artery flow output ends of the rectifier DB is connected The AC voltage of the AC power supply AC is converted to a DC voltage. An inverter circuit 1 is connected between both ends of the capacitor C ₀ , and a 10 W narrow tube fluorescent lamp (hereinafter simply referred to as “fluorescent lamp”) La ₁ is loaded between the output terminals of the inverter circuit 1. 1 load circuit 2 ₁ ′ and 6
W tube diameter fluorescent lamp (hereinafter simply abbreviated as "fluorescent lamp") L
A _second load circuit 2 ₂ ′ having a load as a ₂ is connected in parallel.

The inverter circuit 1 includes a capacitor C₀Both
Choke coil L connected between the ends ₀And FET
Switching element Q and resistor R_TwoSeries circuit and switch
Element Q and resistor R_TwoConnected in parallel to the choke
Il L₀And a capacitor C forming a resonance circuit_TwoAnd the resistance
R₁Drive signal to the gate of the switching element Q through
Output control circuit (for example, AN6 manufactured by Matsushita Electronics Corporation)
766S). In addition, the first and
2 load circuit 2₁’, 2_Two’Is a fluorescent light L
a₁, La_TwoOne end of the filament is the inverter circuit 1
Choke coil L ₀Connected in parallel with each other at both ends
Fluorescent lamp La₁, La_TwoAnd each fluorescent lamp La₁, La_TwoNo
Capacitors connected between the other ends of the filaments
C₁’, C₁’And the choke coil L₀And switching
Connection point of element Q and each fluorescent lamp La₁, La_TwoFilament
Current limiting choke coil L inserted between one end of
₁’, L₁'And DC cut capacitors Cx, Cx
And a series circuit.

Further, a current limiting choke coil L₁’,
L₁'Each have a secondary winding n_Two’, N _Two’
These secondary windings n_Two’, N_TwoPp
Value detection circuit 3₁, 3_Two, And the above voltage pp
When the value exceeds a predetermined value (described later), the detection circuit 3₁,
3_TwoOutputs a detection signal to the control circuit IC.
ing.

Thus, switching is performed by the control circuit IC.
By turning the element Q on and off at high frequency,
Cucoil L₀And capacitor C_ThreeResonates and chokes
Le L ₀Resonance voltage is generated at both ends of the
The choke coil L₁’, L ₁’, Capacitor C₁’,
C₁'And the resonance system of the capacitors Cx and Cx
Each fluorescent lamp La₁, La_TwoHigh frequency power is supplied to the
Light La₁, La_TwoAre high frequency lighting
You.

[0009]

However, comparing the starting voltages of the 10 W fluorescent lamp La ₁ and the 6 W fluorescent lamp La ₂ , as shown in FIG. 3, the starting voltage of the 10 W fluorescent lamp La ₁ is 540 Vrms. , Whereas a 6W fluorescent lamp L
starting voltage of a ₂ there is only 400Vrms. That is, 10
If the circuit constants such as the choke coil L ₁ ′ and the capacitor C ₁ ′ are set in accordance with the W fluorescent lamp La ₁ , the 6 W fluorescent lamp La ₂ can be sufficiently started and lit. first load circuit 2 ₁ and the second load circuit 2 _second resonance conditions (choke coil L ₁ 'and capacitor C
Has ₁ 'circuit constants), such as the same, had it closely approximates the characteristics obtained characteristic during steady lighting to the rated lamp current and the rated lamp voltage of the fluorescent lamp La _1, La ₂ in doing so.

In the meantime, it is difficult for a general fluorescent lamp to emit light in a so-called half-wave (half-wave discharge) because the fluorescent lamp does not normally light up due to exhaustion or scattering of a filament emitter at the end of the life of the fluorescent lamp. It is well known as life characteristics. At the time of the above half-wave lighting, a rise in lamp impedance equivalent to a rise in lamp voltage of a fluorescent lamp causes
It is well known in operation of a resonance circuit that the resonance condition of the resonance circuit approaches the resonance condition at the time of starting.

