JP3356233B2 - Discharge lamp lighting device and lighting device - Google Patents

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 and a lighting device capable of detecting the end of life of a discharge lamp.

[0002]

2. Description of the Related Art When a discharge lamp such as a fluorescent lamp reaches the end of its life, it often exhibits a half-wave discharge. In such a case, an excessive current flows due to the direct current component, and the switching element is destroyed and is opened or short-circuited. Further, as a secondary disaster, the ballast is damaged due to abnormal temperature rise, smoke or fire occurs. In addition, as a result of passing an excessive current through the discharge lamp, if the base is made of plastics, the base may be abnormally heated and melted.

In order to solve the problem that occurs at the end of the life of the discharge lamp by detecting the end of the life of the discharge lamp early and reliably and controlling the operation of the ballast, a discharge lamp has been put to practical use. ing.

FIG. 14 is a circuit conceptual diagram of a conventional discharge lamp lighting device of this type described in Japanese Patent Application Laid-Open No. 4-39895. The discharge lamp 142 is turned on by the high-frequency generation means 141, and a voltage detection means 143 for detecting the voltage between both ends of the discharge lamp 142, a current detection means 144 for detecting positive and negative current values flowing through the discharge lamp 142, Is provided. The output of the current detecting means 144 is compared by the comparing means 145, and when the positive / negative difference becomes a predetermined value or more,
The discharge lamp 142 is determined to be at the end of its life when the output of the voltage detecting means 143 becomes equal to or more than a predetermined value, and the output of the high frequency generating means 141 is controlled.

Japanese Patent Laid-Open Publication No. Hei 4-98796 also discloses a discharge lamp lighting device similar to the above-mentioned conventional example.

[0006] Further, there has been conventionally known an arrangement in which the end of life is detected only by one of the lamp voltage and the lamp current of the discharge lamp.

[0007]

However, in the above-mentioned prior art, when a plurality of types of discharge lamps having different load characteristics are configured to be lit by discharge stabilizing means having the same specification, the type of the discharge lamp may be different. If the values are different, the load characteristics are different, so that the values of the lamp current and the lamp voltage are different from each other, so that the sensitivity of the end-of-life determination is greatly shifted. That is, if the sensitivity is set in accordance with the load characteristics of any type of discharge lamp, the end of life cannot be accurately detected with other types of discharge lamps. This is shown in FIG.
3 will be described in detail. That is, FIG. 2 is a graph showing changes in lamp current during the life of some types of discharge lamps. Rapid start type fluorescent lamp FLR40, F
LR40 / 36 and compact fluorescent lamp FPL
The difference between 36 and a total of three types of characteristics can be understood from the graph.
The case where the end of life is determined by detecting a change in lamp current will be described as an example.
, It is determined that the end of life is reached, and the life can be accurately determined with the rapid start fluorescent lamp FLR40 / 36. However, in the case of the compact fluorescent lamp FPL36, it is erroneously determined that the end of life is at a stage substantially before the end of life. Conversely, in the case of the rapid start type fluorescent lamp FLR40 / 36, the end of life cannot be determined.

FIG. 3 is a graph showing lamp voltage changes over the life of some types of discharge lamps. The type of the discharge lamp is the same as in FIG. When the end of life is determined from this graph according to the lamp voltage detection signal, the tendency is opposite to that in FIG. 2, but there is basically the same problem as in FIG.

Therefore, it is conceivable to adjust the sensitivity each time according to the type of discharge lamp used, but it is cumbersome and not practical. SUMMARY OF THE INVENTION It is an object of the present invention to provide a discharge lamp lighting device and a lighting device in which the sensitivity is automatically adjusted regardless of the type of discharge lamp that is allowed in advance.

[0010]

According to a first aspect of the present invention, there is provided a discharge lamp lighting device, comprising: a discharge stabilizing means having an input terminal connected to a power supply and an output terminal connected to the discharge lamp; and a half-wave discharge flowing at the end of life of the discharge lamp. A lamp current detecting means capable of detecting a current, a lamp voltage detecting means detecting a lamp voltage of a discharge lamp, and a discharge lamp reaching the end of its life according to the output of one of the lamp voltage detecting means and the lamp current detecting means. And a control means for controlling lighting of the discharge lamp in accordance with the output of the end-of-life determination means, wherein the determination level is changed according to the other output, and It is characterized by having.

