JPH0632313B2 - Discharge lamp lighting device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a discharge lamp lighting device for lighting a discharge lamp such as a fluorescent lamp at a high frequency, and more particularly to a protection device for abnormal times.

BACKGROUND ART Conventionally, as a discharge lamp lighting device of this type, a DC power supply (including a power supply obtained by rectifying an AC power supply), a high frequency generator that generates a high frequency output by its output, and a high frequency output of this high frequency generator are used. Devices are known which comprise a preheat and a discharge lamp (or lamp) which is turned on. By the way, in such a device, in the case of rectification lighting that occurs at no load and at the end of the life of the discharge lamp, a high voltage is applied between terminals connected to both ends of the discharge lamp, and excessive stress is applied to the high frequency generator. There is an inconvenience of this.

Therefore, FIG. 11 shows a conventional example (Japanese Patent Laid-Open No. 58-189991) that solves the above problem.

The circuit configuration is a constant current type push-pull inverter type high frequency generator 54, a detection circuit 72 including a detection winding 60g of an oscillation transformer 60 of the high frequency generator 54, a control circuit 52 which operates by the detection output, and a preheater. It comprises a timer circuit 63.

The operation will be described based on the above configuration. After the power is turned on, the transistor 64 is turned off for a certain period of time by the preheat timer circuit 63, the output of the high frequency generator 54 is lowered, and the discharge lamp 62 is preheated. Next, after a certain period of time, the transistor 64 is turned on, a voltage is applied to the high-frequency generator 54 from the DC power supply 51, and a voltage is also applied to the discharge lamp 62 so that the discharge lamp 62 is turned on. When the discharge lamp 62 is normally turned on, the detected voltage obtained from the detection winding 60g is the Zener diode 75.
However, for example, when a half-wave discharge occurs at the end of the lamp life, a high voltage equal to or higher than the Zener voltage is generated, and as a result, the transistor 53 is turned on and the transistor 64 is turned off to reduce the output. There is. Then, the detection voltage becomes low and becomes a preheating state, and after the timer time, the modes of lighting->detection-> squeezing the output-> preheating are repeated, and the discharge lamp 62 becomes a faulty state.

However, the above circuit also has the following problems. That is, even after the intermittent operation, the high-frequency generator 54 is operating even if the engine cannot be started, and the state of electrical loss continues, which is not preferable in terms of reliability.

[Object of the Invention] The present invention has been provided in view of the above points, and when the discharge lamp is abnormally lit, intermittent operation is performed to notify the abnormality, and thereafter, the output of the inverter circuit A discharge lamp lighting device intended to maintain a stop.

DISCLOSURE OF THE INVENTION Embodiment 1 An embodiment of the present invention will be described below with reference to the drawings. Fig. 1
(a) shows a block diagram of the present invention, and (b) shows a flow chart. In FIGS. 1 (a) and 1 (b), a discharge lamp 1 is an inverter circuit 3 using a DC power source E ₁ as a power source.
When the discharge lamp 1 becomes a half-wave discharge at the end of its life, the abnormality detection circuit 7 detects the abnormality and receives an abnormality detection signal from the abnormality detection circuit 7. The first output control means 15 controls the inverter circuit 3 to stop the output of the discharge lamp l, and by stopping the output of the discharge lamp l, the abnormality detection circuit 7 cancels the abnormality detection. l is normally turned on. Then, when the lighting operation is performed, the abnormality detection is performed again, and this operation of stopping the output of the discharge lamp l is repeated. By repeating this, for example, the discharge lamp 1 is in a blinking state, and a function of notifying the lamp life is provided. Further, the timer circuit 9 repeats the above operation for a certain period of time, and thereafter the second output control means 1
6, the output of the discharge lamp 1 is stopped and the state is maintained.

FIG. 2 (a) shows the lamp voltage waveform of the discharge lamp 1 during the above operation, T in the figure shows the initial preheating time, a is the abnormal lighting time, and b is the oscillation stop time. Ta represents the preheating time after the oscillation is stopped. Further, FIG. 2B shows the operation of the timer circuit 9.

