JPH08264284A - Lighting device - Google Patents

Abstract

PURPOSE: To light a lamp such as an incandescent lamp by converting a commercial power supply voltage into a high frequency. CONSTITUTION: A lighting device is composed of a dimming circuit 2 which phase-controls a commercial power supply voltage by a phase control element Q4, and a lighting circuit 1 which rectifies the output of the dimming circuit 2 by a rectifier Re so as to convert it into a high frequency by a half bridge type transistor inverter to feed electricity to an incandescent lamp LP. The lighting circuit 1 is equipped with a starting circuit S which starts the transistor inverter when the phase control element Q4 is turned on. The starting circuit S is equipped with a resistor 3 which adjusts an input current to a trigger element Q3, a capacitor C3 which is charged through the resistor R3 at every half wave of the power supply, and the trigger element Q3 which is turned on by the charge voltage of the capacitor C3. In order to shorten the charge time of the capacitor C3 when the phase control element Q4 is turned on, a series circuit of a resistor R7 of a small resistant value and a DC cutting capacitor C6 is provided in parallel to the resistor R3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device which converts a commercial power supply voltage into a high frequency and lights a lamp such as an incandescent lamp with the high frequency power.

[0002]

2. Description of the Related Art FIG. 3 is a circuit diagram of a conventional incandescent lamp lighting device.

The incandescent lamp lighting device comprises a lighting circuit 1 and a dimming circuit 2.

The lighting circuit 1 is composed of a rectifier Re and a half-bridge type transistor inverter circuit. That is, between the output terminals of the rectifier Re, a pair of transistors Q1 and Q2, which are switching elements, and the respective transistors Q1 and Q2.
Pair of resistors R1 and R2 connected to the emitters of
And a series circuit of a pair of capacitors C1 and C2 are connected in parallel. Freewheeling diodes D1 and D2 are respectively connected in antiparallel to the series circuit of the transistors Q1 and Q2 and the resistors R1 and R2. A step-down transformer T is provided between the connection point between the capacitors C1 and C2 and the connection point between the resistor R1 and the collector of the transistor Q2.
A series circuit of the primary winding of No. 1 and the primary winding of the feedback transformer T2 is connected.

An incandescent lamp (lamp) LP is connected to the secondary winding of the step-down transformer T1, and both ends of a pair of secondary windings of the feedback transformer T2 are respectively connected to the base-emitters of the transistors Q1 and Q2 and the resistors R1. , R2 are connected across the series circuit. Further, both secondary windings of the feedback transformer T2 are connected to the transistors Q1 and Q2 so as to have mutually opposite phases. A noise filter including a capacitor C4 and a choke coil CH is provided in front of the rectifier Re.

Further, the lighting circuit 1 is provided with a starting circuit S which is composed of a resistor R3, a capacitor C3, and a trigger element (SBS or the like) Q3. That is, the resistor R3 and the capacitor C
3 is connected between both ends of the series circuit of the capacitors C1 and C2, the voltage between both ends of the capacitors C1 and C2 becomes a predetermined voltage or more, and the terminal of the capacitor C3 is connected to the trigger element Q3 via the resistor R3. When it is charged up to the breakover voltage of the above, the trigger element Q3 becomes conductive and turns on the transistor Q2.

The diode D3 is a transistor Q.
2 is provided to prevent the capacitor C3 from being charged while it is repeatedly turned on and off. When the oscillation operation is stopped, the capacitor C3 is recharged.

On the other hand, the dimming circuit 2 for controlling the phase of the commercial power supply AC is provided between the commercial power supply AC and the lighting circuit 1, and turns on the phase control element Q4 such as a triac and the phase control element Q4. And a trigger circuit for causing the trigger circuit to include resistors R4 to R6, a capacitor C5,
It is composed of a trigger element Q5.

When the capacitor C5 is charged and the terminal voltage reaches the breakover voltage of the trigger element Q5, the trigger element Q5 becomes conductive and the phase control element Q4 is turned on. The phase control element Q
The firing angle of 4 is adjusted by the resistor R5.

Next, the operation will be described.

When the phase control element Q4 of the dimming circuit 2 is turned on, the AC power supply voltage is full-wave rectified by the rectifier Re,
The capacitors C1, C2 and C3 are charged. When the capacitors C1 and C2 are charged, the transistor Q is activated by the starting circuit S (according to the charging voltage of the capacitor C3).
When 2 is activated (turned on), the electric charge charged in the capacitor C2 is discharged through the path of the primary winding of the step-down transformer T1 → the primary winding of the feedback transformer T2 → the transistor Q2.