On the other hand, in the above-mentioned conventional apparatus, a 10 W fluorescent lamp L is used.
The fluorescent lamp La ₂ of a ₁ and 6W from the fact that is started and turned at the same resonance condition, the fluorescent lamp higher stress than the fluorescent lamp La ₁ of 10W at end of life with respect to La ₂ of 6W, ie very A high lamp voltage is applied to the filament, and at the end of life, the filament is red-heated due to an increase in the cathode drop voltage of the filament whose emitter has decreased and the temperature of the tube wall (glass portion) near the filament increases. Had the disadvantage that

Here, the fluorescent lamps La ₁ and L having a small tube diameter are used.
a _2, which has the filaments at both ends of the glass tube has a structure disposed in the tube wall and the close position of the glass tube to narrow the pipe diameter. A synthetic resin base is provided so as to cover the filament, and a pair of terminal pins connected to the filament protrude from the base. The reason why the base is made of synthetic resin is to enhance the mass productivity of the structure for connecting the filament and the terminal pin of the glass tube having a small diameter of 8 mm. As described above, the fluorescent lamps La ₁ , L
In a _2, the temperature of the filament to a very short distance between the filament and the tube wall of the glass tube is easily transmitted to the pipe wall, there is a risk of deforming the base part made of a synthetic resin by the heat.

On the other hand, in the above-mentioned conventional apparatus, the voltages (the fluorescent lamps La ₁ , La ₁₎ detected by the detection circuits 3 ₁ , 3 _{2 are} detected.
₂ ), a detection signal is output when the voltage exceeds a threshold value lower than a level at which the temperature of the synthetic resin base portion is thermally deformed. The control circuit IC that has received the signal increases the oscillation frequency of the switching element Q and lowers the level of the high-frequency output of the inverter circuit 1. However, 10W
For the starting voltage of the fluorescent lamp La fluorescent lamp La ₂ of 6W compared to ₁ is low, be lowered to the output level that can not be fluorescent lamp La ₁ in sustaining the 10 W, at its output level 6
Since the W fluorescent lamp La ₂ can be maintained sufficiently lit,
W fluorescent lamp La ₂ there is a problem that continues the lighting of the. In this case, although the temperature rise of the glass tube wall is suppressed, there is a problem that the application of the stress to the filament is continued due to the continued lighting.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems, and it is possible to make different kinds of discharge lamps having a relatively small tube diameter and different rated outputs substantially light up at the rated time, and at the end of the life of the discharge lamp. An object of the present invention is to provide a discharge lamp lighting device capable of reducing stress for all discharge lamps.

[0015]

According to a first aspect of the present invention, a power supply unit for supplying a direct current and an inverter circuit for converting a direct current supplied from the power supply unit to a high-frequency alternating current are provided. A first load circuit having a first discharge lamp having a relatively small tube diameter, wherein the first discharge lamp is illuminated at a high frequency with high frequency power supplied from an inverter circuit; A second load circuit having a second discharge lamp having a different starting voltage and rated characteristics from the first discharge lamp, wherein the second discharge lamp is illuminated at a high frequency with high frequency power supplied from an inverter circuit, and a first discharge lamp And a second detection circuit for detecting a voltage corresponding to the lamp voltage of the first discharge lamp and detecting a voltage corresponding to the lamp voltage of the second discharge lamp to detect the occurrence of abnormality in the first discharge lamp. The second to determine the occurrence of abnormality in the discharge lamp
And the output frequency of the inverter circuit by controlling the operating frequency of the inverter circuit and the first and second detection circuits.
And a control circuit that controls the operating frequency so as to reduce the output of the inverter circuit when it is determined that an abnormality has occurred in at least one of the detection circuits. The circuit conditions of the first and second load circuits are individually set so as to be obtained at the same operating frequency, and the control circuit controls each of the discharge lamps when the first and second discharge lamps are on. Characterized in that the first and second discharge lamps of different diameters having relatively small tube diameters and different rated outputs are operated at approximately rated lighting by operating the inverter circuit within the optimum operating frequency range. At the same time, it is possible to reduce stress on all the discharge lamps at the end of the life of at least one of the first and second discharge lamps.