According to a second aspect of the present invention, there is provided a discharge lamp lighting device, comprising: a discharge stabilizing means having an input terminal connected to a power supply; a discharge lamp lit by an output of the discharge stabilizing means; and a half-wave discharge current flowing at the end of life of the discharge lamp. The discharge lamp has reached the end of its life according to the output of either the detectable lamp current detection means, the lamp voltage detection means for detecting the lamp voltage of the discharge lamp, or one of the lamp voltage detection means and the lamp current detection means. And a control means for controlling lighting of the discharge lamp in accordance with the output of the end-of-life determining means, the end-of-life determining means configured to change the determination level according to the other output. It is characterized by doing.

According to a third aspect of the present invention, there is provided a discharge lamp lighting device comprising: an electronic discharge stabilizing means having an input terminal connected to a power supply; a fluorescent lamp lit by an output of the electronic discharge stabilizing means; Lamp current detecting means capable of detecting a wave discharge current, a lamp voltage detecting means for detecting a lamp voltage of a fluorescent lamp, and a fluorescent lamp at the end of its life according to the output of one of the lamp voltage detecting means and the lamp current detecting means. And a control for controlling the electronic discharge stabilizing means in accordance with the output of the end-of-life determining means, wherein the determining level is changed according to the other output. And means.

According to a fourth aspect of the present invention, there is provided a discharge lamp lighting device, comprising: an electronic discharge stabilizing means having an input terminal connected to a power supply; a discharge lamp lit by an output of the electronic discharge stabilizing means; Lamp current detecting means capable of detecting a wave discharge current, a lamp voltage detecting means for detecting a lamp voltage of a discharge lamp, and judging that the discharge lamp has reached the end of its life according to an output of the lamp current detecting means, and The end-of-life determining means configured to change the determination level in accordance with the output of the lamp voltage detecting means, and control means for controlling the electronic discharge stabilizing means in accordance with the output of the end-of-life determining means. It is characterized by:

According to a fifth aspect of the present invention, a discharge stabilizing means having an input terminal connected to a power source, a discharge lamp lit by an output of the discharge stabilizing means, and a half-wave discharge current flowing at the end of life of the discharge lamp can be detected. Lamp current detecting means, a lamp voltage detecting means for detecting the lamp voltage of the discharge lamp, and judging that the discharge lamp has reached the end of its life according to the output of one of the lamp voltage detecting means and the lamp current detecting means. And a control means for controlling lighting of the discharge lamp in accordance with the output of the end-of-life determining means, wherein the determination level is changed according to the other output. A discharge lamp lighting device; and a lighting device main body provided with the discharge lamp lighting device.

[0015]

According to the first and second aspects of the invention, the discharge lamp is stably lit by the discharge stabilizing means, the lamp current is detected by the lamp current detecting means, and the lamp voltage is detected by the lamp voltage detecting means. A predetermined detection signal of either the lamp current or the lamp voltage is input to the end-of-life determining means as a signal to be determined. The end-of-life determining means determines the end of life when the magnitude of the input signal is a predetermined value, and otherwise determines that the end of life is not reached. The detection signal of the other of the lamp current and the lamp voltage is input to the end-of-life determining means so as to change or correct the determination level of the end-of-life determining means. In other words, no matter which discharge lamp is used in the range of discharge lamps of the type allowed in advance, the sensitivity of the end-of-life determination is automatically adjusted to be within the allowable range. When the end of life is determined, the control means controls the lighting of the discharge lamp to prevent the occurrence of a disaster in advance.

According to the third aspect of the present invention, the same operation as in the first and second aspects of the present invention is performed for determining the end of life. However, when the electronic discharge stabilizing means is used as the discharge stabilizing means and the end of life is determined, The control means controls the electronic stabilization means. Therefore, lighting of the fluorescent lamp is controlled so as to prevent occurrence of a disaster.

According to the fourth aspect of the invention, the operation is the same as that of the third aspect except that the end of life is determined by the lamp current detection signal and the sensitivity of the life determination is adjusted by the lamp voltage detection signal.

According to a fifth aspect of the present invention, there is provided a lighting device having the same function as the discharge lamp lighting device of the first aspect.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a conceptual diagram of a circuit according to the present invention. In the figure, reference numeral 11 denotes a power supply such as a commercial AC power supply, 12 denotes a discharge stabilizing unit such as an electronic stabilizing unit, and 13 denotes a discharge lamp such as a fluorescent lamp. The input end of the discharge stabilizing means 12 is connected to the power supply 11, and the output end is connected to the discharge lamp 13. 14 is a lamp voltage detecting means connected in parallel to the discharge lamp 13 to detect the lamp voltage of the discharge lamp, and 15 is connected in series with the discharge lamp 13 to directly or indirectly detect the lamp current of the discharge lamp 13 Lamp current detecting means 16; end-of-life determining means 16; and control means 17; A predetermined one of a lamp voltage detection signal and a lamp current detection signal is input to the end-of-life determining means 16 as a signal for determining the life. The other detection signal is input to change or correct the determination sensitivity.

