JPH0574579A - Incandescent lamp lighting device - Google Patents

Abstract

PURPOSE:To stabilize the output voltage irrespective of the voltage variation of a power source. CONSTITUTION:An unstable oscillation circuit 5 to output the ON and OFF signal of a switching element SW, a Zener diode ZD1 to detect the oscillation voltage time applied to both ends of the switching element SW, and the like are provided. The oscillation voltage is applied to both ends of the switching element SW, the applied voltage is detected by the Zener doide ZD1, and a transistor Q is turned on by the signal phase at the part where the voltage is made at the Zener voltage or higher. As a result, even though there is an H level of output signal of the unstable oscillation circuit 5, the switching element SW is turned off by the turning ON of the transistor Q. Consequently, the signal width of the on duty signal of the switching element SW is made shorter when the input power source voltage is large, and made longer when the input power source voltage is small, contrarily, so as to control the output voltage constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an incandescent lamp lighting device for lighting an incandescent lamp including a mini halogen bulb through a lighting device that performs voltage conversion (step-down, frequency, etc.) or on / off control from a commercial power source. It is about.

[0002]

2. Description of the Related Art A lighting device having an inverter circuit for lighting a mini halogen bulb is disclosed in Japanese Patent Application No. 2-6.
There is a publication of 6888. This is because in order to stabilize the output against fluctuations in the power supply voltage, the output voltage and the input voltage are detected and fed back, and the high frequency in each phase of the output power supply of the rectification means of the inverter circuit is high. The method of controlling by changing the generation phase of the power supply is used.

As a second conventional example, there is a circuit as shown in FIG. In this conventional example, the commercial power source E is connected to the rectifier circuit DB.
After being rectified by, the input voltage is input to the inverter circuit 1 via the thyristor Q ₁ , the input voltage detection circuit 2 is connected to the output terminal of the rectification circuit DB, and the output signal is the phase control circuit 3 To control the thyristor Q ₁ .

In this circuit, a series circuit of a primary winding t ₁ of a transformer T and a switching element SW composed of an FET is connected to both ends of an output side (or a DC power source) of a thyristor Q _1. A capacitor C is connected to both ends of the primary winding t ₁ of the transformer T, and a lamp L (low-voltage mini halogen bulb) is connected to both ends of the secondary winding t ₂ via a diode D.

With such a circuit configuration, as shown in FIG. 6, the conduction phase of the thyristor Q ₁ is controlled (B in FIG. 6) according to the magnitude of the input voltage (B in FIG. 6) to output the output voltage. The effective value can be kept constant (C in FIG. 6). Here, the operation of the inverter circuit 1 will be described with reference to FIG. B is an output signal from the drive circuit 4, and its oscillation frequency and on-duty can be arbitrarily changed. The capacitor C may be connected in parallel with the switching element SW.

First, when the output signal a is turned on,
As shown in D, an oscillating current flows through the capacitor C from the inductance of the wiring or the like and is attenuated. Then, + charges are accumulated on the + side of the DC power source E of the capacitor C. After that, when the output signal a is turned off, the electric charge stored in the capacitor C is discharged through the primary winding t ₁ of the transformer T, but in this direction, the diode connected to the secondary winding t ₂ is discharged. The direction in which the current flows in the forward direction of D is 1
The inductance of the next winding t ₁ is very small, and a steep current flows in a moment to charge the capacitor C in the opposite manner to when it is turned on.

When the current flows in the opposite direction, the capacitor C is discharged in the same direction as when it was turned on.
Since the current flows in the opposite direction of the diode D connected to the secondary winding t ₂ and no current flows in the secondary winding t ₂ , the inductance of the primary winding t ₁ is Line t ₂
The output end of becomes the same condition as open and becomes larger. Therefore, the discharge current is small and the time constant is long. When off, the above damping vibration is performed, and finally the capacitor C
Current is zero. As a result, the switching element SW
An oscillating voltage as shown in C is applied to both ends of the. Further, since the current shown by E flows in the primary winding t ₁ of the transformer T, the current obtained by combining D and E flows in the switching element SW as shown in B.

[0008]

In the conventional device as described above, in which the high frequency oscillation start phase of the inverter circuit is controlled by feedback control with respect to power supply voltage fluctuation, the input current waveform is distorted and The wave current will increase and adversely affect the power factor improving capacitors at power plants.

Further, as in the second conventional example, the current and voltage rise suddenly, so that the noise becomes high,
There is a problem that the radio circuit becomes difficult to hear, and as a countermeasure, the filter circuit becomes large and the circuit cannot be made compact. It is an object of the present invention to provide an incandescent lamp lighting device capable of stabilizing an output voltage against fluctuations in power supply voltage with an extremely simple circuit configuration.

