JP2003059682A - Lighting device of discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device that can control the protection operation steadily by detecting an abnormality of a discharge lamp while it has relatively a simple circuit structure and a small number of components. SOLUTION: The load-abnormality identification circuit 37 monitors the output signal of a comparator CP12 of a judgement circuit 36 which is an abnormality-possibility judgement means, and when the output signal of the comparator CP12 is at L level, it judges the load as normal, however, when it is at H level it compares the light control level with the specified value and if the light control level is larger than specified, it recognizes as abnormal and stops the oscillator of an inverter-oscillation control circuit 31 by a protection control circuit 38. And if the light control level is smaller than specified, the load-abnormality identification circuit monitors the output signal of the comparator CP11, and when the output signal of the comparator CP11 is at L level, it judges the load as normal and when it is at H level, it judges as abnormal.

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 converting a DC voltage of a DC power supply into a high frequency voltage and supplying it to a resonance load circuit including a resonance circuit and a discharge lamp.

[0002]

2. Description of the Related Art As a discharge lamp lighting device of this type, for example, a device having a circuit configuration shown in FIG. 17 is known (for example, see Japanese Patent Laid-Open No. 2000-12269). The discharge lamp lighting device configured as shown in FIG. 17 performs voltage conversion by connecting a power supply circuit 2 composed of a step-up chopper circuit between the DC output terminals of a full-wave rectifier 1 composed of a diode bridge that full-wave rectifies the AC power supply Vs. By converting the DC output of the power supply circuit 2 into high frequency power by the inverter circuit 3, high frequency power is supplied to the resonant load circuit 4 including the two discharge lamps La1 and La2, and the discharge lamps La1 and La2 are supplied with high frequency power. It is configured to be turned on.

The power supply circuit 2 includes an inductor L2 and a MOSF.
A series circuit including a switching element Q3 made of ET is connected between the DC output terminals of the full-wave rectifier 1, and an anode is connected to a connection point between the inductor L2 and the switching element Q3, and a series circuit including a smoothing capacitor C1. Are connected in parallel to the switching element Q3. here,
The switching element Q3 has a frequency (for example, several tens kHz) sufficiently higher than the power supply frequency by the chopper control circuit 20.
Is turned on and off.

However, in the power supply circuit 2, when the switching element Q3 is turned on and off, the energy accumulated in the inductor L2 during the on period of the switching element Q3 is released through the diode D1 during the off period of the switching element Q3, and all the energy is discharged. The energy emitted from the inductor L2 is superimposed on the output of the wave rectifier 1, and the smoothing capacitor C
Since 1 is charged, the voltage across the smoothing capacitor C1 can be boosted above the output voltage of the full-wave rectifier 1.

An inverter circuit 3 for converting the DC output from the power supply circuit 2 into a power constitutes a half-bridge type inverter circuit, and a series circuit of two switching elements Q1 and Q2 composed of MOSFETs outputs the output of the power supply circuit 2. A current detection resistor R1 is provided between both ends of the smoothing capacitor C1 which is an end.
Connected via. Here, both switching elements Q
The inverter control circuit 30 'alternately turns on and off 1, Q2 at high frequency. As described above, the MOSFETs are used for the switching elements Q1 and Q2, and it is possible to flow a current in the opposite direction to that at the time of turning on through the body diodes D01 and D02 even at the time of turning off.

