JP4283348B2 - Discharge lamp lighting device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a discharge lamp lighting device for starting and lighting a plurality of types of discharge lamps (particularly fluorescent lamps) having different rated outputs using an inverter circuit.
[0002]
[Prior art]
Conventionally, as a lighting device for starting and lighting a discharge lamp such as a fluorescent lamp, a DC power source obtained by rectifying and smoothing an AC power source is converted into high frequency power of about 50 kHz by an inverter circuit and supplied to the discharge lamp. A discharge lamp lighting device for lighting a discharge lamp at a high frequency of about 50 kHz is well known.
[0003]
In addition, it is well known that there are types of fluorescent lamps such as a straight tube fluorescent lamp and a ring fluorescent lamp. However, in recent years, a fluorescent lamp with a thin tube diameter (hereinafter referred to as “ The demand for “thin tube fluorescent lamps” is increasing. Furthermore, high-efficiency thin tube fluorescent lamps are turned on at a high frequency, thereby increasing the amount of light output per supplied power and attracting attention as environmentally friendly lighting.
[0004]
However, in general, a fluorescent lamp has a high lamp voltage when the tube diameter is reduced, and particularly a very high starting voltage (for example, 500 V or more) is required at the time of starting. The point which requires a high starting voltage is a big subject. In addition, it is already known that there are tubes having a tube diameter of 8 [mm] and rated outputs of 10 W and 6 W as the above-mentioned thin tube diameter fluorescent lamps. The discharge lamp lighting device to be used has already been commercialized.
[0005]
FIG. 5 is a circuit diagram showing an example of a two-lamp lighting device in which the 10 W and 6 W thin tube fluorescent lamps La ₁ and La ₂ are combined. A rectifier DB comprising a diode bridge is connected to both ends of the AC power supply AC via a fuse F, a surge absorbing element ZNR and a filter circuit FL, and a smoothing capacitor C ₀ is connected between the pulsating output terminals of the rectifier DB. The AC voltage of the AC power source AC is converted into a DC voltage. An inverter circuit 1 is connected between both ends of the capacitor C ₀ , and a 10 W thin tube fluorescent lamp (hereinafter simply referred to as “fluorescent lamp”) La ₁ is loaded between the output terminals of the inverter circuit 1. 1 of the load circuit _{2. 1} 'and capillary径蛍light lamp 6W (hereinafter, simply referred to as "fluorescent light".) the second load circuit to La ₂ load 2 _2' are connected in parallel .
[0006]
The inverter circuit 1 includes a series circuit of the switching element Q and a resistor R ₂ consisting of the choke coil L ₀ and FET connected across the capacitor C _0, the choke coil L is connected in parallel to the switching element Q and the resistor R _{2 0} and a capacitor C ₂ that forms a resonance circuit, and a control circuit (for example, AN6766S manufactured by Matsushita Electronics Co., Ltd.) IC that outputs a drive signal to the gate of the switching element Q via a resistor R ₁ . Further, the first and second load circuits 2 ₁ ′ and 2 ₂ ′ are fluorescent lights in which one ends of filaments of the fluorescent lamps La ₁ and La ₂ are connected in parallel to both ends of the choke coil L ₀ of the inverter circuit 1, respectively. Lamps La ₁ , La ₂ , capacitors C ₁ ′, C ₁ ′ connected between the other ends of the filaments of the fluorescent lamps La ₁ , La ₂ , connection points of the choke coil L ₀ and the switching element Q, and Current limiting choke coils L ₁ ′ and L ₁ ′ inserted between one end of the filaments of the fluorescent lamps La ₁ and La ₂ and a series circuit of DC cutting capacitors Cx and Cx are provided.
[0007]
Furthermore, the choke coil L ₁ of the current limiting ', L _1' each secondary winding n ₂ is the ', n _2' is provided with a, a voltage generated in these secondary winding n ₂ ', n _2' The detection circuit 3 ₁ , 3 ₂ detects the pp value, and when the pp value of the voltage exceeds a predetermined value (described later), a detection signal is sent from the detection circuit 3 ₁ , 3 ₂ to the control circuit IC. Is output.
