JPH10125480A - Lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting device for making automatic lighting simultaneously with completion of exchange of a lamp on account of its cut without making power supply again in the case of a lighting device for rectifying AC power supply so as to convert it to high frequency AC by means of a high frequency conversion circuit to supply power to a lamp. SOLUTION: The article related to the present invention is a lighting device consisting of a dimming circuit 2 and a lighting circuit 1 and the latter of which is connected to a smoothing circuit (capacitors C1, C2) via a rectifier Re1 for rectifying AC power supply AC and diode D4 placed in connection from the plus side output of this rectifier Re1 in normal direction. High frequency power is supplied to a lamp load by placing a high frequency conversion circuit in connection from this smoothing circuit. The power supply of the starting circuit S of the high frequency conversion circuit is fed from the anode of the diode D4 so that it may not influenced by the smoothing circuit. Thereby, a full wave rectifying voltage having a zero-cross is impressed to the stating circuit S regardless of presence/absence of load, and simultaneously with exchange of the cut lamp, an inverter starts automatically to light the lamp.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device for lighting a lamp by rectifying an AC power supply voltage and converting it to high frequency power.

[0002]

2. Description of the Related Art FIG. 1 is an example of a circuit diagram of a conventionally used lighting device, which comprises a lighting circuit 1 and a dimming circuit 2.

The lighting circuit 1 comprises a rectifier Re1, a smoothing circuit, and a half-bridge type transistor inverter circuit. That is, a smoothing circuit composed of a series circuit of a pair of capacitors C1 and C2 and a switch circuit in which a pair of transistors Q1 and Q2 are connected in series via emitter resistors R1 and R2, respectively, are connected in parallel between the output terminals of the rectifier Re1. It is connected to the. Between the series circuit of each transistor Q1, Q2 and each emitter resistor R1, R2,
Recirculation diodes D1 and D2 are respectively connected in anti-parallel.

A primary winding of a step-down transformer T1 is connected between a connection point of the capacitors C1 and C2 of the smoothing circuit and a middle point of the switch circuit, that is, a connection point of the emitter resistor R1 of the transistor Q1 and the collector of the transistor Q2. And a series circuit of a primary winding of a feedback transformer T2 for driving the transistors Q1 and Q2.

A lamp LP as a load is connected to the secondary winding of the step-down transformer T1, and both ends of two sets of secondary windings of the feedback transformer T2 are connected to the respective transistors Q1 and Q2.
It is connected between the base of Q2 and the emitter resistors R1 and R2. Note that the two sets of secondary windings of the feedback transformer T2 are connected between the bases and the emitter resistors of the transistors Q1 and Q2 so that the phases are opposite to each other as shown by dots in the figure. A noise filter including a capacitor C4 and a common mode choke CH is provided in a stage preceding the rectifier Re1.

Further, the lighting circuit 1 is provided with a starting circuit S including a resistor R3, a capacitor C3, and a trigger element (SBS or the like) Q3. That is, the resistor R3 and the capacitor C3
Is connected between both ends of a smoothing circuit composed of a series circuit of capacitors C1 and C2.
When the voltage between both ends of C1 and C2 becomes equal to or higher than a predetermined voltage and the terminal of the capacitor C3 is charged via the resistor R3 to the breakover voltage of the trigger element Q3, the trigger element Q3 conducts and turns on the transistor Q2. It is configured as follows.

The diode D3 is provided to prevent charging of the capacitor C3 while the transistor Q2 is repeatedly turned on and off. When the oscillation of the inverter stops, the diode D3 is recharged. Is performed.

Accordingly, the starting circuit S turns on the trigger element Q3 only once and turns on the transistor Q2 initially at the time of starting the lighting circuit 1, that is, the high-frequency conversion circuit. Transistors Q1 and Q2 are alternately driven by two sets of secondary windings, and the inverter circuit continues to operate by self-excited oscillation.

On the other hand, the dimming circuit 2 for controlling the phase of the AC power supply AC is provided between the AC 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. The trigger circuit includes resistors R4 to R6, a capacitor C5, and 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 is turned on and the phase control element Q4 is turned on. The phase control element Q4
Is adjusted by the resistor R5.