A resonant load circuit 4 is connected between both ends of one switching element Q2 of the two switching elements Q1 and Q2 constituting the inverter circuit 3 via the above-mentioned current detecting resistor R1. The resonance load circuit 4 is 2
Each discharge lamp L is provided with a balancer BR that stabilizes the outputs of the discharge lamps La1, La2 of the lamp, and through a series circuit of an inductor L1 for resonance and a capacitor C3 for DC cut.
Connect one of the power source side terminals of a1 and La2 to each discharge lamp L
The other of the power supply side terminals of a1 and La2 is the balancer B, respectively.
It is connected to the connection point between the current detecting resistor R1 and the full-wave rectifier 1 via the R windings n1 and n2. That is, the series circuits of the discharge lamps La1 and La2 and the windings n1 and n2 of the balancer BR are connected in parallel with each other. In addition, the connection point between the inductor L1 and the capacitor C3 and the current detection resistor R
A resonance capacitor C2 is connected between the connection point of 1 and the full-wave rectifier 1. That is, the resonance load circuit 4
Is an inductor L1, a capacitor C2, a discharge lamp La1,
Including La2, inductor L1 and capacitor C2
The resonance voltage is applied to the discharge lamps La1 and La2 by the resonance action with
Is configured to be applied to. The capacitor C
No. 3 is selected so that the capacitance is sufficiently large and does not contribute to resonance.

However, when the switching elements Q1 and Q2 are alternately turned on and off by the inverter control circuit 30 ', the inductor L1- is turned on when the switching element Q1 is turned on.
A current flows through a path passing through the condenser C3-discharge lamps La1 and La2, and when the switching element Q2 is turned on, the condenser C3 is used as a power source and the condenser C3-inductor L1.
-A current flows in a path that passes through the switching element Q2-the current detection resistor R1-the discharge lamps La1, La2-the capacitor C3. That is, high-frequency power can be supplied to the discharge lamps La1 and La2.

The inductor L1 is provided with four secondary windings n4, n5, n6 and n7.
Discharge lamps La1, La2 are provided between both ends of 4, 4, n5, n6, n7 via capacitors C4, C5, C6, C7, respectively.
Filaments are connected. That is, in the secondary windings n4, n5, n6, and n7 provided in the inductor L2, the terminals labeled a to h are the discharge lamps La1 and La.
2 means that each terminal is labeled with a to h.

The inverter control circuit 30 'is configured to discharge the discharge lamps La1, based on a dimming signal from the outside (for example, a dimmer).
The switching element Q is adjusted so that the optical output of La2 is adjusted.
At least one of the operating frequency (the on / off frequency of the switching elements Q1 and Q2) and the duty of the switching elements Q1 and Q2 is changed.
Switching element Q for turning on and off 2 alternately
An inverter oscillation control circuit 31 having an oscillator for setting timings for turning on and off Q1 and Q2, and an inverter oscillation control circuit for receiving a dimming signal from the outside to control the output according to the dimming level. And a dimming signal processing circuit (dimming control circuit) 32 that transmits the signal to the light source 31. Here, the output frequency and duty of the oscillator (that is, the operating frequency and duty of the switching elements Q1, Q2) are adjusted according to the dimming level.

Further, the above-mentioned discharge lamp lighting device is provided with a discharge lamp L.
A load abnormality detection circuit 33 that detects the end of life of a1 and La2 (a state in which electron emission substances of the filament are scattered and electrons are no longer emitted) as an abnormality, and a load abnormality detection circuit 3
An oscillation stop control circuit that outputs an oscillation stop signal for stopping the oscillation of the inverter circuit 3 and protecting the inverter circuit 3 to the inverter oscillation control circuit 31 when an abnormality of the discharge lamps La1 and La2 is detected by And 34. Here, the inverter oscillation control circuit 31 receives the oscillation stop signal from the oscillation stop control circuit 34,
By stopping the oscillation of the inverter circuit 3, stress is prevented from being applied to the switching elements Q1 and Q2.

By the way, the discharge lamp La of the resonance load circuit 4
The abnormal modes related to 1 and La2 include discharge lamp La.
1, the discharge lamps La1 and La2 are extinguished at the end of their life, and the resonance frequency of the resonance load circuit 4 becomes higher than the output frequency of the inverter circuit 3 (frequency of turning on / off the switching elements Q1 and Q2). Therefore, an abnormal mode (hereinafter, referred to as a first abnormal mode) in which a large peak current flows through the switching elements Q1 and Q2, or one of the two discharge lamps La1 and La2 reaches the end of its life, and the voltage is applied to the balancer BR. An abnormal mode that occurs (hereinafter referred to as the second abnormal mode), or an abnormal mode in which the lamp voltage of the discharge lamps La1 and La2 increases due to the end of life of the discharge lamps La1 and La2 (hereinafter referred to as the third abnormal mode) )and so on.

