JP2001167892A - Discharge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device that prevents generation of noise by controlling inrushing current and is stopped in an abnormal state of lamp or power. SOLUTION: The discharge lamp lighting device comprises a discharge lamp 12 having a pair of electrodes at inner portion, switch circuit 15 being connected to a power source 11, an inverter circuit 13, and detecting circuit 14 for detecting a state of the lamp. The switch circuit 15 has common switching elements 10 being connected between the power source 11 and the inverter circuit 13 and turning on or off a connection of the power source 11 and the inverter circuit 13 according to on/off of push switches 1, 3 or state of lamp detected by the detecting circuit 14, and time constant circuit being connected to the common switching elements 10 and for connecting the power source 11 having predetermined time constant and the inverter circuit 13 at the introduction of power.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device.

[0002]

2. Description of the Related Art Heretofore, as a lighting circuit of a discharge lamp, for example, a circuit using an inverter circuit for boosting a DC power source such as a battery and lighting the discharge lamp with DC has been known.

By the way, such an inverter circuit is
Although a smoothing capacitor is used to absorb fluctuations in the input voltage, when the power is turned on, the charge of this smoothing capacitor is empty, and an inrush current several tens of times that in a steady state is generated by the inverter circuit. Flow into Therefore, a large noise is generated when the power is turned on, which may affect other devices. For this reason, it is necessary to use a switch having a large capacity as a switch for connecting / disconnecting the power supply and the inverter circuit.

A circuit using a thermistor, a triac, or the like as shown in FIG. 2 is known to suppress such an inrush current and prevent generation of a large noise (Japanese Patent Laid-Open No. 9-163593).

In the thermistor system, the rush current can be suppressed immediately after the power is turned on because the resistance of the negative characteristic thermistor (PTC) is high. be able to. In the triac method, the inrush current can be suppressed by gradually increasing the phase angle.

[0006]

However, in the thermistor method, since the self-heating of the PTC is used, the current suppressing effect cannot be expected until the temperature of the PTC decreases in the case of restart, and in the triac method, There is a problem in that a control circuit is separately required, and moreover, a large amount of noise is generated.

Further, since the discharge lamp is used as the load, it is necessary to safely stop the operation of the lighting circuit according to the lamp state in order to prevent the discharge lamp from exploding at the end of the lamp life.

Further, a lighting device used for a flashlight using a discharge lamp as a light source should desirably have a simple configuration which solves the above-mentioned problem and has as few parts as possible.
In addition, since the lamp is used outdoors, the lamp characteristics are likely to fluctuate due to the outside air temperature, and the lamp characteristics are likely to change due to damage or leakage of the lamp due to impact. A protection circuit for protection and protection of the human body from electric shock or the like is required.

The present invention has a simple structure which can suppress an inrush current and prevent generation of a large noise, detect an abnormality of a lamp or an abnormality of a power supply, and stop the operation of a lighting circuit. It is an object of the present invention to obtain a suitable discharge lamp lighting device.

[0010]

A discharge lamp lighting device according to the present invention includes a discharge lamp having a pair of electrodes therein, a switch circuit to be connected to a power supply, an inverter circuit,
A detection circuit for detecting a lamp state, wherein the switch circuit is connected between the power supply and the inverter circuit, and the On / Off state of a push switch or the state of the lamp detected by the detection circuit, A common switching element for turning on / off the connection between a power supply and the inverter circuit; and a time constant circuit connected to the switching element for connecting the power supply and the inverter circuit with a predetermined time constant when the power is turned on. And

[0011] Thus, the rush current can be suppressed to prevent the generation of large noise, and the operation of the lighting circuit can be stopped by detecting the state of the lamp or the abnormality of the power supply, and has a simple and safe structure. It is an object to obtain a discharge lamp lighting device.

[0012]

Embodiments of the present invention will be described with reference to the drawings.

As shown in FIG. 1, a discharge lamp lighting device for a flashlight having a discharge lamp as a light source according to an embodiment of the present invention has a pair of electrodes inside, and has mercury and metal inside. Discharge lamp 12 filled with iodide gas
A switch circuit 15 to be connected to the power supply;
An inverter circuit 13 that boosts the pressure from 1 to light the discharge lamp 12 and a detection circuit 14 that detects the lamp state are provided.