Next, the operation of the lighting device will be described. First, when the phase control element Q4 of the dimming circuit 2 is turned on, the voltage of the AC power supply AC is full-wave rectified by the rectifier Re1, and the capacitors C1, C2 and C3 are charged. With the capacitors C1 and C2 of the smoothing circuit being charged, when the charged voltage of the capacitor C3 of the starting circuit S reaches the breakover voltage, the trigger element Q3 turns on. As a result, a base current flows through the transistor Q2, and the transistor Q2
2 is initially turned on. Then, the charge charged in the capacitor C2 is discharged through the route of the primary winding of the step-down transformer T1, the primary winding of the feedback transformer T2, and the transistor Q2.

As a result, a voltage is generated in one secondary winding of the feedback transformer T2 in a direction for forward-biasing the base of the transistor Q2, a base current flows, and the ON state of the transistor Q2 is continued. At this time, the base of the transistor Q1 is reverse-biased, and the transistor Q1 is off.

Eventually, the current flowing through the primary winding of the feedback transformer T2 settles down to the current limited by the equivalent resistance of the lamp LP, and the time derivative of the current change of the feedback transformer T2 becomes zero. The generated voltage of the secondary winding becomes zero. As a result, the base current of the transistor Q2 stops flowing, and the transistor Q2 is turned off.

When the current suddenly turns off, the feedback transformer T
Due to the inductance effect of 2, a voltage is generated in the other secondary winding so as to forward bias the base of the transistor Q1, and a base current flows to turn on the transistor Q1.

The electric charge accumulated in the capacitor C1 is transferred from the transistor Q1 to the primary winding of the feedback transformer T2.
It is discharged at the route of the primary winding of the step-down transformer T1. As a result, a voltage for forward-biasing the base of the transistor Q1 is generated in the other secondary winding of the feedback transformer T2,
The ON state of the transistor Q1 is continued.

This operation is repeated, and the self-excited oscillation operation of the inverter is performed. That is, the rectifier output voltage is converted into high-frequency AC, and the lamp LP is turned on by this high-frequency power.

[0017]

By the way, the starting circuit S for applying a trigger current to the transistor Q2 at the time of starting takes its power from the terminals of the capacitors C1 and C2 of the smoothing circuit. The capacities of the capacitors C1 and C2 of the smoothing circuit are set to be large enough to supply a load current for each half cycle of the inverter operation in terms of cost and size. Therefore, when a load current is supplied, the ripple component of the DC voltage of the smoothing circuit is as large as a full-wave rectified voltage having a zero cross. However, in the no-load state, the discharge from the capacitors C1 and C2 is small, and the DC voltage becomes a smooth pulsating flow with little ripple.

If the lamp suddenly burns out in the lamp load operating state, the voltage of the smoothing circuit is applied to the starting circuit S as a DC voltage having a small ripple. When the trigger element Q3 of the activation circuit S is turned on by the breakover voltage, the trigger element Q3 continues to be turned on by the holding current of the DC voltage from the smoothing circuit. That is, the starting circuit S
Is set to a value that can supply a base current sufficient to turn on the transistor Q2.
Of course, when the pulsating voltage is applied, the base current is the trigger element Q3
, The trigger element Q3 remains in the ON state.

For this reason, the secondary winding of the feedback transformer T2 on the driving side of the transistor Q2 keeps the DC current flowing through the trigger element Q3, and this secondary winding remains clamped to almost zero impedance. State.

Even if a new lamp is installed in this state,
The feedback transformer T2 does not generate a voltage, so that the high frequency conversion circuit does not oscillate and the lamp does not light.

At this time, in order to turn on a new lamp, it is necessary to temporarily turn off the AC power, return the trigger element Q3 to the off state, and then restart it. Particularly, many lamps such as commercial facilities are used. In places where it is used, it is inconvenient to turn off the power and turn off all lamps each time one lamp is burned out and replaced.