Therefore, the load abnormality detecting circuit 33 includes a first detecting circuit 33a for detecting the first abnormal mode, a second detecting circuit 33b for detecting the second abnormal mode, and the third abnormal mode. A third detection circuit 33c for detecting
It is provided with one OR circuit OR to which the outputs of the detection circuits 33a to 33c are input, and the output terminal of the OR circuit OR is connected to the oscillation stop control circuit 34 described above. Here, the output signals of the respective detection circuits 33a to 33c are configured to be L level when the abnormal mode is not detected and H level when the abnormal mode is detected,
The load abnormality detection circuit 33 sets the output signal of the OR circuit OR to the H level when any one of the first abnormality mode, the second abnormality mode, and the third abnormality mode occurs. The H-level signal output from the OR circuit OR becomes the above-mentioned oscillation stop signal.

The first detection circuit 33a includes a diode Da,
A resistor Ra1 and Ra2, a capacitor Ca, a first comparator CP1 and the like are provided, and a voltage across the current detecting resistor R1 connected in series with the switching element Q2 and a reference voltage Vre.
The first comparator CP1 is used to compare f1 with the first comparator CP1.
When a current having a large peak value flows in 1 and Q2, the voltage across the current detection resistor R1 becomes higher than the reference voltage Vref1 and the output signal of the first comparator CP1 becomes H level.

The second detection circuit 33b includes resistors Rb1 and Rb.
2, Rb, diode Db, capacitor Cb, second comparator CP2, etc., and the winding n2 of the balancer BR.
The potential at the connection point between the discharge lamp La2 and the resistors Rb1 and Rb2.
Voltage is divided by using the voltage across the resistor Rb2 and the reference voltage Vre
It is configured to compare f2 with the second comparator CP2, and when one of the two discharge lamps La1 and La2 reaches the end of its life and the voltage of the balancer BR increases, the resistance Rb2 The voltage between both ends becomes higher than the reference voltage Vref2, and the output signal of the second comparator CP2 becomes H level.
Become a level.

The third detection circuit 33c includes resistors Rc1 and Rc.
2, Rc3, a diode Dc, a capacitor Cc, a third comparator CP3, and the like, and the potential at the connection point between the capacitor C3 and the discharge lamps La1 and La2 is set to the resistances Rc1 and Rc2.
The voltage is divided by using the voltage across the resistor Rc2 and the reference voltage Vre
The third comparator CP3 is configured to compare f3 with the third comparator CP3. When the discharge lamps La1 and La2 reach the end of their lives and the lamp voltages of the discharge lamps La1 and La2 increase, the voltage across the resistor Rc2 is increased. Becomes larger than the reference voltage Vref3, and the output signal of the third comparator CP3 becomes H level.