(Embodiment 2) FIG. 3 shows another embodiment. The structure is as follows. Two transistors Q ₁ and Q ₂ and emitter resistors R ₁ and R ₂ are connected in series to the DC power source E ₁ as shown in the drawing, and the transistor Q ₁ and the resistor R ₁ , the transistor Q ₂ and the resistor R ₂ are connected to _each other. and connected in antiparallel to each of the diodes _D 1, _{D 2,} also in parallel with its diode _{D 1,} the capacitor _{C 1,} the discharge lamp _l 1, _{l 2,} the inductance _{L 1,} 1 winding of the drive transformer _{T 1} A series circuit with n ₁ is connected. Further, a capacitor C ₂ is connected to both ends of the discharge lamps l ₁ and l ₂ connected in series, which constitutes a modification of the half bridge inverter circuit. The starting circuit 2 charges the capacitor C ₃ via the resistor R ₅ ,
When the voltage exceeds the breakover voltage of the bidirectional device, for example, Diac Q _3, a pulsed ON signal is applied to the base of the transistor Q ₂ . Further, when the oscillation is started, the starting pulse is stopped by the diode D ₈ . The oscillation is started by the above start pulse, and the secondary winding of the drive transformer T ₁ is
The switching transistors Q ₁ and Q ₂ are controlled by n ₂ and n ₃ .
When the base current is applied to the base through the resistors R ₃ and R ₄ , oscillation is maintained. Also, the discharge lamps l ₁ , l
_{Since 2} are connected in series and a high voltage is required at the time of starting, a resonant circuit is configured by the inductance L ₁ and the capacitor C ₂ to obtain a high voltage. Further, the capacitor C ₁ also has a role of cutting a direct current.

Next, regarding the configuration of the control unit, the DC power supply E ₂ is ideally a DC voltage with as little ripple as possible, and the purpose is to be a power supply for operating the entire control unit.
V is appropriate. For example, the description will be given below assuming that the voltage is 15V. The preheat timer circuit 12 has a resistor R ₂₉ and a capacitor C.
_{It comprises 14} charging circuits, a comparator CP _{4 and the} like to which a reference voltage resulting from the voltage division of the resistors R ₃₀ and R ₃₁ is input. The preheat timer time is determined by the charging time of the resistor R ₂₉ and the capacitor C ₁₄ , and it is considered that about 1 second is suitable. The preheat timer circuit 12 also serves as the preheat switch control circuit 8. A resistor R ₂₈ and a transistor Q ₁₂ are connected in series to both ends of the capacitor C ₁₄ , and a series circuit of a resistor R ₄₇ and a transistor Q ₁₆ is connected to both ends of the DC power source E ₂ . And a resistor R ₄₇ and a transistor Q ₁₆
The middle point is connected to the base of the transistor Q ₁₂ via the base resistor R ₂₇ . Further, the base of the transistor Q ₁₆ is connected from the point Y of the abnormality detecting circuit 7 through the resistor R ₄₈ . Further, the circuit for turning on / off the preheat switch 6 is a relay R by turning on / off the transistor Q _11.
This is done by passing or not passing a current through the exciting coil of y ₁ . In this circuit, the contact of the relay Ry ₁ which is the preheat switch 6 is normally open and used (the preheat switch 6 is opened by turning on the transistor Q ₁₁ ).

Next, the abnormality detection circuit 7 described above is an example of a circuit that detects an abnormality of the lamp by the voltage. From the connection point X of the capacitors C ₁ and C ₂ in the inverter circuit 3 via the diode D ₁₂ and the resistors R ₄₅ and R ₄₆ , the DC power sources E ₁ and E ₂ are
One end of the resistor R ₄₆ is connected to the + side input of the comparator CP ₇ , and the other is connected to the − side of the DC power source E ₂ via the transistor Q ₁₅ to connect the side of the comparator CP ₇ to the side. Output is transistor Q via resistor R ₄₄
It is connected to ₁₅ bases. The output of the abnormality detection circuit 7 is
The abnormal state of the discharge lamp l is detected. Here, the abnormal state means the end of life of the discharge lamp l and the case of no load. Half-wave lighting at no load and at the end of life of the discharge lamp l. 3 is an example of a circuit in which the potential at the point Y of the abnormality detection circuit 7 in FIG. 3 becomes "0V".