[0008]
Thus, when the switching element Q is turned on / off at a high frequency by the control circuit IC, the choke coil L ₀ and the capacitor C ₃ resonate to generate a resonance voltage at both ends of the choke coil L _0. choke coil L ₁ a ', L _1', a capacitor C ₁ ', C _1' and the capacitor Cx, the high frequency power is supplied to resonate in each fluorescent lamp La _1, La ₂ in the resonance system of Cx, the fluorescent lamp La ₁ , La ₂ are each lit at high frequency.
[0009]
[Problems to be solved by the invention]
However, when the starting voltages of the 10 W fluorescent lamp La ₁ and the 6 W fluorescent lamp La ₂ are compared, the starting voltage of the 10 W fluorescent lamp La ₁ is 540 Vrms as shown in FIG. The starting voltage of the lamp La ₂ is only 400 Vrms. That is, if circuit constants such as the choke coil L ₁ ′ and the capacitor C ₁ ′ are set in accordance with the 10 W fluorescent lamp La ₁ , the 6 W fluorescent lamp La ₂ can be sufficiently started and lit. Conventionally, the resonance conditions (circuit constants such as choke coil L ₁ ′ and capacitor C ₁ ′) of the first load circuit 2 ₁ and the second load circuit 2 ₂ are made the same, so that at the time of steady lighting As for the characteristics, the characteristics approximately similar to the rated lamp current and the rated lamp voltage of the fluorescent lamps La ₁ and La ₂ were obtained.
[0010]
By the way, at the end of the life of a fluorescent lamp, the fluorescent lamp gradually stops normal lighting due to exhaustion or scattering of the filament emitter, and so-called half-wave lighting (half-wave discharge) is a typical life characteristic of a fluorescent lamp. Well known. It is well known in the operation of the resonance circuit that the resonance condition of the resonance circuit becomes close to the resonance condition at the start-up due to the increase in lamp impedance equivalent to the increase in the lamp voltage of the fluorescent lamp during the half-wave lighting. Yes.
[0011]
On the other hand, in the above-mentioned conventional apparatus, the 10 W fluorescent lamp La ₁ and the 6 W fluorescent lamp La ₂ are started and lit under the same resonance conditions, so that the 6 W fluorescent lamp La ₂ has a 10 W fluorescent light at the end of its life. A higher stress than the lamp La ₁ , that is, a very high lamp voltage, is applied, and the filament becomes red hot due to an increase in the cathode fall voltage of the filament whose emitter at the end of life has decreased, and the tube wall ( The temperature of the glass part) was increased.
[0012]
Here, the fluorescent lamps La ₁ and La ₂ having a thin tube diameter have filaments at both ends of the glass tube, but are arranged close to the tube wall of the glass tube because the tube diameter is thin. ing. A base portion made of synthetic resin is provided so as to cover the filament, and a pair of terminal pins connected to the filament are projected from the base portion. The reason why the cap portion is made of a synthetic resin is to increase the mass productivity of the structure in which the filament and the terminal pin of the glass tube having a thin tube diameter of 8 mm are connected. Thus, in the fluorescent lamps La ₁ and La _{2 having} a small tube diameter, since the distance between the filament and the tube wall of the glass tube is very close, the temperature of the filament is easily transmitted to the tube wall. There is a possibility that the base part may be deformed.
[0013]
On the other hand, in the above-described conventional apparatus, the voltage detected by the detection circuits 3 ₁ and 3 ₂ (voltage corresponding to the lamp voltage of the fluorescent lamps La ₁ and La ₂ ) is the temperature at which the base portion made of synthetic resin is thermally deformed. A detection signal is output when a threshold value set lower than a level such that the control circuit IC is received, and the control circuit IC receiving this detection signal raises the oscillation frequency of the switching element Q to increase the high frequency of the inverter circuit 1. The output level was lowered. However, since 10W starting voltage of the fluorescent lamp La fluorescent lamp La ₂ of 6W compared to ₁ is low, it is lowered to the output level that can not be fluorescent lamp La ₁ in sustaining the 10W, fluorescent lamp 6W at its output level There is a problem that the 6 W fluorescent lamp La ₂ continues to be lit because La ₂ can be sufficiently lit. In this case, although the temperature rise of the glass tube wall can be suppressed, there is a problem that the application of stress to the filament is continued by continuing lighting.