In the conventional discharge lamp lighting device, the inverter control circuit 30 'adjusts the light output of the discharge lamps La1 and La2 by controlling the on / off of the switching elements Q1 and Q2 according to the dimming signal. However, it is possible to turn on the discharge lamps La1 and La2 in the full lighting mode (Full mode) and the discharge lamps La1 and La2 at the dimming level of the dimming lower limit (dimming level when the dimming is deepest). Since the output of the inverter circuit 3 fluctuates during the dimming lower limit lighting mode (Dim mode),
Since the output of the inverter circuit 3 varies depending on the dimming level, the lamp voltage Vla also varies depending on the dimming level. Now, assume that the lamp voltage Vla at the time of full lighting is V _F , the lamp voltage Vla at the dimming lower limit is V _D , and the lamp voltage Vla is under normal load (when the discharge lamps La1 and La2 are not at the end of their life). If the load fluctuates within the range shown on the left side of FIG.
The fluctuation range is as shown on the right side of 8, and the fluctuation range of the lamp voltage Vla when the load is normal and the fluctuation range of the lamp voltage Vla when the load is abnormal partially overlap. Here, the lamp voltage V _D at the dimming lower limit when the load is normal is V1, and the lamp voltage V _F at the time of full lighting when the load is abnormal.
Since V1 can be the same lamp voltage Vla between V1 and V2 when the load is normal and when the load is abnormal, the reference voltage Vref3 in the above-mentioned third detection circuit 33c is, for example, a voltage Vref31 slightly larger than V1. Then, it becomes possible to detect the end of life of the discharge lamps La1 and La2 when the dimming lower limit is reached, and the reference voltage Vref3 is set to, for example, V2.
If the voltage Vref32 is set to be slightly lower than that, it becomes possible to detect the end of life of the discharge lamps La1 and La2 at the time of full lighting. That is, when the end of life of the discharge lamps La1 and La2 is detected only by the third detection circuit 33c described above,
It is necessary to switch the reference voltage Vref3 between the full lighting mode of the discharge lamps La1 and La2 and the dimming lower limit lighting mode.
That is, it is necessary to appropriately switch the reference voltage Vref3 according to the dimming level.

Therefore, the load abnormality detection circuit 33 in the above-described conventional discharge lamp lighting device includes the third detection circuit 33c.
Besides, since the first detection circuit 33a and the second detection circuit 33b are provided, the reference voltage Vref3 of the third detection circuit 33c is provided.
Since it is possible to detect an abnormality such as the end of life of the discharge lamps La1 and La2 at all dimming levels without switching over, the protective operation of stopping the oscillation of the inverter circuit 3 at the end of life of the discharge lamps La1 and La2. Control will be performed reliably.

[0018]

However, in the above-described conventional discharge lamp lighting device, since it is necessary to provide the load abnormality detection circuit 33 with three types of detection circuits 33a to 33c, the number of components is large and the circuit configuration is complicated. However, there was a problem that the cost became high as it became.

When a plurality of types of discharge lamps having different lamp voltages (hereinafter, referred to as lamp A and lamp B for convenience of description) are used as compatible loads, for example, as shown in FIG. Voltage V during normal operation
Assuming that la is V4, the lamp voltage Vla in the abnormal state at the time of full lighting is V3, and the lamp voltage Vla in the normal state at the time of full lighting is higher than V3, the lamp at the time of abnormal state during the full lighting Since the voltage Vla is higher than that in the normal state, the lamp A becomes abnormal while the lamp B becomes normal when the lamp voltage Vla is between V3 and V4. Therefore, when a plurality of types of discharge lamps having different lamp voltages Vla are used as the adaptive load, a determination means for determining the type of the discharge lamp is provided, and the reference voltage Vref3 is switched according to the determination result by the determination means. However, there is a problem that the number of parts is large, the circuit configuration is complicated, and the cost is high.

The present invention has been made in view of the above circumstances, and an object thereof is to reliably protect a discharge lamp by detecting an abnormality thereof while having a relatively simple circuit structure and a relatively small number of parts. It is to provide a discharge lamp lighting device capable of controlling operation.

[0021]