The oscillation stopping circuit 11 has a diode D ₉ and a transistor Q ₉ connected to both ends of a tertiary winding n ₄ of a drive transformer T ₁ , and a resistor R ₂₄ and a transistor Q ₁₀ connected in series to both ends of a DC power source E _2. The collector of the transistor Q ₁₀ is connected to the base of the transistor Q ₉ through the diode D ₁₀ and the resistor R ₂₃ , and the output of the timer circuit 9 is connected to the diode D 10.
It is connected to one end of a resistor R ₂₃ through ₁₁ . The timer circuit 9 inverts the output of the comparator CP ₄ which is the output of the preheat switch control circuit 8 by the inverter gate I ₃ ,
The capacitor C ₁₅ of the charging circuit composed of the resistor R ₃₅ and the capacitor C ₁₅ is charged from the output, and the midpoint thereof is connected to the-input terminal of the comparator CP ₅ . Also,
The + input terminal of the comparator CP ₅ has a DC power source E ₂
Is applied with a voltage divided by resistors R ₃₀ and R ₃₁ , and its output is input to the transistor Q ₁₃ . The operation is such that when the output of the inverter gate I ₃ is “1”, the capacitor C ₁₅ is charged through the resistor R _35, and when the charging voltage of this capacitor C ₁₅ exceeds the voltage of the + input terminal of the comparator CP ₅ , The output signal of the comparator CP ₅ changes from “1” to “0”. Here, the comparator CP ₅
The condition that the output speech signal of "1" changes from "1" to "0" is always longer than the preheating timer time. Further, a charging circuit composed of a transistor Q ₁₄ , a resistor R ₃₉ and a capacitor C ₁₆ which operates upon receiving the above signal, and a discharging resistor ₄₁ connected in parallel with the capacitor C ₁₆ .
A resistor R ₃₈ connected to the base of the transistor QR _14.
And the transistor Q ₁₃ is formed. The DC power supply E ₂ is divided by resistors R ₄₀ and R ₄₃ , the divided voltage is connected to the + input terminal of the comparator CP ₆ , and the − input terminal is connected to one end of the capacitor C ₁₆ . .

FIG. 4 shows the state of the voltage at point Y of the abnormality detection circuit 7, which is 0 V when there is no load, AV during preheating and lighting, and 0 V depending on the half-wave lighting direction at the end of the lamp life.
Alternatively, it becomes BV.

In the case of lighting at the end of the life, 0V or BV is assumed to be a series connection of a resistor and a diode virtually at the time of lighting at the end of the life, so that potentials of 0V and BV appear depending on the direction of the diode. Is. The reason for this will be described below. By the way, the discharge lamp l which is lit by the high frequency output as described above is not a problem when it is normally lit, but when the discharge lamp l reaches the end of its life, the filaments at both ends of the discharge lamp l are unbalanced. Therefore, it becomes a direct current lighting of unbalanced positive and negative,
Alternatively, the discharge sustaining voltage rises and the lighting becomes unstable, causing abnormal oscillation (lighting at the end of life). That is, when the discharge lamp 1 is viewed, filaments coated with an active substance are provided at both ends thereof, and the discharge lamp 1 is turned on by alternately discharging the filaments. In that case, the active substance on one filament is completely peeled off, resulting in "DC lighting" due to discharge in only one direction, or when a small amount of the active substance on one filament remains Depending on the balance, abnormal lighting may be slightly different from DC lighting. in this way,
When the filament of the discharge lamp 1 becomes unbalanced, a large current of 3 to 4 times the normal current flows through the transistors Q ₁ and Q ₂ .

Next, the above reason will be specifically described. In this embodiment, two discharge lamps l ₁ and l ₂ are used, but first, the case where there is one discharge lamp 1 will be described.

<Operation during normal lighting> In the case of normal lighting, the equivalent basic circuit is expressed as shown in FIG. In this case, the voltage e _1, e ₂ appearing across transistors Q _1, Q ₂ by the switching operation of the transistor Q _1, Q ₂ are each FIG. 7 (b), becomes a square wave voltage, such as shown in (c), The discharge lamp 1 is supplied with a voltage er as shown in FIG. 7 (e), the direct current component of which is cut by the capacitor C ₁ . Incidentally, FIG. 7 (a) shows a DC power source E ₁
The voltage E is shown. Here, the voltage e across the capacitor C ₁
c _1, since obtained by ec _{1 =} e ₁ -er, the voltage across ec ₁ of the capacitor _{C 1} becomes E / D. Although a slight ripple is included in FIG. 7, this ripple is reduced by increasing the value of the time constant C ₁ · R of the impedance R of the capacitor C ₁ and the discharge lamp l. Further, the voltage e ₃ across the resonance circuit composed of the discharge lamp l, the inductance L ₁ , the capacitor C _2, etc. is e ₃ = e ₁
-Ec ₁ further causes the voltage e applied to the abnormality detection circuit 7
₄ are respectively obtained by e ₄ = e ₂ + e ₃ ,
The waveforms shown in FIGS. 7 (f) and 7 (g) are obtained, and e ₄ = E / 2 is obtained. Therefore, in the case of normal lighting, the voltage e ₄ generated in the abnormality detection circuit 7 becomes E / D (AV described above).