At this time, a current flows in the secondary winding of the feedback transformer T2 in the direction for forward biasing the transistor Q2 (thus, the transistor Q1 is reverse biased and turned off). After that, the current flowing through the primary winding of the feedback transformer T2 is limited to the current equivalent to the equivalent resistance of the incandescent lamp LP, the current does not flow through the secondary winding of the feedback transformer T2, and the transistor Q2 is turned off. I will be heading. Therefore, a current that reverse-biases the transistor Q2 and forward-biases the transistor Q1 flows in the secondary winding of the feedback transformer T2, and as a result, the transistor Q1 is turned on and the charge accumulated in the capacitor C1 is charged. Are discharged through the path of the transistor Q1 → the primary winding of the feedback transformer T2 → the step-down transformer T1.

This operation is repeated to perform the oscillating operation. That is, the pulsating flow output from the rectifier Re is converted into high frequency, and the high frequency power is used to turn on the incandescent lamp LP.

[0014]

By the way, the resistor R3
Is an input current limiting resistance of the trigger element Q3, and it is necessary to select one having a large resistance value. Further, the capacitor C3 needs to have a time constant that can secure a time for which the transistor Q2 activated by the breakover of the trigger element Q3 can be sufficiently turned on. Further, the capacitor C3 has a capacitance enough to store the charge enough to break the trigger element Q3. There is a need to.

Conventionally, a large time constant circuit composed of a resistor R3 and a capacitor C3 selected with such an intention,
Since the capacitor C3 is charged, the delay time from the turn-on of the phase control element Q4 to the activation circuit S activating the transistor Q2 becomes long. Then, during this delay time, there is a problem that the rush current of the incandescent lamp lighting circuit largely changes and becomes an oscillating current, and the phase control element Q4 is turned off near the zero cross of the oscillating current, causing flicker.

The present invention has been made in view of such a background, and an object of the present invention is to start the start-up circuit immediately after the phase control element of the dimming circuit is turned on to cause the oscillation of the input current. An object of the present invention is to provide a lighting device that can suppress and perform stable dimming.

[0017]

In order to achieve the above object, the present invention provides a high frequency conversion circuit for converting an AC power supply into a high frequency and supplying it to a lamp, and a high frequency conversion circuit for each half wave of the AC power supply. In a lighting device including a starting circuit for starting, the starting circuit starts a high frequency conversion circuit by being turned on by a capacitor charging circuit that receives each half wave of an AC power source to charge a capacitor and a charging voltage of the capacitor charging circuit. The present invention is characterized by having a trigger element and a time constant adjusting circuit that reduces the charging time constant of the capacitor at the initial stage of charging the capacitor.

In a preferred embodiment, the capacitor charging circuit has a capacitor for turning on the trigger element and a first resistor connected in series with the capacitor for limiting the input current of the trigger element, the time constant The adjustment circuit has a second resistor having a resistance value smaller than that of the first resistor, and a DC cut capacitor connected in series to the second resistor, and the second resistor and the DC cut capacitor are connected in series. The body is connected in parallel with the first resistor.

[0019]

In the present invention, when a half wave of the power supply voltage is applied to the starting circuit, the capacitor is charged, and when the charging voltage reaches the breakover voltage of the trigger element, the high frequency converting circuit is started. At that time, the initial charging time constant of the capacitor initially applied with the half wave is lowered by the time constant adjusting circuit, so that the charging of the capacitor is accelerated and the charging voltage quickly reaches the breakover voltage. Therefore, when a dimming circuit is provided on the input side of this lighting device and the power supply is phase-controlled by the phase control element, when the phase control element turns on and a half wave of the power supply is added to the starting circuit, the capacitor is quickly Is charged, the trigger element is immediately turned on, and the high frequency conversion operation is activated.

Therefore, the delay time from the turn-on of the phase control element to the turn-on of the trigger element is shortened, the generation of oscillating current is suppressed, and the flicker of the lamp is reduced.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. The same parts as those in the conventional example shown in FIG. 3 are denoted by the same reference numerals, and duplicate description will be omitted.

FIG. 1 is a circuit diagram of an incandescent lamp lighting device according to an embodiment of the present invention.

As shown in FIG. 1, the basic configuration of the apparatus of this embodiment, that is, a dimming circuit 2 of a type in which the phase control element Q4 is conducted at an arbitrary phase of the commercial power supply AC, and the dimming circuit 2 are passed. The basic configuration including the lighting circuit 1 which rectifies the commercial power supply voltage and converts it into a high frequency by a half-bridge type transistor inverter and supplies it to the incandescent lamp LP is the same as that of the conventional device shown in FIG.