In order to achieve the above object, the invention of claim 1 is an inverter circuit which outputs a high frequency voltage using a switching element which is connected to a DC power source and is turned on and off at a high frequency, and an inverter circuit. And a resonance load circuit to which a high frequency voltage output from an inverter circuit is applied, which has a resonance inductor, a resonance capacitor, and a discharge lamp that is a load. The circuit, an oscillator capable of adjusting the operating frequency and duty of the switching element, a dimming control means for transmitting to the oscillator a signal according to a dimming level instructed by an external dimming signal,
A dimming level identifying means for recognizing the dimming level, and an abnormality possibility determining means for determining whether or not there is a possibility of abnormality in the discharge lamp,
The load abnormality identifying means for detecting the abnormality of the discharge lamp by combining the comparison result of the dimming level recognized by the dimming level identifying means with the specified value and the determination result by the abnormality possibility determining means, and the load abnormality identifying means release the abnormality. It is characterized by having a protection control means for controlling the operation of the oscillator so that the inverter circuit is protected when an abnormality of the electric light is detected. The load abnormality identification means recognizes the dimming level identification means. Since the abnormality of the discharge lamp is detected by combining the comparison result between the adjusted dimming level and the specified value and the determination result by the abnormality possibility determination means, it is not necessary to provide three detection circuits as in the conventional case, and it is relatively simple. Even though the number of parts is relatively small with a simple circuit configuration, it is possible to detect abnormalities in the discharge lamp at all dimming levels of the discharge lamp and reliably control the protection operation. That.

According to a second aspect of the present invention, an inverter circuit that outputs a high frequency voltage using a switching element that is connected to a DC power supply and that is turned on and off at a high frequency, a control circuit that turns on and off the switching element provided in the inverter circuit, and a resonance circuit are provided. And a resonance load circuit to which a high-frequency voltage output from an inverter circuit is applied, which has a capacitor for resonance and a discharge lamp that is a load, and a discharge lamp lighting device that uses a plurality of types of discharge lamps as compatible loads. There is a load identifying means for identifying the type of the discharge lamp, an abnormality possibility determining means for determining whether there is a possibility of abnormality in the discharge lamp, an identification result by the load identifying means and a determination result by the abnormality possibility determining means. Load abnormality detecting means for detecting the abnormality of the discharge lamp, and the inverter detecting the abnormality of the discharge lamp by the load abnormality detecting means. It is characterized by having a protection control means for controlling the operation of the oscillator so that the path is protected, and in the load abnormality identifying means, the identification result by the load identifying means and the identification result by the abnormality possibility determining means Since the abnormality of the discharge lamp is detected by combining the above, the number of parts is relatively small with a relatively simple circuit configuration, but the abnormality of the discharge lamp is detected regardless of the type of the discharge lamp, and the protection operation is reliably controlled. It can be performed.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the abnormality possibility determining means may determine the abnormality of the discharge lamp based on a change in voltage applied to the discharge lamp. Since the presence or absence of the discharge lamp is determined, it is possible to determine the presence or absence of the abnormality of the discharge lamp by detecting only the voltage applied to the discharge lamp.

According to a fourth aspect of the present invention, in the first or second aspect of the invention, the abnormality possibility determining means determines whether there is a possibility of abnormality of the discharge lamp based on a change in current flowing through the discharge lamp. Therefore, it is possible to determine whether there is a possibility of abnormality of the discharge lamp by detecting only the current flowing through the discharge lamp.

According to a fifth aspect of the present invention, in the first or second aspect of the invention, the abnormality possibility determining means determines whether or not there is a possibility of abnormality of the discharge lamp based on a change in light output of the discharge lamp. Therefore, it is possible to determine whether or not there is a possibility of abnormality of the discharge lamp by detecting only the light output of the discharge lamp.

According to a sixth aspect of the present invention, in the first or second aspect of the present invention, the abnormality possibility determining means may determine the abnormality of the discharge lamp based on a change in temperature of the discharge lamp or a circuit component. Since the presence or absence of the discharge lamp is determined, it is possible to determine whether or not there is a possibility of abnormality of the discharge lamp by detecting only the temperature change of the discharge lamp or the circuit component.

According to a seventh aspect of the present invention, in the first to sixth aspects of the present invention, the abnormality possibility determining means includes two comparators having different reference values for detecting the change, and the load abnormality. Since the identifying means selects one of the outputs of the two comparators and uses it as the determination result of the abnormality possibility determining means, the circuit configuration of the abnormality possibility determining means can be simplified.

According to an eighth aspect of the present invention, in the first aspect of the present invention, the dimming signal is a PWM signal in which the duty of a rectangular wave changes according to the dimming level, and the dimming level identifying means is the PWM signal. Since the dimming level is identified based on the duty of the dimming signal, the dimming level identifying means can easily identify the dimming level regardless of the state of the discharge lamp.