<Operation at end of life of discharge lamp> As described above, when the discharge lamp reaches the end of its life (Emiles), the active substance on one filament is completely peeled off, resulting in "DC lighting" due to discharge in only one direction. The equivalent basic circuit is shown in FIGS. 8 (a) and 8 (b) depending on the polarity.
Here, Kodensa _C 1, _{C 2} since satisfies the relationship of _C 1 »C _2, the capacitor _{C 2} does not affect the most operation. As described above, the discharge lamp 1 has a virtual resistance r.
And the diode d.

(A) In the case of the operation of FIG. 8 (a) When the transistor Q ₂ is turned on, a loop current flows, and the capacitor C ₁ flows in the direction shown by the DC power supply E ₁ all at once.
It is charged up to the voltage E. Next, when the transistor Q ₁ is turned on, the discharge current of the capacitor C ₁ slightly flows through the capacitor C _{2 as} shown by the broken line, but C ₁ >> C ₂
Therefore, the potential of the capacitor C ₁ remains E. Since the voltage e ₄ across the abnormality detection circuit 7 is found by e ₄ = e ₀ −ec ₁ , the voltage of e ₄ is 0 level.

(B) Operation of FIG. 8 (b) In the case of FIG. 8 (b), when the power switch is closed, the capacitor C ₁ loops in the direction shown in the figure through the impedance Ro of the abnormality detection circuit 7. It is charged (voltage ec ₁ ). Although the capacitor C ₁ is charged with a time constant determined by C ₁ · Ro, the impedance Ro of the abnormality detection circuit 7 is selected to be a very high impedance value as compared with the discharge lamp load, so that the inverter immediately When the circuit 30 starts oscillating and the transistor Q ₁ turns on, a current flows in the loop, and the capacitor C ₁ is charged in the direction opposite to that shown in the figure. At this time, since the impedance r of the discharge lamp 1 is an abnormally low impedance, the capacitor C ₁ is charged all the way to E in the opposite direction to the direction shown in the figure. Next, when the transistor Q ₂ is turned on, a current tends to flow in the loop, but since the discharge lamp 1 is performing direct current lighting with the polarity shown, this loop does not actually exist. Further, the transistor Q ₂ is turned off, the transistor Q ₁ is the capacitor C ₁ between the time to turn on is slightly charged by the loop, immediately transistor Q ₁
Is turned on, the capacitor C ₁ is charged to E in the direction opposite to that shown by the large current due to the loop. As described above, in the case of FIG. 8 (b), the capacitor C ₁ is charged up to E in the direction opposite to that shown, and the voltage e ₄ generated at both ends of the abnormality detection circuit 7 becomes the voltage E of e ₀ ec ₁ Is applied, so that e ₄ = 2E (BV described above).

(C) In the case of multi-lamp lighting In the case of multi-lamp lighting, for example, two discharge lamps l ₁ and l ₂ are at the end of their life at the same time, and DC lighting may occur, as shown in FIG. 9. At this time, when the polarities of the _two discharge lamps l ₁ and l ₂ are as shown in FIG. 9 (a) or (b), no current flows through the discharge lamp l, so that the discharge lamp l does not light up and both ends of the capacitor C ₂ are not lit. As for the voltage, the same voltage as that of no load is generated, and a large current also flows through the transistors Q ₁ and Q ₂ , leading to destruction. In this case, in the configuration of the present embodiment, the impedance of the capacitor C ₂ is much larger than the impedance of the capacitor C ₁ , so the output terminal can be regarded as open, and the equivalent basic circuit is further written as shown in FIG. expressed. At this time, the current flows in the loop of, and the capacitor C ₁ moves in the direction of E in the drawing.
Thus, the voltage e ₄ across the abnormality detection circuit 7 becomes 0 level. Therefore, as will be described later, the inverter circuit 3 stops the oscillation operation as in the case of FIG.

Next, the operation of the circuit shown in FIG. 3 will be described. First, when the discharge lamp 1 is in the half-wave discharge state at the end of its life, the voltage at the point Y of the abnormality detection circuit 7 may be 0V or high. When the voltage at the point Y of the abnormality detection circuit 7 is 0V, the transistor Q ₁₆ is turned off, the transistor Q ₁₂ is turned on, and the capacitor C is turned on.
The charge of ₁₄ is rapidly discharged, the output of the comparator CP ₄ is set to L level, the preheat switch 6 is closed, and Y
The potential of 0V turns off the transistor Q ₁₀ and turns on the transistor Q ₉ to stop the oscillation of the inverter circuit 3. However, although it is re-started by the start-up pulse of the start-up circuit 2 and oscillation is started, the passing lighting operation is performed after the preheating for a certain time.