Next, the operation of the embodiment shown in FIG. 1 will be described. Electric energy is supplied to the discharge lamp 13 from the power supply 11 via the discharge stabilizing means 12, and the discharge lamp 13 is turned on. The lamp voltage of the discharge lamp 13 is monitored by the lamp voltage detecting means 14, and the lamp current is monitored by the lamp current detecting means 15. When the preselected value of the lamp voltage and lamp current of the discharge lamp 13 reaches a preset value, the end-of-life determining means 16 determines that it is the end of life. When the end-of-life determining means 16 determines that the end of life is reached, the control means 17 operates to control the lighting of the discharge lamp 13.

On the other hand, the output of the other detecting means 15 or 14 is input to the life determining means 16 so as to change or correct the sensitivity of the life determining means 16.

Next, the correction of the determination sensitivity will be described.
As shown in FIGS. 2 and 3, the lamp current and lamp voltage of the discharge lamp gradually increase during the life. The discharge lamp of the type having a large change in the lamp current has a relatively small change in the lamp voltage.

Conversely, a discharge lamp of a type having a small change in lamp current has a large change in lamp voltage. From each figure, it can be understood that the lamp current and the lamp voltage have a complementary relationship.

A case will now be described in which the end of life is determined based on the lamp current detection signal. For example, when the compact fluorescent lamp FPL36 is used, the lamp current detection signal has a high signal level in the same life process, but the lamp voltage detection signal has a low signal level. Therefore, the judgment sensitivity of the life judgment means 16 depends on the latter signal level. Automatically lowered. Of course, rapid start type fluorescent lamp FL
It can be easily understood that in the case of R40, the determination sensitivity of the life determining unit 16 can be increased. In the case of the rapid start type fluorescent lamp FLR40 / 36, it is an intermediate level between the above two. As described above, the sensitivity of the end-of-life determination is automatically corrected according to the type of the discharge lamp.

FIG. 4 is a circuit diagram showing an example of the lamp voltage detecting means. In the figure, 41 and 42 are voltage-dividing resistors connected in series between both ends of the discharge lamp 13, 43 and 44 are capacitors and diodes connected in series between both ends of the resistor 42, and 45 is a capacitor 43 and a diode 44. A diode whose one end is connected in series with the diode 44 in the forward direction at the connection point.
45 is a smoothing capacitor connected in parallel to 45. The lamp voltage detection signal is obtained from both ends of the capacitor 46.

The lamp voltage of the discharge lamp is divided by resistors 41 and 42, the voltage drop of the resistor 42 is double-voltage rectified, and a lamp voltage detection signal is obtained from the other end of the diode 45. For example, it is input to the end-of-life determining means 16 as a determination sensitivity correction. FIG. 5 is a circuit diagram showing another example of the lamp voltage detecting means. In this example, one lamp voltage detecting means is provided for two discharge lamps 13 and 13 which are lit in series. Capacitors 51 and 52 are connected in series between the outer ends of the discharge lamps 13 and 13 as voltage dividing elements. Other configurations are the same as those in FIG. 6, and therefore, the same portions are denoted by the same reference numerals and description thereof is omitted. The operation is basically the same as in FIG.

FIG. 6 is a circuit diagram showing an example of the lamp current detecting means 15. In the figure, 61 is a capacitor inserted in series in the discharge circuit, and 62 and 63 are resistors, which divide the terminal voltage of the capacitor 61 equally. Diodes 64 and 65 denote DC voltages of different polarities, which appear between the terminals of the resistors 62 and 63, of the same polarity, and guide them to the output side. 66 is a smoothing capacitor. This example is suitable for a half-bridge inverter shown in FIG.

When a half-wave discharge occurs at the end of the life of the discharge lamp, a positive or negative half-wave voltage appears across the capacitor 61. In the case of the polarity shown in FIG. To charge the capacitor 66 to the polarity shown. If the voltage appearing across capacitor 61 is the opposite of that shown, the terminal voltage of resistor 63 will pass through diode 65 and also charge capacitor 66 to the polarity shown. Therefore, when a half-wave discharge occurs, a lamp current detection signal is input to the end-of-life determination means 16 regardless of its polarity, for example, as a signal for end-of-life determination.