According to a ninth aspect of the present invention, in the first aspect of the present invention, the dimming signal is a PWM signal in which the duty of the rectangular wave changes according to the dimming level, and the dimming level identifying means is the PWM signal. Since the dimming level is identified based on the voltage level obtained by smoothing the dimming signal into a DC voltage, the dimming level identifying means can easily identify the dimming level regardless of the state of the discharge lamp.

According to a tenth aspect of the present invention, in the first aspect of the present invention, the dimming signal is a DC voltage signal whose voltage level changes in accordance with the dimming level, and the dimming level identifying means is the dimming level identifying means. Since the dimming level is identified based on the voltage level of the optical signal, the dimming level identifying means can easily identify the dimming level regardless of the state of the discharge lamp.

According to the invention of claim 11, in the invention of claim 1, the dimming level identifying means identifies the dimming level based on the operating frequency of the switching element.
The dimming level identification means can easily recognize the dimming level regardless of the state of the discharge lamp.

According to a twelfth aspect of the present invention, in the first aspect of the present invention, the dimming level identifying means identifies the dimming level based on the duty of turning on and off the switching element. The dimming level can be easily recognized regardless of the state of the discharge lamp.

According to a thirteenth aspect of the present invention, in the first aspect of the present invention, the dimming level identifying means identifies the dimming level based on the resonance current flowing through the resonance load circuit.
The dimming level identifying means can easily recognize the dimming level.

According to a fourteenth aspect of the present invention, in the first aspect of the present invention, the dimming level identifying means identifies the dimming level based on the light output of the discharge lamp. The light level can be easily recognized.

According to a fifteenth aspect of the present invention, in the first aspect of the present invention, the dimming level identifying means identifies the dimming level based on the filament current of the discharge lamp. The light level can be easily recognized.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) As shown in FIGS. 1 and 2, the discharge lamp lighting device according to the present embodiment has a direct-current DC of a full-wave rectifier 1 including a diode bridge for full-wave rectifying an AC power supply Vs. By connecting a power supply circuit 2 composed of a step-up chopper circuit between output terminals to perform voltage conversion, and by converting the DC output of the power supply circuit 2 into high frequency power by an inverter circuit 3, two discharge lamps composed of fluorescent lamps. High-frequency power is supplied to the resonance load circuit 4 including La1 and La2, and each discharge lamp L
It is configured to light a1 and La2 at a high frequency. Since the basic configuration of the discharge lamp lighting device of the present embodiment is substantially the same as the conventional configuration shown in FIG. 17, the same components as those of the conventional configuration are designated by the same reference numerals and the description thereof will be appropriately omitted. Although not shown in FIG. 2, in the discharge lamp lighting device of the present embodiment, since the high frequency blocking filter FL is inserted between the AC power supply Vs and the full-wave rectifier 1, the AC power supply Vs is not provided. Can be made almost continuous (the input current flowing from the AC power supply Vs to the full-wave rectifier 1 flows in a high frequency), and the input current distortion is controlled to suppress the high frequency noise to the power supply line of the AC power supply Vs. The wraparound can be reduced.

