JPS5942440B2 - discharge lamp lighting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a discharge lamp lighting device that cuts off the AC power applied to the discharge lamp after a predetermined period of time has elapsed since the power was turned on, when the discharge lamp malfunctions and stops lighting. .

In general, discharge lamps such as high-pressure sodium and metal halide lamps have a high starting voltage, so when starting up, the ballast has a high
A pulse voltage of several thousand volts is superimposed on the next voltage and applied,
It's starting to light up.

For example, as shown in FIG. 1, a conventional discharge lamp lighting device includes an AC power source IVC, a capacitor 2, and a reactor 3.
A discharge lamp 5 is connected through a ballast 4 consisting of a ballast 4, and this discharge lamp 5VC uses a bimetal as a lighting high voltage generating means for starting the discharge lamp 5, in addition to the main electrode 6 for emitting light. It has a built-in preheating heater 7 and contacts 8.
When the AC power source 1 is turned on, a preheating current flows through the ballast 4, the preheating heater 7, and the contacts 8, warming the discharge lamp 5 and opening the contacts 8. When this contact 8 is opened, a pulse voltage of several thousand volts is applied to the discharge lamp 5VC due to the charge in the capacitor 2 of the ballast 4, and the discharge lamp 5 is turned on. However, if the discharge lamp 5 deteriorates or becomes unable to light due to some other reason, the bimetal contact 8 will repeatedly open and short-circuit, and each time the contact 8 opens, a pulse of several thousand volts will be generated. often occurs.

Therefore, the normally used 600V discharge lamp 5
The electric wires and ballast 4 are severely deteriorated. In addition, replacing the discharge lamp 5 when high-voltage pulses are occurring involves extremely dangerous work, and furthermore, such a discharge lamp 5
are often installed on high ceilings in factories, gymnasiums, etc., and dangerous work is required to replace the discharge lamps 5 and rewire the electric wires. The present invention takes the above-mentioned points into consideration, and provides a system for discharging a discharge lamp that is equipped with a built-in or external high-voltage generating means necessary for lighting the discharge lamp, and when the discharge lamp fails and the discharge lamp no longer lights. The alternating current power applied to the discharge lamp is cut off after a predetermined period of time has elapsed since the power was turned on.Next, this invention will be explained in detail along with the drawings in Fig. 2 and Fig. 3 showing one embodiment of the invention. explain.

First, the basic configuration of the present invention will be explained with reference to FIG.

In the figure, the same symbols as in Figure 1 indicate the same things,
Reference numeral 9 denotes a timer, which is inserted between the AC power source 1 and the ballast 4 to detect that the AC power source 1 is applied to the ballast 4, and after a preset predetermined time has elapsed from the time of detection. The contact 9' is turned off to cut off the input to the ballast 4 of the AC power supply 1. A current detector 10 detects the current flowing through the discharge lamp 5, and detects the lighting current flowing through the main electrode 6VC and the preheating current flowing through the preheating heater 7 and contacts 8 to generate a high voltage.

11Y is a discriminator that discriminates only the lighting current from the current detected by the current detector 10, and applies the discriminated output signal to the timer 9 to reset the timer 9.

Next, in FIG. 3 showing details of the discriminator 11, R
C is a rectifier that rectifies the output of the current detector 10, C1 is a first smoothing capacitor connected between both output terminals of the rectifier RC, and Dl, Rh is a rectifier RC connected in series between both output terminals of the rectifier RC. The first diode D1 and the first resistor R2 for preventing reverse current, through which the output current 11 flows, are connected to the DC power supply +V.
cc and the connection point of the first diode D1} and the first resistor R1, and when the preheating current is flowing, the current is larger than the current flowing through the first diode D1, and the light is turned on. When current is flowing, the first D4 auto DlVC. A current 12 smaller than the flowing current is caused to flow.