FIG. 7 is a circuit diagram showing another example of the lamp current detecting means 15. In the figure, reference numeral 71 denotes a current transformer inserted in series with the capacitor 61, and other parts are the same as those in FIG.
Therefore, the same reference numerals are given and the description is omitted.
This example is suitable for a single-type inverter of FIG. 9 described later. By detecting a half-wave discharge across the current transformer 71, a DC component flows through the current transformer 71, thereby preventing abnormal operation of the inverter.

FIG. 8 is a circuit diagram showing an example of the end-of-life determining means 16. In the figure, reference numeral 81 denotes a comparator. A lamp current detection signal is input to an input terminal a of the comparator, and an end-of-life determination output is sent to the control means 17 from an output terminal. The output of the correction circuit 82 is input to the reference signal terminal b. The correction circuit 82 is mainly composed of a transistor 82 a whose degree of conduction changes according to the output of the lamp voltage detection means 14. The collector of the transistor 82a is connected to the reference signal terminal b of the comparator 81. Incidentally, 82b and 82 in the figure
c, 82d and 82e are resistors, and 82f is a Zener diode.

When the output of the lamp voltage detecting means 14 is small in accordance with the type of the discharge lamp, the base current of the transistor 82a becomes small, so that the degree of conduction is small and the collector potential rises. Therefore, the reference signal applied to the reference signal terminal b rises.

According to the type of the discharge lamp, even if the detection signal of the lamp current detection means 15 input to the input terminal a increases, the reference signal also increases, so that the comparator 82 generates an output. In other words, the lamp current detection signal must further rise. In other words, the determination sensitivity of the end-of-life determination unit 16 becomes relatively weak due to the lamp voltage detection unit 14 and the correction circuit 82. Conversely, when the output of the lamp voltage detecting means 14 increases according to the type of the discharge lamp, the base current of the transistor 82a increases, and the conductivity increases, so that the collector potential decreases. Therefore, the reference signal applied to the reference signal terminal b decreases. Therefore, even if the output of the lamp current detecting means 15 relatively decreases, the end of life can be properly determined because the determination sensitivity of the end of life determining means 16 is sharpened by the decrease of the reference signal. As described in detail above, when the end-of-life judgment is performed based on one of the lamp current and the lamp voltage, the judgment sensitivity is automatically corrected by the other. Always perform an appropriate judgment operation.

FIG. 9 is a circuit diagram showing an example in which the discharge stabilizing means 12 is constituted by an electronic ballast. The figure shows a one-piece inverter, in which 91 is a power supply 11
Rectifier circuit for rectifying and smoothing the alternating current of 92, 92 is a smoothing circuit,
93 is a main switching element of the inverter. 94 is an output transformer, 94a is its primary winding, 94b is a secondary winding, and 95 is a capacitor connected in parallel with the primary winding 94a to form a resonance circuit together with the output transformer. 9
Reference numeral 6 denotes a current transformer connected in series with the secondary winding 94b.
It supplies necessary energy for causing the main switching element 93 to self-oscillate, and gives switching timing. 97
Is a capacitor inserted in the excitation circuit of the switching element 93 and determines the oscillation frequency.

FIG. 10 is a circuit diagram showing another example of the discharge stabilizing means 12. This is an electronic ballast having a half-bridge inverter. That is, a pair of switching elements 101 and 102 are connected in series to a DC power supply, and an inductor 103 is connected in series between a connection point between the switching elements 101 and 102 and a connection point between the switching element 102 and the DC power supply. The discharge lamp 13 is connected, for example, via an output transformer (not shown) 104. 104 denotes switching elements 101 and 102
Are alternately switched. In the figure, the same parts as those in FIG. 9 are denoted by the same reference numerals, and description thereof will be omitted. FIG. 11 is a circuit diagram showing an example of the control means 17 in FIG. The control means 17 includes a light emitting diode 111 of a photocoupler that responds to the determination output of the end-of-life determining means 16, a phototransistor 112 of a photocoupler that turns on in response to the light emission, and an on when the phototransistor 112 is off. Transistor 11
3 as a main component.