Accordingly, an object of the present invention is to provide a lighting device which rectifies a commercial AC power supply, converts it into high-frequency AC power, and supplies it to a lamp. If the lamp burns out and is replaced with a new lamp, the power supply is reset. Even if it is not, a new lamp is automatically turned on.

[0023]

SUMMARY OF THE INVENTION The present invention provides a rectifier having an AC power supply as an input, a smoothing circuit for smoothing the output of the rectifier, a high frequency conversion circuit for converting the output of the smoothing circuit to a high frequency AC, and a high frequency conversion circuit. A lamp load connected to the output of the circuit, comprising a starting circuit for receiving a full-wave rectified voltage before the output voltage of the rectifier is smoothed and starting a high-frequency conversion circuit. I will provide a.

The lighting device of the present invention rectifies an AC voltage with a rectifier, converts a DC voltage passed through a smoothing circuit into a high-frequency AC by a high-frequency conversion circuit including, for example, a transistor inverter, and supplies the high-frequency AC to the lamp. Turn on the lamp. Here, the starting circuit for starting the high-frequency conversion circuit is supplied with power from the output terminal of the rectifier, that is, the input terminal of the smoothing circuit. Therefore, the voltage supplied to the start-up circuit always has a rectified waveform having a zero-cross point before smoothing, regardless of whether the load is applied or not, so that the start-up circuit is always turned off near the zero cross in each cycle. Therefore, even when there is no load due to the lamp running out, a state similar to that of power reset is given to the lighting device at the time of passing the zero cross point, and when a new lamp is attached, the high frequency conversion circuit is automatically restarted and the lamp is turned on. .

In a preferred embodiment of the lighting device of the present invention,
A diode is inserted between the rectifier and the smoothing circuit in the forward direction, and the anode of the diode is connected to the input of the starting circuit. This diode prevents the output voltage of the rectifier from being affected by the smoothing circuit. Further, in this preferred embodiment, the starting circuit includes a capacitor charged by the full-wave rectified voltage of the rectifier, and a trigger element that breaks over by the charged voltage of the capacitor and starts the high-frequency conversion circuit. .

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below based on embodiments. FIG. 2 is a circuit diagram of a lamp lighting device according to one embodiment of the present invention. The same parts as those in the conventional example shown in FIG. 1 are denoted by the same reference numerals, and duplicate description will be omitted.

As shown in FIG. 2, the basic configuration of this embodiment, that is, a dimming circuit 2 for controlling the phase of an AC power supply AC by a phase control element Q4, and rectifying an AC voltage controlled by the dimming circuit 2 1 and a lighting circuit 1 which converts the high-frequency AC into a high-frequency AC by a half-bridge transistor inverter and supplies the high-frequency AC to a lamp LP through a smoothing circuit.

Here, in order to explain the principle of the present invention,
The role of the capacitors C1 and C2 of the smoothing circuit will be described briefly. Since the high-frequency conversion circuit is a half-bridge type transistor inverter, it is necessary to supply the input power of the inverter by dividing the voltage of the rectifier Re1 into two. Therefore, a capacitor C of the same capacitance is connected between the output terminals of the rectifier Re1.
1 and C2 are connected in parallel, and the capacitors C1 and C2 are used as power supplies for every half cycle of the inverter operation.

Therefore, the capacity of these capacitors needs to be large enough to supply a load current every half cycle of the inverter operation, but the characteristics are satisfied in terms of the size and cost of the device. It is desirable to be as small as possible within the range. Therefore, when the inverter is in load operation, the voltage between the smoothing circuit terminals (the voltage at the C1 and C2 terminals)
Has a large ripple component.

FIG. 3 shows voltage waveforms between the smoothing circuit terminals when the load is applied and when no load is applied. When the lamp is lit, the waveform becomes a full-wave rectified waveform having a zero cross as in the rectifier output terminal as shown in FIG. However, when there is no load,
Since only a weak current such as the current to the starting circuit S flows,
As shown in (b), the ripple voltage has a small ripple component.