[0014]
The present invention aims to solve the above-mentioned problems, and can discharge different types of discharge lamps having relatively small tube diameters and different rated outputs, and can discharge all lamps 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 the stress of an electric lamp.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, a first aspect of the present invention provides a power supply section that supplies direct current, an inverter circuit that converts direct current supplied from the power supply section into high-frequency alternating current, and a first that has a relatively small tube diameter. A first load circuit that has a discharge lamp and is driven at high frequency by high-frequency power supplied from an inverter circuit, a relatively narrow tube diameter, and the first discharge lamp, starting voltage, and rated characteristics A second load circuit having a second discharge lamp having a different frequency and a high frequency power supplied from an inverter circuit to turn on the second discharge lamp at a high frequency, and detecting a voltage corresponding to the lamp voltage of the first discharge lamp The first detection circuit for determining whether or not the first discharge lamp is abnormal and the voltage corresponding to the lamp voltage of the second discharge lamp are detected to determine whether or not the second discharge lamp is abnormal The second detection circuit that controls the operating frequency of the inverter circuit A control circuit that varies the output of the inverter circuit and 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 first and second detection circuits. Each of the circuit conditions of the first and second load circuits is individually set so that the starting voltages of the first and second discharge lamps can be obtained at the same operating frequency. The inverter circuit is operated within the range of the optimum operating frequency of each discharge lamp when the second discharge lamp is lit, and it is characterized by having a relatively thin tube diameter and different rated output. The first and second discharge lamps can be lighted at a substantially rated level, and stress can be reduced for all the discharge lamps at the end of the lifetime of either the first or second discharge lamp.
[0016]
Further, as in the invention of claim 2, the inverter circuit has a series circuit of a choke coil and a switching element connected between the output terminals of the power supply unit, and resonates with the choke coil when the switching element is turned on / 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 includes a second discharge circuit. An inductance element and a capacitance element connected to the filament of the lamp to form a resonant circuit, and the first and second discharge voltages are obtained at the same operating frequency so that the starting voltages of the first and second discharge lamps are obtained at the same operating frequency; Even if the constants of the inductance elements and the capacitance elements of the load circuit are individually set, the tube diameter is relatively small as in the first aspect of the invention. Different types of first and second discharge lamps having different rated outputs can be lit approximately at rated power, and at least at the end of the lifetime of either the first or second discharge lamp, stress can be reduced for all the discharge lamps. Is possible.
[0017]
As in the third aspect of the invention, 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 the control circuit and connected between the output terminals of the power supply unit. The first and second load circuits may be connected in parallel to any one of the switching elements.
Further, as in the invention of claim 4, the first discharge lamp comprises a fluorescent lamp having a tube diameter of at least about 8 mm, a rated power of 10 W, and a cap portion provided at both ends of the tube made of a synthetic resin. The discharge lamp of this type has a tube diameter that is at least about 8 mm, a rated power of 6 W, and a fluorescent lamp that has a base made of synthetic resin at both ends of the tube. The first and second discharge lamps can be substantially lit at the same time, and stress can be reduced for all the discharge lamps at the end of the lifetime of either the first or second discharge lamp.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
(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 is omitted, and only portions that are characteristic of the present embodiment will be described.
[0019]
In the conventional example, the constants of the choke coil L ₁ ′ and the capacitor C ₁ ′ in the first load circuit 2 ₁ ′ including the 10 W fluorescent lamp La ₁ and the second load circuit 2 ₂ including the 6 W fluorescent lamp La ₂ are used. 'choke coil L ₁ in', had been equal to the constant of the capacitor C ₁ ', in this embodiment, the first choke constant of the coil L ₁ and the capacitor C ₁ of the load circuit 2 ₁ second load are set to different and circuit 2 ₂ of the choke constant of the coil L ₂ and capacitor C ₂ constant, this embodiment is characterized in that point.
