JPH02242586A - Lamp driving circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a lamp drive circuit that drives an aircraft guide light at an airport with a constant current, and includes a detection means for detecting lighting of the lamp and turning off due to core breakage; and a semiconductor switch circuit that is connected in parallel to the lamp, and the semiconductor switch circuit is turned off when the signal supplied from the detection means corresponds to lamp lighting and turned on when the signal corresponds to lamp dimming due to core breakage. With this configuration, it is possible to provide a highly reliable lamp drive circuit that can reliably short-circuit the output terminals of the current transformer when the lamp is broken.

<Prior Art> Conventionally, a lamp drive circuit for lighting guide lights or runway lights at an airport has a configuration shown in FIG. In FIG. 3, 1 is a constant current source, 2 is n current transformers, 3 is n lamps, and 4 is n switches.

The current transformers 2 are provided in the same number as the lamps 3, and are individually connected to the lamps 3.

A switch 4 is connected in parallel to each of the lamps 3. These switches 4 remain open while a voltage within a predetermined range is applied between the electrodes, or when an overvoltage is applied between the electrodes, the insulation between the electrodes melts and the electrodes are closed. It has a structure made of The device for fusing the insulation between the electrodes is called a film cut-out.

In the lamp drive circuit shown in Fig. 3, in a normal state in which the lamp 3 is not broken, energy is supplied from the constant current source 1'/J) to the lamp 3 through the current transformer 2, and the lamp 3 is lit. . At this time, switch 4 is off.

If any of the lamps 3 is broken, since it is driven by the constant current source 1, among the current transformers 2,
Current transformer 2 to which the broken lamp 3 is connected
Overvoltage occurs on the output side. Therefore, current transformer 2
The insulator between the electrodes of the switch 4 connected to the current transformer 2 is fused and closed between the electrodes, thereby protecting the current transformer 2.

<Problem to be solved by the invention> However, the conventional lamp lighting drive circuit has a current of 1.
The switch 4 connected to the output terminal of the lance 2 has a mechanical contact structure that, when an overvoltage is applied between the electrodes, the insulation between the electrodes melts and the electrodes are closed. In addition to lower reliability, the overvoltage detection level of the insulator between the electrodes of the switch was high, and there were cases where the electrodes were not short-circuited.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and provide a highly reliable lamp drive circuit that can reliably short-circuit the output terminals of a current transformer when the lamp is broken.

<Means for Solving the Problems> In order to solve the problems reached, the present invention provides a semiconductor switch circuit connected between a current transformer driven by a constant current source and an output terminal of the current transformer. a lamp drive circuit that includes a lamp that is connected in parallel with the semiconductor switch circuit; and a detection means that detects whether the lamp is turned on or off due to core breakage and supplies a signal thereof to the semiconductor switch circuit; The switch circuit is characterized in that it is turned off when the signal supplied from the detection means corresponds to lighting of the lamp, and turned on when the signal supplied from the detection means corresponds to turning off of the lamp due to core breakage.

<Operation> Under normal conditions, when the lamp is not broken and the lamp is lit by receiving energy supplied from the constant current source through the current transformer, the detection means detects lamp lighting, and the semiconductor The switch circuit is turned off based on the signal supplied from the detection means.

If a core break occurs in the lamp, the lamp will go out.

Lamp dimming is detected by the detection means. The semiconductor switch is controlled to be turned on by a signal supplied from the detection means at this time. When the semiconductor switch circuit is turned on, the output terminals of the current transformer are short-circuited. This protects the current transformer.

As described above, according to the present invention, the lighting of the lamp and the turning off of the lamp due to core breakage are detected, and the output terminals of the current transformer are short-circuited without contact by the semiconductor switch circuit, and the current transformer is driven by a constant current source. It is possible to reliably protect against overvoltage during operation.

<Embodiment> FIG. 1 shows a block diagram of a specific embodiment of a protection switch circuit according to the present invention. In the embodiment, in order to simplify the explanation, only one circuit configuration required to drive one lamp is shown, but in reality, as shown in FIG. and a driving circuit thereof.

In the figure, 2 is a current transformer, 3 is a lamp, 5 is a semiconductor switch circuit, 6 is a transformer that extracts the current flowing through the lamp 3, 7 is a rectifier circuit, 8 is a current limiting resistor, T1, T2
is the output terminal of the current transformer 2, T3 and T4 are the rectifier circuit 7
The input terminals T5 and T6 of the semiconductor switch circuit 5 for receiving the output signal of are terminals connected to a constant current source (see FIG. 1).

The semiconductor switch circuit 5 keeps the output terminals T and -T2 open when an input signal is applied to the input terminals T3 and T4, and opens the output terminal T when no human input signal is applied to the input terminals T3 and T4. , -T2 is maintained in a closed state.

The transformer 6, the rectifier circuit 7, and the current limiting resistor 8 constitute a current detection circuit, and determine whether the lamp 30 is turned on or turned off due to core breakage.
Detection is done based on the presence or absence of lamp current.

As another example of detecting whether the lamp 30 is on or off due to core breakage, it is also effective to monitor the light of the lamp 3 with an optical sensor and to replace the N source of this sensor with a separate external power source.

Next, the operation of the embodiment shown in FIG. 1 will be explained.