Therefore, in the prior art shown in FIG. 1, when no load is applied, a pulsating voltage as shown in (b) is applied to the input terminal of the starting circuit S, and the trigger element Q3 is always turned on by the holding current. Become. Therefore, one of the feedback transformer T2 2
As described above, since the next winding is clamped at zero impedance, it cannot be automatically restarted even if a load is connected.

FIG. 2 is a circuit diagram of a lamp lighting device according to a preferred embodiment of the present invention for solving this problem. One feature of this embodiment on a circuit different from the conventional device is that a rectifier Re1 and a smoothing circuit (capacitors C1, C
Between 2) and the direction of charging the capacitor (forward direction)
Is that a diode D4 is inserted in the first embodiment. The input terminal of the starting circuit S (the inflow side of the resistor R3) is connected to the anode side of the diode D4, that is, the positive output terminal of the rectifier Re1.

As a result, since the output terminal voltage of the rectifier Re1 is blocked by the diode D4 and is not affected by the smoothing circuit, the full-wave rectification having a zero cross as shown in FIG. It becomes a waveform. Therefore, a full-wave rectified voltage having a zero cross as shown in FIG. 3A is applied to the input of the starting circuit S even when there is no load.

The process of automatically turning on the lamp after the bulb has been replaced by applying a voltage waveform having such a zero cross to the starting circuit S will be described in detail with reference to the drawings.

FIG. 4 shows waveforms of respective parts showing operation modes before and after lamp replacement. (A) shows the state of the lamp,
(B) shows the applied voltage of the starting circuit S, (c) shows the operating state of the trigger element Q3 that controls the starting of the inverter, and the horizontal axis shows the passage of time.

First, when the lamp is turned on, the transistor Q
1, since Q2 performs an inverter operation, the charge of the capacitor C3 is discharged from the diode D3 through the transistor Q2, and the voltage applied to the trigger element Q3 is the breakover voltage regardless of the applied voltage (b) of the starting circuit S. Does not reach. Therefore, as shown in (c), the trigger element Q3 keeps the off state. Therefore, the transistors Q1,
Q2 repeats on and off operations by the feedback transformer T2.

Assume that the lamp burns out at time t1 while the lamp LP is turned on by the inverter operation as shown in FIG. At this time, as shown in (b), the applied voltage of the starting circuit S does not change before and after the lamp has run out, and has a full-wave rectified waveform having a zero cross.

On the other hand, when the lamp has run out, the transistor Q
1, since the current of Q2 does not flow, the capacitor C3 is not discharged through the diode D3. Therefore, the capacitor C3 is charged by the applied voltage (b) of the starting circuit S. Therefore, if the full-wave rectified voltage applied to the starting circuit S at the time when the lamp has run out is equal to or higher than the breakover voltage of the trigger element Q3, the trigger element Q3 is turned on as shown in (c). For this reason, one secondary winding of the feedback transformer T2 is clamped to zero impedance, and there is no base current to the inverter, so that the inverter is stopped.

Then, the applied voltage (b) of the starting circuit S becomes
At time t2 near the zero-crossing point of the full-wave rectified waveform, the trigger element Q3 becomes equal to or lower than the holding current, and the trigger element Q3 is turned off. Becomes

Then, at time t3 when the applied voltage (b) of the starting circuit S has passed the zero crossing and reached the breakover voltage in the next cycle, the trigger element Q3 is turned on again, and the starting trigger is applied to the transistor Q2. However, if the lamp has been out, the current does not flow through the transistor Q2, so that the capacitor C3 does not discharge, and the trigger element Q3 keeps the on state until near the next zero cross due to the holding current. Therefore, one secondary winding of the feedback transformer T2 is clamped at zero impedance, and the inverter does not operate.

As described above, even in the no-load state, the start trigger is applied near the zero crossing every half-wave of the full-wave rectified waveform. However, the feedback transformer T2 does not operate while the lamp burns out continuously, and the inverter is not operated. It remains off.

If it is assumed that the lamp is replaced with a new lamp at time t4, the time t5 near the first zero crossing thereafter is changed.
As a result, the trigger element Q3 is turned off, and the feedback transformer T2 can be excited.