The structural feature of the device of this embodiment, which is different from that of the conventional device, is the starting circuit S in the lighting circuit 1. That is,
It has a resistance value smaller than the resistance R3 (first resistance) so as to turn on the trigger element Q3 immediately after the phase control element Q4 of the dimming circuit 2 is turned on by shortening the charging time to the capacitor C3 as much as possible. Resistance R7 (second resistance)
Are provided in series with the capacitor C3 and in parallel with the resistor R3.

Further, a capacitor C6 for cutting direct current
Is added in series to the second resistor R7. The capacitor C6 is for preventing the second resistor R7 from affecting the amount of input current to the trigger element Q3.

The constants of the first resistor R3 and the capacitor C3 are determined with the same intention as that of the conventional starting circuit shown in FIG. That is, as described above, the resistance value of the first resistor R3 is the input current limiting resistor of the trigger element Q3, and is selected to be large enough to achieve this purpose. The capacitance of the capacitor C3 is the same as that of the transistor Q2 activated by the breakover of the trigger element Q3.
Has a time constant capable of ensuring a sufficient ON time, and is selected as a capacitance value capable of accumulating sufficient electric charge to sufficiently break over the trigger element Q3.

FIG. 2 is an explanatory diagram showing the start timing of the trigger element Q3 and the charge / discharge characteristics of the capacitor C3 of this embodiment in comparison with the conventional example of FIG.

In this figure, the characteristic indicated by the broken line indicates the conventional example, and the characteristic indicated by the solid line indicates the present embodiment. The vertical axis represents the charging voltage E of the capacitor C3, and E1 represents the breakover voltage of the trigger element Q3. The horizontal axis represents time, of which t0 is the turn-on timing of the phase control element Q4 of the dimming circuit 2, t1 is the trigger element conduction timing of the present embodiment, and t2 is the conventional trigger element conduction timing. ing.

As shown in this figure, immediately after the phase control element Q4 is turned on, a resistor R7 having a small resistance value is mainly used.
Since the electric charge is instantly stored in the capacitor C3 through the capacitor C6, the timing t1 at which the trigger element Q3 breaks over is significantly earlier than the conventional timing t2. As a result, after the phase control element Q4 is turned on, the starting circuit S is quickly started, the transistor Q2 is turned on, and high-frequency oscillation is started, so that the oscillation of the input current is suppressed. Therefore, stable dimming of the incandescent lamp LP without flicker becomes possible.

The trigger element Q3 is connected via the resistor R7.
After the capacitor C3 is rapidly charged to the vicinity of the breakover voltage, the electric charge is supplied to the capacitor C3 through the resistor R3 and the trigger element Q3 is maintained in the ON state until the power supply voltage decreases. At this time, the electric charge of the capacitor C6 is saturated, and no current flows through the path of the resistor R7 and the capacitor C6.

Although the incandescent lamp lighting device has been described as an example, the present invention can be applied to a lamp lighting device other than the incandescent lamp.

[0032]

As described above, according to the present invention,
It is possible to provide a highly reliable lighting device capable of preventing flickering of a lamp even when a dimming circuit is connected.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an incandescent lamp lighting device according to an embodiment of the present invention.

FIG. 2 is a comparative explanatory diagram showing the activation timing of the trigger element and the charge / discharge characteristics of the capacitor.

FIG. 3 is a circuit diagram of an incandescent lamp lighting device according to a conventional example.

[Explanation of symbols]

 1 Lighting circuit 2 Dimming circuit S Start circuit R3, R7 Resistance C3, C6 Capacitor Q3 Trigger element Q4 Phase control element LP Incandescent lamp Re Rectifier

Front page continuation (72) Inventor Takahiro Michiya Nakajima 2-1-1 1-1 Kokurakita-ku, Kitakyushu, Fukuoka Prefecture Totoki Equipment Co., Ltd. (72) Inventor Tadashi Akashi 3--18-16 Negishi, Taito-ku, Tokyo Tokyo Torance Co., Ltd.

Claims (2)

[Claims] 1. A lighting device comprising: a high frequency conversion circuit for converting an AC power supply into a high frequency and supplying the high frequency to a lamp; However, a capacitor charging circuit that receives a half wave of the AC power source to charge a capacitor, a trigger element that is turned on by a charging voltage of the capacitor charging circuit to activate the high frequency conversion circuit, and the initial charging of the capacitor A lighting device, comprising: a time constant adjusting circuit for reducing a charging time constant of a capacitor. 2. The device according to claim 1, wherein the capacitor charging circuit has the capacitor and a first resistor connected in series with the capacitor to limit an input current of the trigger element, The constant adjustment circuit includes a second resistor having a resistance value smaller than that of the first resistor and a DC cut capacitor connected in series to the second resistor, and the second resistor and the DC cut capacitor. A lighting device characterized in that a series connection body with is connected in parallel with the first resistor.