JP2002158097A - Discharge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device which enables to detect surely breaking of a core wire of the discharge lamp without reducing an illumination control width. SOLUTION: An inverter part 1 is a circuit which outputs DC input voltage Vin converted to AC voltage Vac, and is equipped with a plurality n of output terminals To1 to Ton. The AC voltage Vac is given as a wave form having one period τ of a summation of an on-time alternating with a given frequency and amplitude, and an off-time of the amplitude being a low level. A peak value detecting part 3 detects a peak value of a total current Io from Io1 to Ion flowing at discharge lamps 51 to 5n connected to each output terminal To1 to Ton as a voltage value. An alarm signal generating part 4 generates an alarm signal S3 from a peak value detecting signal S2 supplied from the peak value detecting part 3.

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 for lighting a discharge lamp such as a cold cathode tube.

[0002]

2. Description of the Related Art In a liquid crystal display used for a personal computer or the like, light must be emitted from behind a liquid crystal plate. A discharge lamp such as a cold cathode tube is used as a light irradiating means for that purpose.

As a discharge lamp lighting device for lighting a discharge lamp, a self-excited oscillation type inverter is generally used. As the self-excited oscillation method, a Loyer oscillation circuit is mainly used from the viewpoints of simple circuit configuration, operation stability, and the like. An AC voltage is generated by the Loyer oscillation circuit, and the AC voltage is applied between the electrodes of the discharge lamp to light it.

One of the problems in lighting a plurality of discharge lamps by using the above-described discharge lamp lighting device is that the disconnection failure of the plurality of discharge lamps is solved by a simple circuit configuration.
There is a problem how to reliably detect. As means for detecting the disconnection of the discharge lamp, a configuration in which a disconnection detection circuit is added to each discharge lamp can be considered. However, in this configuration, the number of disconnection detection circuits increases.

[0005] As another method of detecting a disconnection failure, a configuration in which a common disconnection detection circuit is provided for the discharge lamp to simplify the circuit configuration of the disconnection detection circuit is also conceivable. However, in this configuration, the total current value Io at the time of minimum luminance (at the time of minimum light control), that is, the current Io obtained by summing the tube currents flowing through the respective discharge lamps at the time of minimum luminance.
If o becomes smaller than the tube current Is1 flowing through one of the discharge lamps at the time of maximum luminance (at the time of maximum dimming), it is no longer possible to detect the centering.

For example, when two discharge lamps are used, the current flowing through each of the discharge lamps at the time of the minimum luminance is 2 m.
A (rms), the total current Io at the time of the minimum luminance is 4
mA (rms). On the other hand, if the current Is1 flowing through each of the discharge lamps at the maximum luminance is 6 mA (rms), then Io <Is1.

[0007] Under the above-mentioned conditions, when one of the discharge lamps is disconnected at the maximum luminance, the current becomes 6 mA (rms). This current value of 6 mA (rms) corresponds to the total current Io = 4 at the time of the minimum dimming.
Since it is larger than mA (rms), it cannot be used as the core of the discharge lamp. That is, the disconnection failure cannot be detected.

[0008] In order to detect the disconnection, the total current Io at the minimum luminance is set to a value larger than the current Is1 = 6 mA (rms) flowing through each of the discharge lamps at the maximum luminance, for example.
7 mA (rms) must be selected. This means that the tube current value at the minimum luminance is raised, and the dimming variable width between the minimum luminance and the maximum luminance is reduced.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a discharge lamp lighting device capable of reliably detecting disconnection of a discharge lamp with a simple circuit configuration.

Another object of the present invention is to provide a discharge lamp lighting device capable of reliably detecting disconnection of a discharge lamp without reducing the dimming variable width.

[0011]

To solve the above-mentioned problems, a discharge lamp lighting device according to the present invention includes an inverter, a peak value detector, and an alarm signal generator. The inverter unit is a circuit that converts a DC input voltage into an AC voltage and outputs the converted voltage, and includes a plurality of output terminals. The AC voltage is a sum of an on-time alternating at a predetermined frequency and a predetermined amplitude and an off-time when the amplitude is at a low level is 1
It is given by a waveform that is a period.

The peak value detector converts a peak value of a total sum of currents flowing through a plurality of discharge lamps connected to each of the output terminals into a voltage value and detects the voltage value. The alarm signal generation unit generates an alarm signal from a peak value detection signal supplied from the peak value detection unit.