According to a second aspect of the present invention, the inverter circuit includes a series circuit of a choke coil and a switching element connected between the output terminals of the power supply unit, and a choke when the switching element is turned on and off at a high frequency. The first load circuit includes a coil and a capacitor that resonates, the first load circuit includes an inductance element and a capacitance element connected to a filament of the first discharge lamp to form a resonance circuit, and the second load circuit includes a second load circuit. And a capacitance element connected to the filament of the second discharge lamp to form a resonance circuit, wherein the first and second discharge lamps have the same starting voltage at the same operating frequency. Even when the constants of the inductance element and the capacitance element of the second load circuit are individually set, the tube diameter is not changed as in the case of the first aspect. The first and second discharge lamps, which are thin and different in rated output, can be operated substantially at rated light, and at the end of the life of at least one of the first and second discharge lamps, stress is reduced for all discharge lamps. Reduction can be achieved.

According to a third aspect of the present invention, the inverter circuit includes a series circuit of a pair of switching elements which are alternately turned on and off at a high frequency by a control circuit and are connected between output terminals of a power supply unit. The first and second load circuits may be connected in parallel to one of the pair of switching elements. Further, as in the invention of claim 4,
The first discharge lamp has a tube diameter of at least about 8 mm, a rated power of 10 W, and is made of a fluorescent lamp whose bases provided at both ends of the tube are made of synthetic resin. The second discharge lamp has a tube diameter of at least about 8 mm. In the case where the rated power is 6 W and the bases provided at both ends of the tube are made of a synthetic resin fluorescent lamp, different types of first and second discharge lamps having a relatively small tube diameter and different rated outputs are generally used. It is possible to perform rated lighting and to reduce stress on all discharge lamps at least at the end of the life of at least one of the first and second discharge lamps.

[0018]

(Embodiment 1) FIG. 1 is a circuit diagram showing Embodiment 1 of the present invention. However, since the circuit configuration of the present embodiment is almost the same as that of the conventional example, common portions are denoted by the same reference numerals, description thereof will be omitted, and only the features that are the features of the present embodiment will be described.

In the conventional example, the constant of the choke coil L ₁ ′ and the capacitor C ₁ ′ in the first load circuit 2 ₁ ′ including the fluorescent lamp La _{1 of} 10 W, and the second load including the fluorescent lamp La _{2 of} 6 W. The choke coil L ₁ ′ in the circuit 2 ₂ ′,
Although the constant of the capacitor C ₁ ′ has been made equal, in the present embodiment, the constant of the choke coil L _{1 of the first} load circuit 21 and the constant of the capacitor C ₁ are changed to the choke coil L _{2 of the second} load circuit 22. and are set to different constants and constants of the capacitor C _2, this embodiment is characterized in that point.

Here, the point for setting the above constant is:
Operating frequency (switching) of inverter circuit 1 at start
The on / off frequency of element Q) f₁And when
Working frequency f₁10W discharge lamp La₁Shown in FIG.
Starting voltage (= 540Vrms) is applied and 6W
Discharge lamp La_TwoThe starting voltage (= 400 Vrm) shown in FIG.
s) so that the choke coil L₁, L_TwoPassing
And capacitor C₁, C _TwoIs to set a constant.
Then, each of the fluorescent lamps L when the constants are set in this manner.
a₁, La_TwoFIG. 2 shows the resonance characteristics. What
The curve a in FIG. 2 is a 10 W fluorescent lamp La.₁Innocence of
The resonance characteristics at the time of loading (before starting) and the curve B are the fluorescent lamp La₁Point of
Resonance characteristics at the time of lighting, curve C is a 6W fluorescent lamp La_TwoNo load
The resonance characteristic at the time, the curve d is the fluorescent lamp La_TwoResonance characteristics when lighting
Expresses gender.