Eventually, the applied voltage (b) of the starting circuit S becomes
At time t6 when the breakover voltage of the next cycle is reached from zero crossing, the trigger element Q3 is turned on, and a start trigger is applied to the transistor Q2. At this time, since the lamp current starts to flow, the feedback transformer T2 supplies the base current through its secondary winding, and the inverter starts operating by self-excited oscillation.

Since the lamp load current flows through the transistor Q2, the electric charge of the capacitor C3 is discharged from the diode D3 through the transistor Q2, and the capacitor C3 is discharged.
Does not reach the breakover voltage, and the trigger element Q3 remains off. Therefore, the feedback transformer T
Since 2 is always in an excited state, the inverter operates by self-excited oscillation and the lamp continues to light.

In this way, even if the lamp has run out, a start trigger is automatically applied to the inverter after the lamp is replaced, so that the lamp is automatically turned on when the lamp is replaced.

In this embodiment, the lighting device for lighting a lamp by a half-bridge type transistor inverter has been described. However, as long as the lighting device is operated by high-frequency AC, the lamp is not limited to an incandescent lamp or a fluorescent lamp. . Further, the high-frequency conversion circuit is not limited to a half-bridge type inverter, but may be a full-bridge inverter or another high-frequency conversion circuit using a semiconductor switch. In this way, it goes without saying that the lighting device of the present invention can be realized using any high-frequency conversion circuit.

In the above-described embodiment, the case where the phase control element Q4 of the dimming circuit 2 is fully conductive has been described. However, even when dimming is performed by phase control, automatic lighting can be performed similarly. Can be done. Further, the AC power supply AC is not limited to a commercial power supply, and may be an AC generator or the like.

[0048]

According to the present invention, a lamp such as a fluorescent lamp can be efficiently used.
In addition, a high-frequency conversion circuit such as an inverter of several KHz or more is used for a lighting device for lighting while preventing flickering. This high-frequency conversion circuit generally requires a starting circuit, but according to the present invention, even if the power is not turned on again at the time of lamp burnout replacement, the operation of the starting circuit automatically turns on the lamp at the same time as the completion of replacement. Can be done. For conventional lighting devices,
For example, this can be realized only by adding one diode, so that it is possible to provide an easy-to-use lighting device that hardly increases the cost.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a lamp lighting device according to a conventional example.

FIG. 2 is a circuit diagram of a lamp lighting device according to one embodiment of the present invention.

FIG. 3 shows voltage waveforms between smoothing circuit terminals under load and no load.

FIG. 4 is a waveform chart showing operation modes before and after lamp replacement.

[Explanation of symbols]

 Reference Signs List 1 lighting circuit 2 dimming circuit S starting circuit Re1 rectifier LP lamp R1 to R6 resistor C1 to C5 capacitor D1 to D4 diode Q1, Q2 transistor Q3, Q5 trigger element Q4 phase control element CH common mode choke T1 step-down transformer T2 feedback transformer AC AC source

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Nobuhiro Goto 2-1-1 Nakajima, Kokurakita-ku, Kitakyushu-shi, Fukuoka Touchi Kiki Co., Ltd. (72) Inventor Yuji Kusakabe 1-chome, Showacho, Tondabayashi-shi, Osaka No. 27 Inside Mioka Electric Works

Claims (3)

[Claims] 1. A rectifier having an input of an AC power supply, a smoothing circuit for smoothing an output of the rectifier, a high-frequency conversion circuit for converting an output of the smoothing circuit into a high-frequency AC, and an output of the high-frequency conversion circuit. And a starting circuit that receives the full-wave rectified voltage before the output voltage of the rectifier is smoothed and starts the high-frequency conversion circuit. Lighting device. 2. The lighting device according to claim 1, wherein a diode is inserted between the rectifier and the smoothing circuit in a forward direction, and an anode of the diode is connected to an input of the starting circuit. Lighting device. 3. The lighting device according to claim 1, wherein the starting circuit breaks over by a capacitor charged by a full-wave rectified voltage of the rectifier and a charging voltage of the capacitor. And a trigger element for activating the high-frequency conversion circuit.