The discharge lamp lighting device according to the present embodiment is different in the configuration of the inverter control circuit 30 from the conventional configuration described above. That is, the inverter control circuit 30 in the present embodiment uses the operating frequencies of the switching elements Q1 and Q2 so that the light outputs of the discharge lamps La1 and La2 are adjusted based on the dimming signal from the outside (for example, the dimmer). Inverter oscillation control that changes the (on / off frequency of the switching elements Q1 and Q2) and that includes an oscillator that sets the timing to turn on and off the switching elements Q1 and Q2 in order to alternately turn on and off both switching elements Q1 and Q2. The circuit 31 and the dimming signal from the outside are transmitted to the inverter oscillation control circuit 31 in order to control the output in response to the dimming signal from the outside (the dimming signal instructed by the dimming signal from the outside. A dimming signal processing circuit (dimming control circuit) for transmitting a signal corresponding to the level to the oscillator 3
2 and the end of life of the discharge lamps La1 and La2, which are loads, are detected as abnormal, and when the abnormality is detected, the inverter circuit 3
And a load abnormality detection protection control circuit 35 that performs a protection operation of outputting a protection signal (for example, an oscillation stop signal) for protecting (for example, stopping oscillation) to the inverter oscillation control circuit 31. Here, the dimming signal processing circuit 32 transmits a dimming signal to the load abnormality detection protection control circuit 35 in addition to the inverter oscillation control circuit 31, and the load abnormality detection protection circuit 35 discharges the discharge lamps La1 and L.
When there is a possibility of abnormality in a2, the presence or absence of abnormality in the discharge lamps La1 and La2 is detected based on the dimming level, and when the abnormality in the discharge lamps La1 and La2 is detected, the protection operation is performed. . In addition, the inverter oscillation control circuit 31
When a protection signal is input from the load abnormality detection protection circuit 35, the switching element Q is stopped by stopping the oscillation of the oscillator and stopping the oscillation of the inverter circuit 3, for example.
It is designed to prevent stress on Q1 and Q2.

By the way, as described in the conventional example, as the abnormal mode related to the discharge lamps La1 and La2 of the resonance load circuit 4, the discharge lamps La1 and La2 are extinguished at the end of life of the discharge lamps La1 and La2, and the inverter circuit is turned off. The first abnormality in which the resonant frequency of the resonant load circuit 4 is higher than the output frequency of 3 (the on / off frequency of the switching elements Q1 and Q2) and the current having a large peak value flows through the switching elements Q1 and Q2. Mode and two discharge lamps L
A second abnormal mode in which one of a1 and La2 is at the end of its life and a voltage is generated in the balancer BR, or the discharge lamps La1 and La2.
There is a third abnormality mode in which the lamp voltage of the discharge lamps La1 and La2 becomes high when the value 2 becomes the end of life.

On the other hand, the load abnormality detection protection circuit 35 in the discharge lamp lighting device according to the present embodiment divides the lamp voltage by the resistors R11 and R12 to generate the reference voltages Vref11 and Vref.
A determination circuit 36 as an abnormality possibility determination means for determining whether or not there is a possibility of abnormality in the discharge lamps La1 and La2 as compared with 12.
Then, the dimming signal is transmitted from the dimming signal processing circuit 32 and the discrimination result by the discriminating circuit 36 is input. Based on the dimming level according to the dimming signal and the discrimination result of the discriminating circuit 36, the discharge lamps La1, La2 are detected. Load abnormality identifying circuit 37 as a load abnormality identifying means for identifying the presence or absence of abnormality, and inverter oscillation control so that the inverter circuit 3 is protected when the load abnormality identifying circuit 37 detects an abnormality in the discharge lamps La1, La2. The circuit 31 includes a protection control circuit 38 as protection control means for controlling the operation of the oscillator. Here, the determination circuit 36 divides the potential at the connection point between the capacitor C3 and the discharge lamps La1 and La2 by using the resistors R11 and R12, and compares the voltage across the resistor R12 and the reference voltages (reference values) Vref11 and Vref12. CP11, CP
12 is configured for comparison. That is, the determination circuit 36 includes a series circuit of two resistors R11 and R12,
A resistor R13 having an anode connected to the connection point of the resistors R11 and R12 and connected between the cathode of the diode D12 and the ground, a capacitor C14 connected in parallel to the resistor R13, a cathode of the diode D12 and a capacitor C.
It is provided with two comparators CP11 and CP12 whose connection points with 14 are respectively connected to the non-inverting input terminals. The dimming signal supplied from the dimmer to the dimming signal processing circuit 32 is a pulse width modulation (PWM) signal in which the duty of the rectangular wave changes according to the dimming level, and the load abnormality identifying circuit 37 includes Since the dimming level identifying means for recognizing the dimming level based on the duty of the dimming signal (recognizing the dimming level according to the magnitude of the duty) is provided, the discharge lamps La1, La2 are provided in the dimming level identifying means.
The dimming level can be easily recognized regardless of the state.