In the discharge lamp lighting device according to the present invention, the inverter section is a circuit for converting a DC input voltage into an AC voltage and outputting the same, and has a plurality of output terminals.
A plurality of discharge lamps can be individually connected to each of the plurality of output terminals, and the plurality of discharge lamps can be simultaneously driven and lit by one inverter unit. Therefore, since a plurality of discharge lamps can be driven at the same frequency,
A plurality of discharge lamps can be lit at the same brightness without accompanying a brightness variation due to a difference in frequency.

Moreover, since the AC voltage is given as a waveform having one cycle of the ON time alternating at a predetermined frequency and a predetermined amplitude and the OFF time at which the amplitude becomes a low level,
By controlling the duty ratio determined by the ON time and the OFF time, dimming control can be given to the discharge lamp.

As described above, the AC voltage supplied to the discharge lamp is given by an alternating waveform with a predetermined amplitude.
When no core failure has occurred in any of the discharge lamps, the peak value of the sum of the currents flowing through the discharge lamps is a constant value regardless of the dimming. Only the duty ratio changes between the minimum luminance (minimum dimming) and the maximum luminance (maximum dimming).

Since the peak value detector detects the peak value of the sum of the currents flowing through the discharge lamps as a voltage value, if any of the discharge lamps does not suffer from a core failure,
In the entire dimming range from the minimum luminance to the maximum luminance, a current detection signal indicated by a constant voltage value is obtained.

The alarm signal generation section generates an alarm signal from the peak value detection signal supplied from the peak value detection section. If there is no disconnection failure in any of the discharge lamps, the peak value detection unit can obtain a peak value detection signal indicated by a constant voltage value in the entire dimming range from the minimum luminance to the maximum luminance. The alarm signal generator can compare the peak value detection signal with the reference value and generate a signal without disconnection.

In the event that a core failure has occurred in any of the discharge lamps,
Since the current stops flowing to the discharge lamp that caused the core failure,
The peak value of the sum of the currents flowing through the discharge lamp is reduced by that amount. The peak value detector detects the peak value of the sum of the currents,
Convert to voltage value and detect. Also in this case, the peak value of the total current is a constant value regardless of the dimming,
Only the duty ratio changes between the minimum luminance and the maximum luminance.

The alarm signal generation section generates an alarm signal indicating that there is a disconnection from the peak value detection signal. Specifically, the peak value detection signal is compared with the reference value, and it is determined that there is a disconnection. Therefore, the alarm signal generation unit only needs to have a reference value corresponding to the tube current of the discharge lamp. Therefore, the disconnection of the discharge lamp can be reliably detected without reducing the variable dimming width.

Further, since only one peak value detecting section and one alarm signal generating section need to be provided for a plurality of discharge lamps, the disconnection of the discharge lamp can be reliably detected with a simple circuit configuration. .

Other objects, configurations and advantages of the present invention will be described in more detail with reference to the accompanying drawings. The accompanying drawings are merely examples.

[0022]

FIG. 1 is a block diagram showing the configuration of a discharge lamp lighting device according to the present invention. The illustrated discharge lamp lighting device includes an inverter unit 1, a peak value detection unit 3, and an alarm signal generation unit 4. The inverter unit 1 converts the DC input voltage Vin supplied to the input terminal Tin into the AC voltage Va.
This is a circuit for converting into c and outputting it, and has a plurality of n output terminals To1 to Ton. The AC voltage Vac is the sum of an on-time alternating at a predetermined frequency and a predetermined amplitude and an off-time at which the amplitude becomes a low level, for example, a zero level, is 1
It is given by a waveform having a period τ. The duty ratio of the AC voltage Vac can be set manually or automatically by a signal supplied from the duty adjustment unit 6.

The peak value detector 3 has output terminals To1 to T
on of the plurality of n discharge lamps 51 to 5n connected to each of
The peak value of the total sum Io of the current flowing through is detected as a voltage value. The total sum Io of the currents flowing through the discharge lamps 51 to 5n is Io = Io1 + Io2 +. . . . + Ion.

Each of the discharge lamps 51 to 5n is, for example,
A cold cathode tube, one end of which is the output terminal To of the inverter unit 1.
1 to Ton, and the other end is connected to a common terminal Tcom.