[0010]

According to the present invention, a DC power source is connected to one end of a primary winding of a transformer, a switching element is connected to the other end of the primary winding of the transformer, and A capacitor is connected in parallel with the next winding or in parallel with the switching element, and a diode is connected to the secondary winding of the transformer in a direction in which a current flows when the switching element is turned on to light the incandescent lamp. The incandescent lamp lighting device is provided with an oscillating voltage time detection circuit that detects the time of the oscillating voltage applied to both ends of the switching element and is proportional to the magnitude of the DC power supply, and according to the magnitude of the output of the oscillating voltage time detecting circuit. A drive circuit for making the output voltage of the switching element substantially constant is provided.

[0011]

Thus, the time of the oscillating voltage applied to both ends of the switching element and proportional to the magnitude of the DC power supply is detected, and the output voltage of the switching element is substantially constant according to the magnitude of the output of the oscillating voltage time detection circuit. The lamp voltage fluctuation caused by the fluctuation of the input power supply voltage is controlled, and the lamp voltage is controlled to be constant at all times to provide a high-quality luminaire with no flicker. The rated light output is obtained at voltage, and the lamp life is not impaired even when the input voltage is at the upper limit.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. The present invention suppresses the fluctuation of the lamp voltage that is the output even if the input power supply voltage fluctuates, and brings the lamp voltage at the rated time close to 12 V, for example, to increase the light output at the rated input voltage, and The lamp life is satisfied by making the lamp voltage not exceed 12 V even when the input power source voltage is high, while making the rated light output near the rated light output. still,
A low voltage mini halogen bulb is used as the lamp.

(Embodiment 1) The basic circuit configuration is shown in FIG.
This is the same as the conventional example of No. 2. Figure 1 shows the switching element SW
Showing the configuration of the drive circuit 4 for controlling the switching element
Resistor R on both ends of SW₁And R₂Connect the series circuit in parallel
And a Zener diode ZD at its connection point.₁Mosquito
Connect the sword and connect the Zener diode ZD₁Anno
Resistance R ₃Connected to the base of transistor Q via
ing.

A resistor R ₄ is connected between the base and emitter of the transistor Q, and the collector of the transistor Q is connected to the output terminal of the unstable oscillation circuit 5. This astable oscillator circuit 5 is a general-purpose one using a timer IC 6. Next, the circuit operation will be described with reference to FIG. By the OFF signal of the output signal B of the astable oscillation circuit 5,
An oscillating voltage is applied to both ends of the switching element SW, and a voltage b obtained by dividing the oscillating voltage is applied to both ends of the resistor R ₂ . The applied voltage B is detected by the Zener diode ZD ₁ ,
The signal phase at the portion where the Zener voltage V _ZD1 or higher becomes a waveform C, is input to the base of the transistor Q, and the transistor Q is turned on.

As a result, in the H level part of the waveform C,
Even if the H level of the output signal a of the astable oscillation circuit 5 exists, the gate of the switching element SW is short-circuited because the transistor Q is on, and the waveform c is at L level while it remains off. Then, the transistor Q is turned off, and the H level of the output signal a is applied to the gate of the switching element SW for the first time to turn on, and the ON period of the switching element SW at the rated time as shown by the waveform D is given. ..

In such a circuit configuration, when the input power supply voltage V _E changes, the resonance voltage waveform also changes, so the voltage waveform across the resistor R ₂ also changes as shown by the broken line in waveform B, and the input When the power supply voltage V _E becomes large,
When the phase extends (e in Fig. 2) and decreases, on the contrary,
The phase becomes shorter (Fig. 2, F). As a result, since the oscillation frequency is made constant by the astable oscillation circuit 5, the signal width of the on-duty signal of the switching element SW is
When the input power supply voltage V _E is high, the output voltage is shortened. Conversely, when the input power supply voltage V _E is low, the output power voltage V _E is increased, and the output voltage is controlled to be constant. Therefore, a constant light output can be obtained and high quality lighting can be provided.

Further, when the input power supply voltage V _E is at the upper limit, the voltage is set to 12 V in order to guarantee the lamp life, so that the rated voltage of the lamp is not given and the rated light output cannot be obtained at the rated power supply voltage. Such problems can be avoided. still,
An oscillating voltage time detection circuit is composed of the resistors R ₁ and R ₂ , the Zener diode ZD _{1 and the} like.

(Embodiment 2) The basic circuit of this embodiment is also the same as the second conventional example, and an embodiment of the drive circuit 4 is shown in FIG. As shown in FIG. 3, a series circuit of resistors R ₁ and R ₂ is connected to both ends of the switching element SW, and a zener diode ZD ₁ , a capacitor C ₁ and a resistor R ₃ are connected in series to both ends of the resistor R _2. The circuit is connected, and the anode of the Zener diode ZD ₁ is connected to one end of the input terminal of the AND gate G ₃ via the inverter gate G ₁ .