On the other hand, as shown in FIG.
a₁The optimal operating frequency when lighting _Three, 6W fluorescent lamp L
a_TwoThe optimal operating frequency when lighting_FourIf it is lit
Operating frequency f of the inverter circuit 1_TwoTo f_Three≤ f_Two≤ f
_FourAnd the control circuit IC sets the above operating frequency.
Wave number f_TwoDrives the switching element Q. Thus,
When the inverter circuit 1 is turned on, the frequency f_TwoWork with
For example, as is apparent from FIG. 2, a 10 W fluorescent lamp La₁When
6W fluorescent lamp La_TwoLights in a state close to the rated characteristics
be able to.

When the detection signals are output from the detection circuits 3 ₁ and 3 ₂ at the end of the life of the fluorescent lamps La ₁ and La ₂ ,
Conventional example of a high-frequency output of the inverter circuit 1 by changing a frequency higher than f ₄ similarly control circuit IC the operating frequency f of the inverter circuit 1 from f _2, different rated outputs two fluorescent lamps La _{Both 1} and La ₂ can be reduced to a level at which lighting cannot be maintained.
That is, in the present embodiment, by setting the above constants, 10
Since W and two fluorescent lamps La _1, the operating frequency f ₁ that optimum starting voltages of La ₂ is obtained of 6W is made to be the same, one of the at least one fluorescent lamp La _1, La
₂ reaches the end of life, both fluorescent lamps La ₁ , La
The output of ₂ can be reduced (or turned off).
For this reason, the fluorescent lamp La ₂ of 6 W having a lower starting voltage continues to be lit as a problem in the conventional example,
Although the temperature rise of the glass tube wall can be suppressed, it is possible to solve the problem that the application of the stress to the filament is continued by continuing the lighting.

(Embodiment 2) FIG. 4 shows Embodiment 2 of the present invention.
FIG. However, since the basic configuration of this embodiment is the same as that of the first embodiment, common portions are denoted by the same reference numerals and description thereof is omitted. This embodiment differs from the first embodiment in the configuration of the inverter circuit 1. In other words, the inverter circuit 1 of the present embodiment connects a series circuit of a pair of switching elements Q ₁ and Q ₂ composed of FETs between both ends of a smoothing capacitor C ₀ , and connects both ends of a high-potential side switching element Q ₁ . The first and second load circuits 2 ₁ and 2 ₂ are connected in parallel, and a pair of switching elements Q ₁ and Q ₂ are alternately turned on and off at a high frequency by a control circuit IC. Since the inverter circuit 1 having such a circuit configuration is conventionally well-known, a detailed description of its operation will be omitted.

Thus, the configuration of the inverter circuit 1 is different.
However, this embodiment is the same as in the first embodiment.
10W and 6W fluorescent lamps La at operating frequencies₁, La_Twoof
Choke coil L to ensure the optimal starting voltage₁,
L_TwoAnd capacitor C₁, C_TwoSet constant and light
Sometimes two types of fluorescent lamp La₁, La_TwoThe point in the best condition
Operate within the operating frequency range that can be lit,
Both fluorescent lamps La₁, La _TwoAbout appropriate near the rated characteristics
Lighting characteristics can be obtained. Also, the same as in the first embodiment
At least one of the fluorescent lamps La₁, La_TwoIs longevity
In the case of the end of life, the fluorescent lamp La of 6 W with the lower starting voltage
_TwoCan prevent excessive stress from being applied to the
Wear.

[0025]

According to the first aspect of the present invention, there is provided a power supply unit for supplying a direct current, an inverter circuit for converting the direct current supplied from the power supply unit to a high-frequency alternating current, and a first discharge lamp having a relatively small tube diameter. With the high frequency power supplied from the inverter circuit.
And a second discharge lamp having a relatively small tube diameter and a starting voltage and a rated characteristic different from those of the first discharge lamp and supplied from an inverter circuit. A second load circuit for illuminating the second discharge lamp at high frequency with high frequency power, and a second load circuit for detecting presence / absence of abnormality of the first discharge lamp by detecting a voltage corresponding to a lamp voltage of the first discharge lamp. A first detection circuit, a second detection circuit that detects a voltage corresponding to a lamp voltage of the second discharge lamp to determine whether an abnormality has occurred in the second discharge lamp, and an operating frequency of the inverter circuit. And a control circuit for controlling the operating frequency so as to reduce the output of the inverter circuit when at least one of the first and second detection circuits determines that an abnormality has occurred. , First
And the circuit conditions of the first and second load circuits are individually set so that the starting voltages of the first and second discharge lamps are obtained at the same operating frequency, and the control circuit controls the first and second discharge circuits. Since the inverter circuit is operated within the range of the optimum operating frequency of each discharge lamp when the electric lamp is lit, the first and second discharge lamps having different tube diameters and different rated outputs are used. The lamps can be turned on at approximately rated power, and at the end of the life of at least one of the first and second discharge lamps, it is possible to reduce stress on all the discharge lamps.