In the illustrated embodiment, an output current detector 2 is provided. The output current detection unit 2 includes discharge lamps 51 to 5
n is inserted into the power supply line on the low voltage side to which n is commonly connected, and the total sum Io of the currents flowing through the discharge lamps 51 to 5n connected to the output terminals To1 to Ton is converted to a voltage value. Output.

The peak value detection section 3 detects the peak value of the current detection signal S1 output as a voltage value from the output current detection section 2 as the peak value of the current sum Io.

The alarm signal generation section 4 generates an alarm signal S3 from the peak value detection signal supplied from the peak value detection section 3. The warning signal S3 is generated by comparing the peak value detection signal with a reference value.

In the illustrated embodiment, the current detection signal S1 output from the output current detection unit 2 is fed back to the inverter unit 1. The inverter unit 1 outputs the discharge lamps 51 to 5n based on the current detection signal S1 fed back from the output current detection unit 2, for example, by pulse width control or the like.
An operation is performed so as to supply a constant current to the device.

The inverter unit 1 is a circuit that converts a DC input voltage Vin supplied to an input terminal Tin into an AC voltage Vac and outputs the AC voltage Vac. The inverter unit 1 has a plurality of n output terminals To1 to To.
n, the plurality of n discharge lamps 51 to 5n are individually connected to each of the output terminals To1 to Ton, and the plurality of n discharge lamps 51 to 5n are simultaneously driven by one inverter unit 1. Can be turned on. Therefore, since the plurality of n discharge lamps 51 to 5n can be driven at the same frequency, the plurality of n discharge lamps 51 to 5n are lit at the same brightness without any brightness variation due to the difference in frequency. be able to.

In the illustrated embodiment, the output current detection circuit 2
Detects the current on the low potential side, so that the discharge lamps 51 to
Even if the leakage current differs due to a difference in the distribution capacitance in 5n, etc., the output current detection circuit 2 can detect a current reflecting the difference in the leakage current.

FIG. 2 is a waveform diagram for explaining the operation of the discharge lamp lighting device shown in FIG. 1 in the case where the discharge lamp disconnection failure does not occur. In the description with reference to FIG. 2, the number of discharge lamps is set to n = 2 and the
Are connected to two discharge lamps 51 and 52.

FIG. 2A shows a case where the discharge lamp 5
1 and 52, the sum of currents Io1 and Io2 (= Io
o1 + Io2), FIG. 2 (b) is a waveform diagram of a current detection signal S1 (voltage signal) output from the output current detection unit 2, and FIG. 2 (c) is a peak value output from the peak value detection unit 3. FIG. 7 is a waveform diagram of a detection signal S2 (voltage signal). FIG.
(D) is the total sum Io (= Io1 + Io) of the currents Io1 and Io2 flowing through the discharge lamps 51 and 52 in the case of the minimum luminance.
FIG. 2E is a waveform diagram of the current detection signal S1 (voltage signal) output from the output current detection unit 2, and FIG.
(F) is a waveform diagram of the peak value detection signal S2 (voltage signal) output from the peak value detection unit 3. AC voltage Vac
Is a waveform similar to the current waveform in FIG. 2A except for the phase.

First, referring to FIG. 2A, the total sum Io of the current is the sum of an on-time Ton1 alternating at a predetermined frequency and a predetermined amplitude, and an off-time Tof1 at which the amplitude becomes a low level (zero). It is given as a waveform with (Ton1 + Tof1) as one period τ. Therefore, the ON time Ton1 and the OFF time T
By controlling the duty ratio {Ton1 / (Ton1 + Tof1)} determined by ofl, dimming control can be given to the discharge lamps 51 to 5n.

AC voltage V supplied to discharge lamps 51 and 52
Since ac (see FIG. 1) is given as an alternating waveform with a predetermined amplitude, the sum of the currents flowing through the discharge lamps 51 and 52 when no disconnection failure occurs in any of the discharge lamps 51 and 52. The peak value of Io is a constant value regardless of the light control.

Therefore, as shown in FIGS. 2B and 2E, the output current detector 2 outputs a current having a constant peak value (voltage value) Vp1 regardless of the difference between the minimum luminance and the maximum luminance. The detection signal S1 is output. For the minimum luminance and the maximum luminance, the duty ratio is {Ton1 / (Ton1 + Tof1)} and {Ton1 /
2 / (Ton2 + Tof2)} (FIGS. 2A and 2D).
See).