[0020]
Here, the point of setting the constants, the operating frequency (on-off frequency of the switching element Q) of the inverter circuit 1 at the time of starting the f is taken as f _1, at the operating frequency f ₁ 10 W of the discharge lamp La _The choke coils L ₁ and L ₂ are applied so that the starting voltage (= 540 Vrms) shown in FIG. 3 is applied to ₁ and the starting voltage (= 400 Vrms) shown in FIG. 3 is applied to the 6 W discharge lamp La ₂ . And the constants of the capacitors C ₁ and C ₂ are set. FIG. 2 shows the resonance characteristics of the fluorescent lamps La ₁ and La ₂ when the constants are set in this way. 2 is a resonance characteristic when the 10 W fluorescent lamp La ₁ is not loaded (before starting), curve B is a resonance characteristic when the fluorescent lamp La ₁ is turned on, and curve C is a 6 W fluorescent lamp La ₂ . Resonance characteristics when there is no load, and curve D represent the resonance characteristics when the fluorescent lamp La ₂ is lit.
[0021]
On the other hand, as shown in FIG. 2, if the optimum operating frequency when the 10 W fluorescent lamp La ₁ is lit is f ₃ and the optimum operating frequency when the 6 W fluorescent lamp La ₂ is lit is f ₄ , the inverter circuit is turned on. 1 of the operating frequency f ₂ is set to a frequency to be _{f 3 ≦ f 2 ≦ f 4} , to drive the switching element Q at the operating frequency f ₂ by the control circuit IC. Thus, when the inverter circuit 1 is operated at the frequency f ₂ during lighting, the 10 W fluorescent lamp La ₁ and the 6 W fluorescent lamp La ₂ are lit in a state close to the rated characteristics, as is apparent from FIG. Can do.
[0022]
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 , the control circuit IC changes the operating frequency f of the inverter circuit 1 from f ₂ to f as in the conventional example. _By changing the frequency to a frequency higher than _4, the high-frequency output of the inverter circuit 1 can be lowered to a level at which both of the two types of fluorescent lamps La ₁ and La ₂ having different rated outputs cannot be lit. That is, in the present embodiment, by setting the above constants, the operating frequencies f _{1 at} which the optimum starting voltages of the two types of fluorescent lamps La ₁ and La ₂ of 10 W and 6 W can be obtained are the same. When one of the fluorescent lamps La ₁ and La ₂ reaches the end of its life, the output of both fluorescent lamps La ₁ and La ₂ can be reduced (or turned off). For this reason, the fluorescent lamp La ₂ having a lower starting voltage continues to be lit as had been a problem in the conventional example, and although the temperature rise of the glass tube wall can be suppressed, the lighting continues to the filament. The problem that the application of the stress continues can be solved.
[0023]
(Embodiment 2)
FIG. 4 is a circuit diagram showing Embodiment 2 of the present invention. However, since the basic configuration of the present embodiment is common to that of the first embodiment, common portions are denoted by the same reference numerals and description thereof is omitted.
This embodiment is different from the first embodiment in the configuration of the inverter circuit 1. That is, the inverter circuit 1 in this embodiment is connected a series circuit of a pair of switching elements Q _1, Q ₂ consisting FET across capacitor C ₀ for smoothing, the high potential side ends of the switching element Q ₁ The first and second load circuits 2 ₁ and 2 ₂ are connected in parallel, and the pair of switching elements Q ₁ and Q ₂ are alternately turned on and off at a high frequency by the control circuit IC. Since the inverter circuit 1 having such a circuit configuration is well known in the art, a detailed description of its operation is omitted.
[0024]
Thus, although the configuration of the inverter circuit 1 is different, in this embodiment as well as in the first embodiment, the choke is ensured so that the optimum starting voltage of the 10 W and 6 W fluorescent lamps La ₁ and La ₂ can be secured at the same operating frequency. The constants of the coils L ₁ and L _{2 and the} capacitors C ₁ and C ₂ are set so that the two fluorescent lamps La ₁ and La ₂ can be operated within an operating frequency range in which they can be lit in an optimum state at the time of lighting. Thus, it is possible to obtain substantially appropriate lighting characteristics close to the rated characteristics for both fluorescent lamps La ₁ and La ₂ . Similarly to the first embodiment, when at least one of the fluorescent lamps La ₁ and La ₂ is at the end of its life, it is possible to prevent an excessive stress from being applied to the 6 W fluorescent lamp La ₂ having a lower starting voltage. can do.