On the other hand, in FIG. 11, the discharge stabilizing means 12 is a one-piece inverter shown in FIG. 9, but divides the capacitor 97 of the excitation circuit into two capacitors 97a and 97b connected in parallel. And the transistor 113 is connected in series. 11 in the figure
A capacitor 4 is charged from a DC power supply via a resistor 115. The phototransistor 112 and a series circuit of resistors 116 and 117 are connected in parallel with the capacitor 11. A capacitor 118 is connected in parallel with the resistor 117, and the base of the transistor 113 is connected via the resistor 119 so that the transistor 113 is turned on and off in accordance with the terminal voltage of the capacitor.
8 is connected to one end.

In the present invention, the discharge stabilizing means is shown in FIGS.
However, the present invention is not limited to this, and various discharge stabilizing means can be used.

Next, the operation of the control means 17 shown in FIG. 11 will be described. When a judgment output is obtained from the end-of-life judging means 16 due to a predetermined one of the lamp current and the lamp voltage, for example, the value of the lamp current exceeds a set value, the light emitting diode 111 of the photocoupler emits light. Accordingly, the phototransistor 112 is turned on. Thus, the potential of the capacitor 118 decreases, and the transistor 113 is turned off from on. As a result, the capacitor 97b is opened, so that the oscillation frequency of the single inverter increases. As a result, the load current of the inverter, that is, the lamp current is greatly reduced. That is, lighting of the discharge lamp is controlled, and various disasters accompanying the occurrence of half-wave discharge at the end of life are prevented.

FIG. 12 is a circuit diagram showing another example of the control means 17. This example is suitable for a discharge stabilizing means mainly composed of a half-bridge inverter shown in FIG. 10, and uses an integrated circuit 121. The integrated circuit 121 is configured to use various protection devices and those used for controlling the oscillation of the inverter also for end-of-life protection. That is, the transistor 12 turned on by the output of the end-of-life determining means
2. A signal is inputted between predetermined control input terminals c and d of the integrated circuit 121 via the resistors 123 and 124 by turning on the switch. As a result, a control signal is sent from the output terminal e of the integrated circuit 121, and the drive circuit of the inverter greatly reduces the output of the inverter by this control signal or stops the operation if necessary.

FIG. 13 is a front view showing an example of the illumination device of the present invention. In the figure, 131 is a lighting device main body, 13
Reference numerals 2 and 132 are sockets, and 133 is a discharge lamp lighting device. The lighting device is controlled to blink by a switch (not shown) provided inside the device body or a switch (not shown) provided outside the body.

The present invention is not limited to the above description, but allows various modifications. For example, a switch may be interposed between the discharge stabilizing means and the discharge lamp or between the power supply and the discharge stabilizing means, and at the end of life, the switch may be opened by a control signal to turn off the discharge lamp. In addition to turning off the discharge lamp substantially, the discharge of the discharge lamp may be controlled so that the end of life can be indicated, for example, dimming or intermittent discharge may be performed. As the discharge stabilizing means, not only the electronic discharge stabilizing means but also a discharge stabilizing means comprising an iron core and a coil may be used. In the case of the electronic discharge stabilizing means, it is not limited to a single stone type or a half bridge type. For example, an arbitrary inverter such as a full bridge type and a parallel type may be used. The power supply may be any power supply such as a DC power supply, for example, a battery power supply, other than the commercial AC power supply. Further, the number of discharge lamps is arbitrary. The discharge lamp allows not only a fluorescent lamp but also other discharge lamps such as a germicidal lamp.

[0042]

The present invention has the following effects because of the configuration and operation described above in detail.

According to the first to fifth aspects of the present invention, the end of life is determined by one of the lamp current and the lamp voltage, and the sensitivity of the determination is automatically changed or corrected by the other. Even if they differ, the end-of-life judgment can be appropriately performed, and therefore the present invention can be applied to a plurality of types of discharge lamps without changing the specifications of the discharge stabilizing means.

In particular, according to the third aspect of the invention, when the end of life is detected, the lighting of the discharge lamp is controlled by controlling the electronic discharge stabilizing means, so that the control is easy and the configuration can be simplified.

In particular, according to the invention of claim 4, in addition to the effect of the claim, the end of life is determined by the lamp current,
The determination sensitivity can be changed depending on the lamp voltage.

In particular, according to the invention of claim 5, it is possible to provide a lighting device having the same effect as that of the invention of claim 1.

[Brief description of the drawings]

FIG. 1 is a circuit conceptual diagram showing one embodiment of a discharge lamp lighting device of the present invention.