Since the peak value detector 3 detects the peak value Vp1 of the sum Io of the currents flowing through the discharge lamps 51 and 52, if the discharge lamps 51 and 52 have not suffered from the disconnection failure, FIG. As shown in (c) and (f), the minimum brightness,
A peak value detection signal S2 indicated by a constant DC voltage value Vp1 is obtained between the maximum luminance and the maximum luminance.

The alarm signal generation section 4 converts the peak value detection signal S2 supplied from the peak value detection section 3 into an alarm signal S3.
Generate When the disconnection failure has not occurred in any of the discharge lamps 51 and 52, the peak value detection unit 3 obtains a peak value detection signal S2 having a constant voltage value Vp1 from the minimum luminance to the maximum luminance. From the alarm signal generator 4
Compares the peak value detection signal S2 with the reference value S4, and generates a signal without disconnection.

FIG. 3 is a waveform diagram for explaining the operation when a discharge lamp disconnection failure occurs in the discharge lamp lighting device shown in FIG. In the description with reference to FIG. 2, it is assumed that the number of discharge lamps is n = 2 and two discharge lamps 51 and 52 are connected to the inverter unit 1 for simplification of the description. FIG.
FIG. 3A is a waveform diagram of the sum Io (= Io1 + Io2) of the currents Io1 and Io2 flowing through the discharge lamps 51 and 52 in the case of the maximum luminance, and FIG. 3B is a current detection signal S1 output from the output current detection unit 2. FIG. 3C shows a peak value detection signal S2 output from the peak value detection unit 3;
FIG. 4 is a waveform diagram of (voltage signal). FIG. 3D shows the currents Io1 and Io1 flowing through the discharge lamps 51 and 52 in the case of the minimum luminance.
FIG. 3 is a waveform diagram of the sum Io (= Io1 + Io2) of o2, FIG.
3E is a waveform diagram of a current detection signal S1 (voltage signal) output from the output current detection unit 2, and FIG. 3F is a peak value detection signal S2 (voltage signal) output from the peak value detection unit 3.
FIG.

When a discharge failure occurs in the discharge lamp 51 among the discharge lamps 51 and 52, no current flows through the discharge lamp 51 in which the discharge failure has occurred.
Peak value decreases. Also in this case, the peak value of the current sum Io is a constant value regardless of the light control.

Therefore, as shown in FIGS. 3B and 3E, regardless of the difference between the minimum luminance and the maximum luminance, the output current detector 2 outputs a current having a constant peak value (voltage value) Vp2. The detection signal S1 is output. For the minimum luminance and the maximum luminance, the duty ratio is {Ton1 / (Ton1 + Tof1)} and {Ton1 /
2 / (Ton2 + Tof2)} (FIGS. 3A and 3D).
See).

The peak value detecting section 3 is provided with the signals shown in FIGS.
As shown in the figure, a constant DC voltage value Vp corresponding to the peak value (voltage value) Vp2 output from the output current detection unit 2
A peak value detection signal S2 having 2 is generated.

The alarm signal generator 4 compares the peak value detection signal Vp2 with a reference value (voltage value) S4, and generates an alarm signal S3 indicating that there is a break. After all, the alarm signal generator 4
Only needs to have a reference value corresponding to the tube currents of the discharge lamps 51 and 52, so that the disconnection of the discharge lamps 51 and 52 can be reliably detected without reducing the dimming variable width.

In addition, since only one peak value detecting section 3 and one alarm signal generating section 4 need to be provided for the discharge lamps 51 and 52, the discharge lamps 51 and 52 have a simple circuit configuration.
2 can be reliably detected. The same applies when the number of discharge lamps is expanded to n.

FIG. 4 is a circuit diagram showing a specific configuration example of the alarm signal generator 4 when the number of discharge lamps is n. In the illustrated embodiment, the alarm signal generation unit 4 includes n voltage comparison units 401 according to the number n of the discharge lamps 51 to 5n (see FIG. 1).
Ｎ40n. The peak value detection signal S2 obtained by the peak value detection unit 3 is commonly supplied to one of the input terminals of the voltage comparison units 401 to 40n. Further, reference values (voltage values) S41 to S4n to be compared with the peak value detection signal S2 are supplied to the other of the input terminals of the voltage comparison units 401 to 40n. The reference values S41 to S4n are, for example, S41>S42>. . . >
Different from each other as in S4n. And the discharge lamps 51 to
5n, the voltage comparator 401 generates a high-level (logical value 1) signal S31 when one of 5n has a disconnection fault,
When two of the discharge lamps 51 to 5n have a disconnection failure, the voltage comparison unit 402 outputs a high-level (logical value 1) signal S32.
Similarly, the voltage comparators 403 to 40n generate high-level (logical 1) signals S32 to S3n corresponding to the number of disconnections of the discharge lamps 51 to 5n. The signals S31 to S3n of the voltage comparison units 401 to 40n are
10 is input. The logic gate 410 shown is OR
A gate, and at least one of the signals S31 to S3n output from the voltage comparison units 401 to 40n is at a high level (logical value 1).
, A high-level (logical value 1) alarm signal S3 indicating that there is a disconnection is output.