Q1 is a first transistor connected to one end of a second resistor R2 via a base resistor R3, and whose emitter is connected to a DC power supply +CcVc and a positive output terminal of a rectifier RC via a fourth collector resistor R4. , is turned on by a current 13 obtained by subtracting the current 11 from the current 12. C2 is the first
A second smoothing capacitor is connected between the base and emitter of transistor Q1, and Q2 is connected to the first transistor Q.
This is a second transistor that inverts the output of the first transistor Q1 and resets the timer 9. Its base is connected to the collector of the first transistor Q1, the collector is connected to the DC power supply +Vcc via the fifth resistor R5, and its emitter is connected to the rectifier RC. Each is connected to the positive output terminal. D2 and R2 are a second diode for preventing reverse current and a sixth resistor for current limiting, which are connected in series to the collector of the second transistor Q2. In addition, in the block indicating the timer 9, R7 and C3 are a seventh resistor and a third capacitor that constitute a time constant circuit, which detect the AC power supply 1 applied to the ballast 4 and convert it into a rectifier circuit. Connection between the seventh resistor R7 and the third capacitor C3 is connected in series between the rectified and smoothed DC power supply +Vcc from a power supply (not shown) and a smoothing circuit (not shown) and the positive input terminal of the rectifier RC. The point is connected to one end of the sixth resistor R6. S is a switching circuit connected to the connection point, and is a semiconductor switching element that turns on when the third capacitor C3 is charged to a predetermined voltage value, and is energized by turning on the semiconductor switching element to open the contact 9'. Consists of relays, etc. Next, the operation of the above embodiment will be explained. When the AC power supply 1 is applied to a normal discharge lamp 5, a preheating current flows through the ballast 4, the preheating heater 7, and the contacts 8.
After the required time has elapsed, the contacts 8 are opened, a pulse voltage of several thousand volts is generated, and the discharge lamp 5 is lit. Here, the time constant of the timer 9 is preset to the time required for relighting the discharge lamp 5 according to the characteristics of the discharge lamp 5. Diode D1
The current 1 flowing through the second resistor R2rfc becomes larger than the current 12 flowing through the second resistor R2rfc, the base current 13 of the first transistor Q1 becomes zero, the first transistor Q1 shifts from the on state during preheating to the off state, and the second transistor Q2 of
is turned on, the charge in the third capacitor C3 is discharged through the second transistor Q2, and the timer 9 is reset, so that the voltage across the third capacitor C3 does not reach the operating voltage of the switching circuit S. , the contact 9' remains on, and the discharge lamp 5 continues to light normally. Next, when a short power outage occurs in the AC power supply 1, the discharge lamp 5 is turned off and the DC power supply -1Vcc becomes zero, so that the third capacitor C3 of the timer 9 is not charged. When the AC power supply 1 recovers from the power outage, the timer 9 detects the AC input to the ballast 4, and from the time of detection, the third capacitor C3 starts to be charged by the DC power supply +Vcc. Since the contact point 8 has returned to its original state after being cooled, a preheating current flows, the contact point 8 opens, a pulse voltage is generated, and the discharge lamp 5 is lit again. Since the time constant of the timer 9 is set to the predetermined time from when the AC power supply 1 recovers from a power outage until the discharge lamp 5 is lit again, as described above, the short-term power outage of the AC power supply 1 Normal operation can be performed even in this case. When the discharge lamp 5 deteriorates or becomes unable to light up for some reason, the discharge lamp 5 is turned off and cooled, the contact 8 is restored and a preheating current flows, and further, Although the contact 8 is opened and a pulse voltage is generated, the discharge lamp 5 does not light up, but the contact 8 returns and the preheating current flows, and the operation is repeated. Therefore, the current 11 detected by the current detector 10 and flowing to the first diode D1 via the rectifier RC is transferred to the second resistor R.
The current 12 flowing through the second resistor R2 is shunted to the base of the first transistor Q1, turning on the first transistor Q1 and turning off the second transistor Q2. Therefore, the third capacitor C3 of the timer 9 is charged, and when the voltage across the third capacitor C3 exceeds the set value of the operating voltage of the switching circuit S, the switching circuit S operates and the contact 9 is opened. state, and the AC input applied to the discharge lamp 5 is cut off. In the above embodiment, a case has been described in which a discharge lamp 5 having a built-in high voltage generating means such as a bimetal contact 8 is lit. Of course, it can also be applied.

As described above, according to the discharge lamp lighting device of the present invention, the discharge lamp has a high voltage generating means for lighting and is connected to an AC power source via a ballast, and the application of the AC power to the ballast is detected. Additionally, a timer device that cuts off the input of the AC power source to the ballast after a predetermined period of time has elapsed from the time of detection, and a current detector that detects the preheating current flowing through the high voltage generating means and the lighting current when lighting the discharge lamp. and a discriminator for discriminating the lighting current from the current detected by the current detector and resetting the timer. By cutting off the input to the discharge lamp, it is possible to reliably cut off the AC input applied to the discharge lamp only when the discharge lamp malfunctions, and there is no need to replace the discharge lamp every time the discharge lamp malfunctions. In addition, the electric wires for wiring the discharge lamp and the ballast do not deteriorate, making it easier to replace the discharge lamp.

[Brief explanation of the drawing]

Fig. 1 is a wiring diagram of a conventional discharge lamp lighting device, Fig. 2 is a wiring diagram of an embodiment of the discharge lamp lighting device of the present invention, and Fig. 3 is a detailed wiring diagram of the discriminator shown in Fig. 2. . 1... AC power supply, 4... Ballast, 5.
...Discharge lamp, 7... Preheating heater, 8.
...Contact, 9...Timer, 10...
...Current detector, 11...Discriminator.

Claims (1)

[Claims] 1. A discharge lamp that has a high voltage generating means for lighting and is connected to an AC power source via a ballast, and detects the application of the AC power to the ballast and turns off the AC power source after a predetermined period of time set from the time of detection. a current detector that detects a preheating current flowing through the high voltage generating means and a lighting current when lighting the discharge lamp; and a current detector that detects a current detected by the current detector. a discriminator that discriminates the lighting current and resets the timer, and when the discharge lamp does not light up by the predetermined time after the AC power is applied, the AC power is applied to the ballast. A discharge lamp lighting device characterized by cutting off input.