The switch circuit 15 is connected between the power supply 11 and the inverter circuit 13 and includes push switches 1, 3.
Is connected to the common switching element 10 for turning on / off the connection between the power supply 11 and the inverter circuit 13 according to the On / Off state of the discharge lamp 12 or the state of the discharge lamp 12 detected by the detection circuit 14,
When the power is turned on, a time constant circuit including a resistor 6 and a capacitor 9 for connecting the power supply 11 and the inverter circuit 13 with a predetermined time constant is provided.

The detection circuit 14 detects the lamp state from the lamp voltage, and outputs an "H" level signal when an abnormality occurs.

The power supply 11 is connected to an inverter circuit 13 through a switch circuit 15.

The output of the inverter circuit 13 includes a lamp 12
And a series circuit of resistors 25 and 26 is connected to both ends of the lamp 12.

The connection point between the resistors 25 and 26 is the detection circuit 1
4, the detection circuit 14 outputs a signal corresponding to the input voltage to the switch circuit 15.

Here, the configuration of each circuit will be described.

The detection circuit 14 receives a lamp voltage divided by a series circuit composed of a resistor 25 and a resistor 26 connected to both ends of the lamp 12 through a diode 16 and an operational amplifier 17.
And the negative side of the operational amplifier 18.

A capacitor 21 is provided on the + side of the operational amplifier 17.
Is connected, and as the lamp voltage increases, the potential of the capacitor 21 increases accordingly. Operational amplifier 1
7 is the potential of the capacitor 21 and the reference voltage 19
And outputs an “H” level when the reference voltage 19 is exceeded. This output is fed back to the input of the operational amplifier 17, and once the output goes to the "H" level, that state is maintained.

Here, the diode 24 has a function of preventing the input to the operational amplifier 17 from being directly output to the output of the detection circuit 14 through the feedback route.

Similarly, the operational amplifier 18 compares the ramp voltage divided by a series circuit composed of a resistor 25 and a resistor 26 connected to both ends of the input lamp 12 with a reference voltage 20, and the reference voltage 20 or less. , An “H” level is output.

The output of the operational amplifier 18 is gradually increased by a time constant circuit constituted by the resistor 22 and the capacitor 21. When the potential of the capacitor 21 continues to rise for a certain period of time and exceeds the voltage of the reference voltage 19, the operational amplifier 17 operates to output and hold an “H” level signal.

As described above, the detection circuit 14 has a function of outputting the "H" level when the input voltage becomes a value other than an appropriate voltage, and holding the state.

Next, the power supply 11 is connected to the switch circuit 15.
The switching element 10 is inserted between the power supply 11 and the inverter circuit 13 in accordance with the potential of the gate.

At start-up, the push switch (ON switch) 1 is turned on, so that the push switch 1
A voltage is applied to the gate of the switching element 10 through the resistors 2 and 6, and the switching element 10 is turned on.
When the switching element 10 is turned on and the power supply 11 is connected to the inverter circuit 13, the output of the detection circuit 14, that is, the output of the operational amplifier 17 becomes “L” level.
State and the push switch 1 is in the OFF state, the capacitor 9 is connected through the switching element 4, the resistor 5, and the resistor 6.
Continue to supply charge to As a result, the switching element 10 can maintain the On state.

Here, a Zener diode 23 is inserted between the output of the detection circuit 14 and the input of the switch circuit 15, and the potential difference between both ends of the Zener diode 23 becomes less than the Zener voltage due to fluctuations in the power supply voltage and the like. In this case, since the switching element 4 cannot be held in the On state through the Zener diode 23, the switching element 10 is turned off, and the power supply 11 and the inverter circuit 13 are disconnected.

Further, a time constant circuit comprising a resistor 6 and a capacitor 9 is connected to the gate of the switching element 10, and the current flowing into the inverter circuit 13 rises gradually according to the time constant.

Subsequently, when the push switch (OFF switch) 3 is turned on, the push switch 3
The charge of the capacitor 9 is discharged through the resistor 6 and the resistor 6.
When the current starts flowing through the switching element 7, the switching element 7 is turned on. Thereafter, even if the push switch 3 is turned off, the charge of the capacitor 9 is immediately discharged through the switching element 7, so that the switching element 10
ff state, and the operation of the inverter circuit 13 stops.

When an "H" level signal is input to the switch circuit 15 from the detection circuit, the switching element 4 is turned off. For this reason, the electric charge of the capacitor 9 is discharged through the resistors 6 and 8, and similarly, the switching element 7 is turned on. As a result, the charge of the capacitor 9 is rapidly discharged through the switching element 7, the switching element 10 is turned off, and the connection between the power supply 11 and the inverter circuit 13 is released.