Alternatively, a high-level signal may be generated when a disconnection failure occurs in a plurality r (<n) of the discharge lamps 51 to 5n. Also, the reference value S41
To S4n have the same value, and the value of the peak value signal S2 input to the voltage comparators 401 to 40n is
It may be changed every ~ 40n.

FIG. 5 is an electric circuit diagram showing a more specific circuit configuration of the discharge lamp lighting device according to the present invention. For the sake of simplicity, a specific example in which the number of discharge lamps is n = 2 will be described. The inverter unit 1 includes a DC / DC converter 11 and a control unit 1
2, a transformer T1, and an oscillating unit 13.

The DC / DC converter 11 is supplied with the DC input voltage Vin, operates according to the duty adjustment signal supplied from the duty adjustment unit 6, and outputs a square wave having a period τ.

The control section 12 controls the pulse width of the square wave output from the DC / DC converter based on the current detection signal S1 supplied from the output current detection circuit 2. By supplying a square wave with a controlled pulse width to the oscillating unit 13, the current Io flowing through the discharge lamps 51 and 52 is controlled,
The brightness of the discharge lamps 51 and 52 is kept constant.

The transformer T1 includes a primary winding N11, a secondary winding N12, and a feedback winding N13.

The oscillating unit 13 includes a primary winding N of the transformer T1.
11, the transformer T1 is part of the oscillation element,
The signal that is fed back to the input side through the feedback winding N13 of the transformer T1 continues the self-excited oscillation operation,
The AC voltage Vac generated in the secondary winding N12 is supplied to the output terminals To1 and To2.

The illustrated oscillating unit 13 is a well-known Loyer oscillating circuit. The emitters of the transistors Q12 and Q13 are commonly connected to ground, and the collector is connected to both ends of the primary winding N11 of the transformer T1. . The primary winding N11 of the transformer T1 has an intermediate tap, and the intermediate tap is guided to a power input line.

A capacitor C12 is connected between the collectors of the transistors Q12 and Q13. The bases of the transistors Q12 and Q13 are connected to the other ends of bias resistors R11 and R12 each having one end connected to a power input line. A feedback winding N1 is connected to two connection points between the bases of the transistors Q12 and Q13 and the resistors R11 and R12.
3 are connected at both ends. Therefore, transistor Q1
2. A positive feedback signal for continuing self-excited oscillation is supplied from the feedback winding N13 to the base of Q13.

The above-described lower oscillation circuit causes the secondary winding N12 of the transformer T1 to have a frequency of, for example, 50 kHz and 100 kHz.
An AC voltage Vac of 0 to 2000 Vrms is generated, and the high-frequency high-voltage AC voltage Vac is supplied to the discharge lamps 51 and 52.
And the discharge lamps 51 and 52 are turned on.

The output current detection circuit 2 includes two diodes D21 and D22. The diode D21 has an anode connected to one end of the secondary winding N12 of the transformer T1, and a cathode connected to the common terminal Tcom. The diode D22 has an anode connected to the cathode of the diode D21 and a cathode connected to one end of the resistor R21. The other end of the resistor R21 is an end that outputs the current detection signal S1. One end of the resistor R22 is connected to a connection point between the resistor R21 and the cathode of the diode D22. A capacitor C21 is connected between the other end of the resistor R21 that outputs the current detection signal S1 and the other end of the resistor R22. Resistors R21, R22 and capacitor C
21 configures an impedance adjustment circuit.

As seen from the output terminals To1 and To2, in the cycle in which the AC voltage Vac is positive, the diode D22
, The output current detector 2 outputs a half-wave current detection signal S1 (FIGS. 2B, 2E, and 3B).
(See (e)). In the cycle in which the AC voltage Vac is negative, the diode D21 conducts.