[Brief description of the drawings]

FIG. 1 is a schematic circuit diagram showing a first embodiment.

FIG. 2 is a diagram showing resonance characteristics of first and second load circuits in the first embodiment.

FIG. 3 is a diagram showing characteristics of two types of fluorescent lamps in the above.

FIG. 4 is a schematic circuit diagram showing a second embodiment.

FIG. 5 is a schematic circuit diagram showing a conventional example.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 inverter circuit 2 ₁ first load circuit 2 ₂ second load circuit 3 ₁ , 3 ₂ detection circuit Q switching element La ₁ 10 W fluorescent lamp La ₂ 6 W fluorescent lamp L ₁ , L ₂ choke coil C ₁ , C _2- capacitor IC control circuit

Claims (4)

[Claims] 1. A power supply unit for supplying a direct current, an inverter circuit for converting a direct current supplied from the power supply unit to a high-frequency alternating current, and a first discharge lamp having a relatively small diameter. A first load circuit in which the first discharge lamp is turned on at a high frequency with high frequency power, and a second discharge lamp having a relatively small tube diameter and a starting voltage and a rated characteristic different from those of the first discharge lamp. A second load circuit in which the second discharge lamp is turned on at a high frequency with the high-frequency power supplied from the inverter circuit;
A first detection circuit that detects a voltage corresponding to a lamp voltage of the first discharge lamp to determine whether an abnormality has occurred in the first discharge lamp; and detects a voltage corresponding to a lamp voltage of the second discharge lamp. A second detection circuit for determining whether or not an abnormality has occurred in the second discharge lamp; and controlling the operating frequency of the inverter circuit to vary the output of the inverter circuit and at least one of the first and second detection circuits. On the other hand, a control circuit that controls the operating frequency so as to reduce the output of the inverter circuit when it is determined that an abnormality has occurred, wherein the starting voltages of the first and second discharge lamps are at the same operating frequency. The circuit conditions of the first and second load circuits are individually set so as to be obtained, and the control circuit determines the optimum operating frequency of each discharge lamp when the first and second discharge lamps are lit. Operate the inverter circuit within the range The discharge lamp lighting device according to claim and. 2. An inverter circuit comprising: a series circuit of a choke coil and a switching element connected between output terminals of a power supply unit; and a capacitor that resonates with the choke coil when the switching element is turned on and off at a high frequency. , The first load circuit includes an inductance element and a capacitance element connected to the filament of the first discharge lamp to form a resonance circuit, and the second load circuit is connected to the filament of the second discharge lamp. And an inductance element and a capacitance element forming a resonance circuit.
It is characterized in that constants of inductance elements and capacitance elements of the first and second load circuits are individually set so that starting voltages of the first and second discharge lamps can be obtained at the same operating frequency. The discharge lamp lighting device according to claim 1, wherein 3. The inverter circuit includes a series circuit of a pair of switching elements that are alternately turned on and off at a high frequency by a control circuit and that is connected between output terminals of a power supply unit. And a first load circuit and a second load circuit connected in parallel.
The discharge lamp lighting device as described in the above. 4. The first discharge lamp has a tube diameter of at least about 8
mm, a rated power of 10 W, and a base provided at both ends of the tube is made of a fluorescent lamp made of synthetic resin. The second discharge lamp has a tube diameter of at least about 8 mm, a rated power of 6 W, and a base provided at both ends of the tube. 4. The discharge lamp lighting device according to claim 1, wherein the portion is made of a fluorescent lamp made of synthetic resin.