The capacitor C₁And resistance R₃Connection point
Is input to the trigger terminal of the first monostable oscillator circuit 6.
There is. The output terminal of the monostable oscillator circuit 6 is an inverter gate.
To G ₂, Capacitor C₂, Resistance R_FourA series circuit consisting of
Connected to the source of the switching element SW via
It Capacitor C₂And resistance R_FourThe second connection point is
While being connected to the trigger terminal of the constant oscillation circuit 7,
The output terminal of the monostable oscillator circuit 7 is the AND gate G₃
Is connected to the other end of the input terminal. This and gate
G₃Output terminal of the resistor R_FiveAnd R₆Through the series circuit of
While being connected to the source of the switching element SW,
Resistance R_FiveAnd R₆The connection point of the switching element SW is
Connected to the network.

Next, the operation of this circuit will be described with reference to FIG. A resonance voltage waveform obtained by dividing the drain-source voltage of the switching element SW as shown by the waveform A is applied to both ends of the resistor R ₂ . The applied voltage a is detected by the Zener diode ZD ₁ , and the signal phase of the portion where the Zener voltage V _ZD1 or more is present is the waveform B, which is input to the differentiation circuit composed of the capacitor C ₁ and the resistor R _3, and output. By the trigger signal C, the monostable oscillating circuit 6 is operated to output the output signal D of t _{1 which} is sufficiently shorter than the width of the output signal of B.

A signal E obtained by inverting this output signal D by an inverter gate G ₂ is input to a second differentiating circuit composed of a capacitor C ₂ and a resistor R _4, and the resulting trigger signal is fed to a monostable oscillator circuit 7. Input to the trigger terminal of and operate to obtain the output signal. The output signal G and the inverted signal of the waveform B are input to the AND gate G ₃ to obtain the output signal H. This signal H becomes an ON signal of the switching element SW. The signal shown in FIG. 4L is the ON signal of the switching element SW at the rated time.

According to the input power supply voltage V _E , the signal H is
When the on-duty changes and the input power supply voltage V _E is large, the on-duty becomes short, and the output voltage shifts to the low direction (d in FIG. 4). When the input power-supply voltage V _E is small, the on-duty becomes long and the output It is possible to control the output voltage to be constant by shifting the voltage in the higher direction (see FIG. 4).

[0023]

As described above, the present invention connects the DC power supply to one end of the primary winding of the transformer, connects the switching element to the other end of the primary winding of the transformer, and A capacitor is connected in parallel with the next winding or in parallel with the switching element, and a diode is connected to the secondary winding of the transformer in a direction in which a current flows when the switching element is turned on to light the incandescent lamp. The incandescent lamp lighting device is provided with an oscillating voltage time detection circuit that detects the time of the oscillating voltage applied to both ends of the switching element and is proportional to the magnitude of the DC power supply, and according to the magnitude of the output of the oscillating voltage time detecting circuit. Since a drive circuit that makes the output voltage of the switching element approximately constant is provided, when the oscillating voltage applied to both ends of the switching element is proportional to the magnitude of the DC power supply, Is detected, the output voltage of the switching element is made approximately constant according to the magnitude of the output of the oscillating voltage time detection circuit, and the fluctuation of the lamp voltage due to the fluctuation of the input power supply voltage is suppressed to keep the lamp voltage constant. It is possible to provide a high-quality lighting fixture without flicker, and a rated light output can be obtained at the rated input voltage, and the lamp life will not be impaired even at the upper limit of the input voltage. That is the effect.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention.

FIG. 2 is an operation waveform diagram of FIG. 1 above.

FIG. 3 is a circuit diagram of a second embodiment of the above.

FIG. 4 is an operation waveform diagram of FIG. 3 above.

FIG. 5 is a circuit diagram of a conventional example.

6 is an operation waveform diagram of FIG. 5 above.

7 is an operation waveform diagram of FIG. 5 above.

[Explanation of symbols]

 4 Drive circuit C Capacitor T Transformer D Diode L Lamp SW Switching element

Claims (1)

[Claims] 1. A DC power source is connected to one end of a primary winding of a transformer, a switching element is connected to the other end of the primary winding of the transformer, and in parallel with the primary winding of the transformer.
Alternatively, in the incandescent lamp lighting device, a capacitor is connected in parallel with a switching element, and a diode is connected to a secondary winding of a transformer in a direction in which a current flows when the switching element is turned on to light an incandescent lamp. Equipped with an oscillating voltage time detection circuit that detects the time of the oscillating voltage applied to both ends of the switching element and proportional to the magnitude of the DC power supply.The output voltage of the switching element can be adjusted according to the output of this oscillating voltage time detecting circuit. An incandescent lamp lighting device, which is provided with a drive circuit for making it constant.