Here, the reason for restarting will be described. That is, when the oscillation is stopped as described above, the potential at the point Y via the point X becomes equal to the resistance R ₅ and the diode with respect to the DC power source E ₁ when the discharge lamps l ₁ and l _2, that is, the filament is inserted. D ₈ , primary winding of drive transistor T ₁ , inductance L ₁ , filament, preheat switch 6, diode D
_12, since the loop is a resistor R _45, R _46, becomes divided potential of the resistors R _45, R _46, its potential is 2-3 V. Therefore, with this potential, the transistor Q ₁₆ and the transistor Q ₁₀ are turned on, the oscillation stop circuit 11 is released, the preheat timer 12 is operated, and the preheat switch 6 is opened after a predetermined time of preheating has elapsed.

However, the discharge lamp 1 is again in a half-wave discharge state, and the above operation is repeated. Repeat this process for preheat switch control circuit 8
The output of the comparator CP ₄ of the resistor R ₃₅ and the capacitor C
When it is charged with a time constant of ₁₅ and exceeds a certain potential, the output of the comparator CP ₅ is inverted, the transistors Q ₁₃ and Q ₁₄ are turned off, and the electric charge of the capacitor C ₁₆ is discharged through the resistor R ₄₁ . The output of the comparator CP ₆ is inverted after a certain period of time to turn on the transistor Q ₉ of the oscillation stop circuit 11 to stop the oscillation. This state is shown in FIG. FIG. 5 (a) shows the output of the inverter gate I ₃ , and FIG. 5 (b) shows the potential of the capacitor C ₁₅ .
(c) shows the output of the comparator CP ₅ , respectively. As described above, the reason why the timer at the end of the lamp life is composed of two stages is to prevent the oscillation from being stopped when the detection is activated due to some abnormality (for example, starting at an abnormally low temperature).

When the voltage at the Y point is high, the output of the comparator CP ₇ becomes H level, the transistor Q ₁₅ is turned on, and the voltage at the Y point is set to 0V. That is, when the voltage at the point Y is the voltage at the time of preheating or lighting (AV shown in FIG. 4), the zener voltage of the zener diode ZD ₁ is higher, and the output of the comparator CP ₇ is at the L level. Therefore transistor _{Q 15} is not turned on. However, when the voltage at the Y point is high (BV shown in FIG. 4), the zener diode Z
Since the voltage at the Y point is larger than the Zener voltage of D ₁ , the output of the comparator CP ₇ becomes “H” level, the transistor Q ₁₅ is turned on, and the voltage at the Y point becomes 0V.

Therefore, the transistor ₁₆ is turned off, the transistor Q ₁₂ is turned on, the charge of the capacitor C ₁₄ is rapidly discharged, the output of the comparator CP ₄ is set to L level, and the preheat switch 6 is turned on.
And the transistor Q ₁₀ is turned off by the potential of 0 V at the point Y to turn on the transistor Q ₉ and stop the oscillation of the inverter circuit 3. Then comparator C
The output of P ₇ becomes “L” level, the transistor Q ₁₅ is turned off, and the initial state is set. Next, when the oscillation is stopped, in the case of half-wave lighting of the discharge lamp l at the end of its life, the filaments f ₁ and f ₂ are inserted, so that a voltage of 2 or 3 V appears at the point Y,
The transistors Q ₁₆ and Q ₁₀ are turned on, the oscillation stop circuit 11 is released, the preheat timer circuit 12 operates, the preheat switch 6 is closed, and the preheat switch 6 is opened after a predetermined time of preheating. Then, similarly to the above, the discharge lamp 1 is in a half-wave lighting state, and a high voltage is generated at the point Y. The discharge lamp 1 blinks as the voltage at the point Y is repeatedly increased and decreased. Therefore, in the case of the end of the life of the discharge lamp 1, the discharge lamp 1 is at the end of its life due to the intermittent operation (flashing) of half-wave lighting and stop of the discharge lamp 1 by repeating the oscillation and stop of the inverter circuit 3. In addition to notifying that, after a predetermined time has elapsed, oscillation is stopped and the stopped state is maintained,
We try to prevent power loss.