[0025]
【The invention's effect】
The invention of claim 1 includes a power supply unit that supplies direct current, an inverter circuit that converts direct current supplied from the power supply unit to high-frequency alternating current, and a first discharge lamp having a relatively small tube diameter. A first load circuit in which the first discharge lamp is operated at a high frequency with the supplied high-frequency power, and a second discharge lamp having a relatively small tube diameter and a different starting voltage and rated characteristics from the first discharge lamp. A second load circuit in which the second discharge lamp is lit at a high frequency with the high-frequency power supplied from the inverter circuit, and a voltage corresponding to the lamp voltage of the first discharge lamp is detected to detect the first discharge lamp A first detection circuit for determining whether or not an abnormality has occurred; a second detection circuit for detecting whether or not an abnormality has occurred in the second discharge lamp by detecting a voltage corresponding to the lamp voltage of the second discharge lamp; Inverter circuit output by controlling the inverter circuit operating frequency And a control circuit that controls the operating frequency so as to lower the output of the inverter circuit when it is determined that an abnormality has occurred in at least one of the first and second detection circuits. The circuit conditions of the first and second load circuits are individually set so that the starting voltages of the discharge lamps can be obtained at the same operating frequency. The control circuit turns on the first and second discharge lamps. Since the inverter circuit is operated within the range of the optimum operating frequency of each discharge lamp, the different first and second discharge lamps having relatively small tube diameters and different rated outputs are omitted. The rated lighting can be performed, and at the end of the life of at least one of the first and second discharge lamps, it is possible to reduce the stress for 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 same as above.
FIG. 3 is a diagram showing the characteristics of two types of fluorescent lamps.
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]
DESCRIPTION OF SYMBOLS 1 Inverter circuit 2 ₁ 1st load circuit 2 ₂ 2nd load circuit 3 ₁ , 3 ₂ detection circuit Q Switching element La ₁ 10W fluorescent lamp La ₂ 6W fluorescent lamp L ₁ , L ₂ choke coils C ₁ , C _2- capacitor IC control circuit

Claims (4)

A power supply unit that supplies direct current, an inverter circuit that converts direct current supplied from the power supply unit into high-frequency alternating current, and a first discharge lamp that has a relatively small tube diameter, and the first high-frequency power that is supplied from the inverter circuit. A first load circuit in which one discharge lamp is lit at a high frequency, and a second discharge lamp having a relatively small tube diameter and a different starting voltage and rated characteristics from the first discharge lamp and supplied from an inverter circuit. And detecting a voltage corresponding to the lamp voltage of the first discharge lamp to detect whether or not an abnormality has occurred in the first discharge lamp. Controls the operating frequency of the first detection circuit, the second detection circuit that detects a voltage corresponding to the lamp voltage of the second discharge lamp and determines whether or not an abnormality has occurred in the second discharge lamp, and the inverter circuit And changing the output of the inverter circuit 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 first and second detection circuits, and the first and second discharge lamps Each circuit condition of the first and second load circuits is individually set so that each starting voltage can be obtained at the same operating frequency, and the control circuit is when the first and second discharge lamps are lit. A discharge lamp lighting device comprising: operating an inverter circuit within an optimum operating frequency range of each discharge lamp. The inverter circuit includes a series circuit of a choke coil and a switching element connected between output terminals of the power supply unit, and a capacitor that resonates with the choke coil when the switching element is turned on / off at a high frequency. The circuit includes an inductance element and a capacitance element that are connected to the filament of the first discharge lamp to form a resonant circuit, and the second load circuit is connected to the filament of the second discharge lamp to form a resonant circuit Constants of the inductance elements and capacitance elements of the first and second load circuits so that the 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 the lamps are individually set. 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 the control circuit and connected between the output terminals of the power supply unit, and the first and second switching elements are connected to one of the pair of switching elements. The discharge lamp lighting device according to claim 1, wherein two load circuits are connected in parallel. The first discharge lamp is composed of a fluorescent lamp having at least a tube diameter of about 8 mm, a rated power of 10 W, and a base portion provided at both ends of the tube made of a synthetic resin. The second discharge lamp has at least a tube diameter of about 8 mm. 4. The discharge lamp lighting device according to claim 1, wherein the rated power is 6 W, and the cap portions provided at both ends of the tube are made of a fluorescent lamp made of synthetic resin.

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