The peak value detector 3 includes a diode D31,
D32 and a capacitor C31. Half-wave current detection signal (voltage signal) output from the output current detection unit 2
S1 is subjected to a peak hold action by the capacitor C31 through the diode D31. Therefore, the DC peak value detection signal S2 is output from the terminal of the capacitor C31.

The alarm signal generator 4 includes a Zener diode D41, resistors R41 to R45, a capacitor C41, and a comparator IC41. Resistance R41, R42
Divides the peak value detection signal S2 having a constant voltage value through the Zener diode D41 at an appropriate resistance voltage division ratio, and divides the divided voltage by the (-) of the comparator IC41.
Supply to terminal.

The resistors R43 and R44 divide the constant voltage Vc1 supplied from the outside at an appropriate resistance voltage dividing ratio to generate a reference voltage. Then, the reference voltage is supplied to the comparator IC41.
(+) Terminal.

If no disconnection failure has occurred in any of the discharge lamps 51 and 52, the peak value detection signal S2 is output to the resistor R4
1. Comparator IC obtained by dividing voltage by R42
The divided voltage supplied to the (-) terminal of 41 is higher than the reference voltage supplied to the (+) terminal of the comparator IC4. At this time, the alarm signal S3 output from the comparator IC41 is at a low level (logical value 0).

Next, when a disconnection failure occurs in any of the discharge lamps 51 and 52, the divided voltage value supplied to the (-) terminal of the comparator IC 41 decreases.
The reference voltage supplied to the (+) terminal of C4 becomes higher than the divided voltage value supplied to the (-) terminal of the comparator IC41. Therefore, the alarm signal S3 output from the comparator IC41 becomes high level (logical value 1). Since the alarm signal S3 has become high level, the discharge lamps 51, 5
2 is determined to have a disconnection failure. FIG.
Is different from the illustration in FIG.
May be supplied to the (+) terminal and the divided voltage may be supplied to the (-) terminal. In this case, the logic of the alarm signal S3 is reversed.

Although illustration is omitted, when the number of discharge lamps becomes n, the alarm signal generator 4 has a circuit configuration according to the teaching of FIG.

[0062]

As described above, according to the present invention, the following effects can be obtained. (A) It is possible to provide a discharge lamp lighting device capable of reliably detecting disconnection of a discharge lamp with a simple circuit configuration. (B) It is possible to provide a discharge lamp lighting device capable of reliably detecting disconnection of the discharge lamp without reducing the dimming variable width.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a discharge lamp lighting device according to the present invention.

FIG. 2 is a waveform diagram illustrating an operation when a discharge lamp disconnection failure does not occur in the discharge lamp lighting device illustrated in FIG. 1;

FIG. 3 is a waveform diagram illustrating an operation when a discharge lamp disconnection failure occurs in the discharge lamp lighting device illustrated in FIG. 1;

FIG. 4 is a circuit diagram showing a specific configuration example of an alarm signal generation unit when the number of discharge lamps is n.

FIG. 5 is an electric circuit diagram showing a more specific circuit configuration of the discharge lamp lighting device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inverter part 2 Output current detection part 3 Peak value detection part 4 Alarm signal generation part 51-5n Discharge lamp

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Ryuichi Kimura 1-13-1 Nihonbashi, Chuo-ku, Tokyo TDK Corporation (72) Inventor Masahiro Takahashi 1-13-1 Nihonbashi, Chuo-ku, Tokyo TDK Incorporated (72) Inventor Satoshi Yasuhara 1-13-1 Nihonbashi, Chuo-ku, Tokyo TDK Corporation F-term (reference) 3K072 AA19 AB02 EA07 EB07 GB01 3K098 CC40 EE32 FF04

Claims (1)

[Claims] 1. A discharge lamp lighting device including an inverter unit, a peak value detection unit, and an alarm signal generation unit, wherein the inverter unit is a circuit that converts a DC input voltage into an AC voltage and outputs the AC voltage. A plurality of output terminals, and the AC voltage is given as a waveform having one cycle as a sum of an ON time alternated at a predetermined frequency and a predetermined amplitude and an OFF time at which the amplitude becomes a low level. The peak value detection unit calculates a peak value of a total sum of currents flowing through a plurality of discharge lamps connected to each of the output terminals,
A discharge lamp lighting device that detects as a voltage value, wherein the alarm signal generation unit generates an alarm signal from a peak value detection signal supplied from the peak value detection unit.