Even in this circuit, when there is no load, the output of the detection circuit is maintained in that state even after the oscillation is stopped, so that the oscillation stopped state is maintained. That is, under no load, the voltage at the point Y of the abnormality detection circuit 7 becomes 0 V, and similarly to the above, the transistor Q ₁₆ is turned off, the transistor Q ₁₂ is turned on, and the charge of the capacitor C ₁₄ is rapidly discharged, Comparator CP ₄
Is set to the L level, the preheat switch 6 is closed, and the transistor Q ₁₀ is turned off and the transistor Q ₉ is turned on by the potential of 0V at the point Y to turn on the inverter circuit 3.
Stop the oscillation of. Here, after the activation pulse oscillation stop by the activation circuit 2, always given to the transistor Q _2, since the discharge lamp l _1, l ₂ is disconnected, the potential of the point Y does not start not rise. Therefore, in the case of no load, the intermittent operation does not occur like the end of the life of the discharge lamp, and after detecting the abnormality, the inverter circuit 3 stops oscillating,
That state will be maintained.

In each embodiment, the timer circuit is a so-called CR.
I used a circuit, but it goes without saying that there is no problem with a counter.

[Advantages of the Invention] The present invention relates to a DC power supply, an inverter circuit that converts the output of the DC power supply into a high frequency by the ON / OFF operation of a switching element, a discharge lamp that is lit by the high frequency output from the inverter circuit, and An abnormality detection circuit that detects the half-wave lighting state at the end of the life of the discharge lamp and outputs an abnormality detection signal when the half-wave lighting state and an abnormality non-detection signal when the lighting state is normal First output control means for stopping the output of the inverter circuit only when receiving a circuit abnormality detection signal, and at least a plurality of predetermined times,
A second output control means for stopping the output of the inverter circuit when the output of the abnormality detection circuit is received and for holding the stopped state until the power supply from the DC power supply is cut off. Therefore, the half-wave lighting state at the end of the life of the discharge lamp is detected by the abnormality detection circuit, and the output of the inverter circuit is stopped and released by the first output control means that receives the abnormality detection signal from the abnormality detection circuit. Turn off the light output,
The operation of receiving the abnormality non-detection signal to start the normal lighting start by the stop of the output of the discharge lamp is repeated, and the repeated operation of the output stop and the release is repeated at least once, so that the discharge lamp is restarted. Blinks repeatedly to inform the user that the discharge lamp is at the end of life, and the second output control means can prevent electrical loss, and the reliability can be improved. The effect is also improved.

[Brief description of drawings]

1 (a) and 1 (b) are a block diagram and a flow chart of an embodiment of the present invention, FIG. 2 is an operation waveform diagram of the same, FIG. 3 is a concrete circuit diagram of another embodiment of the same, and FIG. Is an operation explanatory diagram of the same as above, FIG. 5 is an operation waveform diagram of the same as above, FIG. 6 is an equivalent basic circuit diagram of the above discharge lamp when the discharge lamp is normally lit, and FIG. 7 is an operation waveform diagram of the same as above.
Figures (a) and (b) are equivalent basic circuit diagrams of the discharge lamp at the end of its life,
FIG. 9 (a) is an equivalent basic circuit diagram when multiple lights are lit up,
FIG. 9 (b) is an equivalent circuit diagram of the above discharge lamp, FIG. 10 is an equivalent basic circuit diagram in the case of multiple lighting of the above, and FIG. 11 is a specific circuit diagram of a conventional example. 3 is an inverter circuit, 7 is an abnormality detection circuit, 9 is a timer circuit, 15 is a first output control means, 16 is a second output control means, and 1 is a discharge lamp.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Taishi Okamoto 1048, Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Works, Ltd. (72) Masataka Mitani, 1048, Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Works, Ltd.

Claims (1)

[Claims] 1. A DC power supply, an inverter circuit for converting the output of the DC power supply into a high frequency by the on / off operation of a switching element, a discharge lamp lit by the high frequency output from the inverter circuit, and a discharge lamp of the discharge lamp. An abnormality detection circuit that detects the half-wave lighting state at the end of life and outputs an abnormality detection signal when the half-wave lighting state and an abnormality non-detection signal when the lighting state is normal, and an abnormality of the abnormality detection circuit First output control means for stopping the output of the inverter circuit only when receiving the detection signal, and stopping the output of the inverter circuit when receiving the output of the abnormality detection circuit at least a plurality of predetermined times. A discharge lamp lighting device, comprising: a second output control unit that holds this stopped state until the power supply from the DC power supply is cut off.