Next, the operation will be described.

The lamp 12 is turned on by the push switch 1.

When the push switch 1 is pressed, the switching element 10 is turned on, and the power supply 11 and the inverter circuit 13 are connected.

Here, the connection between the power supply 11 and the inverter circuit 13 is made gently by the time constant circuit of the resistor 6 and the capacitor 9 described above, whereby the rush current flowing into the inverter circuit 13 when the power is turned on can be suppressed. .

When the power supply 11 and the inverter circuit 13 are connected and the lamp is normally lit, the output of the detection circuit 14 becomes "L" level, and the switching element 4 in the switch circuit 15 is turned on. As a result, even when the push switch 1 is off, the power supply 11 and the inverter circuit 13
Connection is maintained, and the lamp remains lit.

The push switch 3 is used to release the connection between the held power supply 11 and the inverter circuit 13.

When the push switch 3 is turned on, the electric charge stored in the capacitor 9 is discharged through the push switch 3 or the switching element 7.
The switching element 10 is immediately turned off, and the lamp is turned off.

Also, when the lamp 12 is abnormal, the connection between the power supply 11 and the inverter circuit 13 is released by the detection circuit 14.

When the discharge characteristics deteriorate, such as at the end of the lamp life, the lamp voltage increases. The detection circuit 14 detects this voltage rise and outputs an “H” level signal to the switch circuit 15.

When the pressure in the lamp is reduced due to a defective sealing of the lamp and the lamp voltage is lowered, the detecting circuit 14 detects this voltage drop and outputs an "H" level signal to the switch circuit 15. .

Here, the signal (output of the operational amplifier 18) that detects the decrease in the lamp voltage is supplied to the resistor 22 and the capacitor 21.
Is connected to the operational amplifier 17 via a time constant circuit composed of

Even if the lamp is normal, the lamp voltage is not sufficiently increased immediately after the start because the lamp temperature is low, and the detection circuit 14 does not erroneously recognize this state as being connected to a leaked or damaged lamp. In this case, the time constant circuit including the resistor 22 and the capacitor 21 has a function of canceling the output of the operational amplifier 18 for a certain period immediately after the power is turned on.

If any abnormality is detected, the switch circuit 1
When an "H" level abnormal signal is input to the switching element 5, the same potential is applied between the emitter and the base of the switching element 4, the switching element 4 is turned off, and the electric charge of the capacitor 9 is changed to the resistance 6, the resistance 8, and the switching element 7. And the switching element 10 is immediately turned off.

Also, even when the lamp 12 is in a normal state, when the battery is exhausted and the voltage of the power supply 11 is lower than the rated value, or when the voltage drops below the rated value, the switching element 4 is turned on through the Zener diode 23. Cannot be held in the switching element 10, so that the switching element 10
The state becomes f, and the power supply 11 and the inverter circuit 13 are disconnected.

In this manner, the switch circuit 15 can connect and disconnect the power supply 11 and the inverter circuit 13 while suppressing the rush current. The detection circuit 1
From FIG. 4, when an abnormality is detected in the lamp or when the power supply voltage drops, the ON state of the switch circuit is released, and the connection between the power supply 11 and the inverter circuit 13 is promptly interrupted, whereby the operation can be stopped.

[0047]

As described above, according to the present invention, the inrush current can be suppressed to prevent generation of large noise, and the operation of the lighting circuit can be stopped by detecting the state of the lamp and the abnormality of the power supply. It is possible to provide a safe discharge lamp lighting device with a simple configuration.

[Brief description of the drawings]

FIG. 1 shows a discharge lamp lighting device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a conventional lighting device.

[Explanation of symbols]

 1,3 push switch 4,7,10 switching element 6 resistor 9 capacitor 11 power supply 12 discharge lamp 13 inverter circuit 14 detection circuit 15 switch circuit 17,18 operational amplifier 19,20 reference voltage

Claims (1)

[Claims] A discharge circuit having a pair of electrodes therein; a switch circuit to be connected to a power supply; an inverter circuit; and a detection circuit for detecting a lamp state, wherein the switch circuit includes the power supply and the power supply. The connection between the power supply and the inverter circuit is determined by the On / Off state of the push switch or the state of the lamp detected by the detection circuit.
ff, comprising: a common switching element for switching the power supply, and a time constant circuit connected to the switching element for connecting the power supply and the inverter circuit with a predetermined time constant when power is turned on. apparatus.