FIG. 2 is a graph showing a change in lamp current during the life of a discharge lamp.

FIG. 3 is a circuit diagram showing a change in lamp voltage during the life of the discharge lamp.

FIG. 4 is a circuit diagram showing one example of a lamp voltage detecting means of the present invention.

FIG. 5 is a circuit diagram showing another example of the lamp voltage detecting means of the present invention.

FIG. 6 is a circuit diagram showing one example of a lamp current detecting means of the present invention.

FIG. 7 is a circuit diagram showing another example of the lamp current detecting means of the present invention.

FIG. 8 is a circuit diagram showing an example of the end-of-life determining means of the present invention.

FIG. 9 is a circuit diagram showing an example of the discharge stabilizing means of the present invention.

FIG. 10 is a circuit diagram showing another example of the discharge stabilizing means of the present invention.

FIG. 11 is a circuit diagram showing an example of the control means of the present invention.

FIG. 12 is a circuit diagram showing another example of the control means of the present invention.

FIG. 13 is a front view showing an example of the illumination device of the present invention.

FIG. 14 is a circuit diagram showing a conventional discharge lamp lighting device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Power supply 12 Discharge stabilizing means 13 Discharge lamp 14 Lamp voltage detecting means 15 Lamp current detecting means 16 End of life determining means 17 Control means

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Claims (5)

(57) [Claims] 1. A discharge stabilizing means having an input terminal connected to a power supply and an output terminal connected to a discharge lamp; lamp current detection means capable of detecting a half-wave discharge current flowing at the end of life of the discharge lamp; Lamp voltage detecting means for detecting a lamp voltage; determining that the discharge lamp has reached the end of its life in accordance with the output of one of the lamp voltage detecting means and the lamp current detecting means, and determining in accordance with the other output End-of-life determining means configured to change the level; control means for controlling lighting of the discharge lamp in accordance with an output of the end-of-life determining means;
A discharge lamp lighting device comprising: 2. A discharge stabilizing means having an input terminal connected to a power supply; a discharge lamp lit by an output of the discharge stabilizing means; a lamp current detecting means capable of detecting a half-wave discharge current flowing at the end of life of the discharge lamp. Lamp voltage detecting means for detecting the lamp voltage of the discharge lamp; determining that the discharge lamp has reached the end of its life in accordance with one of the outputs of the lamp voltage detecting means and the lamp current detecting means; And a control means for controlling lighting of the discharge lamp in accordance with the output of the end-of-life determining means. Lighting device. 3. An electronic discharge stabilizing means having an input terminal connected to a power supply; a fluorescent lamp turned on by an output of the electronic discharge stabilizing means; a lamp capable of detecting a half-wave discharge current flowing at the end of life of the discharge lamp. Current detection means; lamp voltage detection means for detecting the lamp voltage of the discharge lamp; and determining that the discharge lamp has reached the end of its life according to the output of one of the lamp voltage detection means and the lamp current detection means; And end-of-life determination means configured to change the determination level in accordance with the other output; and control means for controlling the electronic discharge stabilization means in accordance with the output of the end-of-life determination means. Discharge lamp lighting device. 4. An electronic discharge stabilizing means having an input terminal connected to a power supply; a discharge lamp lit by an output of the electronic discharge stabilizing means; a lamp capable of detecting a half-wave discharge current flowing at the end of life of the discharge lamp. Current detecting means; lamp voltage detecting means for detecting a lamp voltage of the discharge lamp; determining that the discharge lamp has reached the end of its life according to the output of the lamp current detecting means;
And end-of-life determining means configured to change the determination level in accordance with the output of the lamp voltage detecting means; and control means for controlling the electronic discharge stabilizing means in accordance with the output of the end-of-life determining means. A lighting device for a discharge lamp, comprising: 5. A discharge stabilizing means having an input terminal connected to a power supply, a discharge lamp lit by an output of the discharge stabilizing means, and a lamp current detecting means capable of detecting a half-wave discharge current flowing at the end of life of the discharge lamp. A lamp voltage detecting means for detecting a lamp voltage of a discharge lamp, and judging that the discharge lamp has reached the end of its life according to the output of one of the lamp voltage detecting means and the lamp current detecting means, and the other output A discharge lamp lighting device comprising: an end-of-life determining means configured to change the determination level in accordance with the control signal; and control means for controlling lighting of the discharge lamp in accordance with an output of the end-of-life determining means; A lighting device main body provided with a discharge lamp lighting device;