It is assumed that an alternating current is applied between terminals T5 and T6 from a constant current source (see FIG. 3). This current generates an output voltage between the current l and the output 1 of the lance 2, T and -72, the lamp 3 lights up, and the lighting current generates an alternating current output voltage at the -lance 6. This AC output voltage is converted into a DC voltage by a rectifier circuit 7, and a current limiting resistor 8
Through the semiconductor switch circuit 50 input terminals. -14
Human power is applied in between. At this time, the output terminals T and -72 of the semiconductor switch circuit 5 are in an open state.

If the lamp 3 is broken, an output voltage will be generated in the transformer 6, and the input terminal 'j' of the semiconductor switch circuit 5 will be
No DC voltage is input between Ts and T4. Therefore, the output terminal T + '- of the semiconductor switch circuit 5
T2 is closed, and thereafter, the semiconductor switching circuit 5 continues to maintain the output terminal TI72 in a closed state while no voltage is input between the input terminals T3 and T4. This state remains unchanged until the lamp 3 is replaced, the core breakage is resolved, and the lamp current flows.

Next, FIG. 2 shows an example of a specific configuration of the semiconductor switchover circuit 5 having the characteristics described above. In FIG. 2, output terminals T + and T 2 and input terminals T3 and T4 correspond to output terminals T1 and T2 and input terminals T3 and T4 in FIG. 1. 9 is a bidirectional thyristor such as a tria, 10 to 15 are resistors, 17 to 20 are diodes, 21
2 is a thyristor, 22 is a transistor, 23 is a capacitor, and 24.25 is a light-emitting element and a light-receiving element constituting the points 1 to 25 PC.

In FIG. 2, if the lamp 3 in FIG. 1 is normal and no DC voltage is applied to the terminals T3 and T4 via the transformer 6, rectifier circuit 7 and current limiting resistor 8, the photocoupler PC
The light-receiving element 25 is turned on, a base current flows to the transistor 22 via the resistor 10.11, and the transistor 22 is turned on. Therefore, the AC voltage between the output terminals 'fTt-T2 or the diode 18.19 or the diode 17.2
Even if the voltage is applied to the thyristor 21 through 0, the thyristor 21 does not turn on.

If lamp 3 in Fig. 1 is broken, input terminals T3 and T4
If no input voltage is applied to the photocoupler PC, the light receiving element 25 of the photocoupler PC will not turn on, so the transistor 22 will be in the off state, and the gate current will be supplied to the thyristor 2 through the resistor 13. Therefore, when a positive voltage is applied to the output terminal T2 and a negative voltage is applied to the output terminal T1, a current is simultaneously supplied to the gate of the bidirectional thyristor 9 via the tie auto 18, the thyristor 21, and the diode 19. Bidirectional thyristor 9 is turned on. Furthermore, when a positive voltage is applied to the output terminal T and a negative voltage is applied to the output terminal T2, a current C flows through the resistor 15, the tie-out 17, the thyristor 21, and the diode 20, and the current flows through the terminal of the resistor 15. The voltage turns on the bidirectional thyristor 9. That is, input terminal T3
, T4, the bidirectional thyristor 9 remains on.

The purpose of the capacitor 23 is to delay the turn-on time of the bidirectional thyristor 9 by delaying the rise of the full-wave rectified voltage applied to the thyristor 21, and at this time, the current flowing through the lamp 3 causes an output voltage to be generated in the rectifier circuit 6. have. That is, considering the case where there is no capacitor 23,
When a voltage is applied to the terminals T5 and T6 (see Figure 1) at the time of rising, the output terminals T1 and T of the current transformer 2
2 is kept open by a semiconductor switch circuit 5, so that no current is supplied to the lamp 3. If a capacitor 23 is provided for the kneading, when a voltage is applied to the terminals T5 and T6 and the terminal voltage of the thyristor 21 rises, the base current flows to the transistor 22 via the resistor 17 and the capacitor 20. flows, and while this current flows, 1
- transistor 22 is in the on state and thyristor 21
is not turned on.

Therefore, at startup, the thyristor 21 can be kept off and the lamp 3 can be turned on.

The resistor 12 is a resistor that allows the leakage current of the transistor 22 to flow, and the resistor 14 is a dummy load resistor of a rectifier circuit constituted by ties 17 to 20.

<Effects of the Invention> As described above, according to the present invention, lighting of the lamp and turning off due to core breakage are monitored, and when the lamp core is broken, the connection between the output terminals of the current transformer is connected by a mechanical contact. First, it is possible to provide a highly reliable lamp drive circuit that can be reliably short-circuited using a semiconductor switch circuit.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the lamp drive circuit according to the present invention, FIG. 2 is a block diagram showing an embodiment of the semiconductor switch circuit in the embodiment of FIG. 1, and FIG. 3 is a block diagram of a conventional lamp drive circuit. A configuration diagram is shown. 2...Current transformer 3...Lamp 5...Semiconductor switch circuit

Claims (1)

[Claims] A current transformer driven by a constant current source, a semiconductor switch circuit connected between output side terminals of the current transformer,
A lamp drive circuit including a lamp connected in parallel with the semiconductor switch circuit, and a detection means for detecting lighting of the lamp and turning off due to core breakage and supplying a signal thereof to the semiconductor switch circuit, the semiconductor switch circuit The lamp drive circuit is characterized in that it is turned off when the signal supplied from the detection means corresponds to lamp lighting, and turned on when the signal supplied from the detection means corresponds to lamp extinguishment due to core breakage.