The operation of the inverter control circuit 30 according to this embodiment will be described below with reference to FIGS. 3 and 4. In FIG. 4, the horizontal axis represents the duty of the dimming signal supplied to the dimming signal processing circuit 32, and the vertical axis represents the lamp voltage Vla. In FIG. 4, a represents the characteristics when the load is normal,
B shows the characteristics when the load is abnormal. Regarding the duty described above, in FIG. 4, l <n <
m, the larger the duty, the larger the voltage across the smoothing capacitor C1 and the larger the lamp voltage Vla (approaching the dimming state in the Dim mode), and the smaller the duty, the smaller the lamp voltage Vla (in the Full mode). Approaching full lighting).

Load abnormality identification circuit 37 at the time of normal lighting
Monitors (selects) the output signal of the comparator CP12 (S1), and when the output signal of the comparator CP12 is at the L level, the load abnormality identifying circuit 37 loads the load (discharge lamp La
1, La2) is determined to be normal, and normal lighting is maintained. On the other hand, when the output signal of the comparator CP12 is at the H level, the dimming level is compared with the specified value (the dimming level when the duty is n (%) in FIG. 4) (S
2) If the dimming level is higher than the specified value, the discharge lamps La1 and La2 are recognized as abnormal lighting at the end of their life (S3), and the protection control circuit 38 oscillates the oscillator of the inverter oscillation control circuit 31. The protection operation for stopping the operation is controlled (S4). On the other hand, when the dimming level is smaller than the specified value in S2, the output signal of the comparator CP11 is monitored (selected) (S5), and the comparator CP1
When the output signal of 1 is L level, the load abnormality identifying circuit 37 determines that the loads (discharge lamps La1, La2) are normal and maintains normal lighting. In S5, when the output signal of the comparator CP11 is H level, the discharge lamp La
1 and La2 are recognized as abnormal lighting at the end of life (S3), and the protection control circuit 38 controls the protection operation to stop the oscillation of the oscillator of the inverter oscillation control circuit 31 (S4).

In the discharge lamp lighting device according to the present embodiment, however, when the determination circuit 36 determines that there is a possibility of abnormality in the discharge lamps La1 and La2, the load abnormality determination circuit 37 causes the dimming level identification means to determine. Since the abnormality of the discharge lamps La1 and La2 is detected based on the recognized dimming level, that is, the load abnormality discriminating means combines the discrimination result by the dimming level discriminating means and the discrimination result by the abnormality possibility discriminating result with the load. Since it is necessary to detect only the lamp voltage Vla, it is not necessary to provide the three types of detection circuits 33a to 33c as in the conventional configuration shown in FIG. 17, and it is not necessary to switch the reference voltage. Therefore, even though the number of parts is relatively small with a relatively simple circuit configuration, the discharge lamps La1 and La2 can be operated at all dimming levels of the discharge lamps La1 and La2. The normal operation can be detected to reliably control the protection operation, the stress generated in the switching elements Q1 and Q2 at the end of the life of the discharge lamps La1 and La2 can be reduced, and the inverter control circuit 30 can be simplified and at low cost. Can be realized. In the present embodiment, the inverter control circuit 30 constitutes a control circuit.

(Second Embodiment) The configuration of the discharge lamp lighting device according to the present embodiment is the same as that of the first embodiment, and only the operation of the load abnormality detection protection circuit 35 is different. Therefore, the operation of the load abnormality detection protection circuit 35 is performed. Will be described with reference to FIG.

Load abnormality identification circuit 37 at the time of normal lighting
Monitors (selects) the output signal of the comparator CP11 (S11), and the output signal of the comparator CP11 is H.
When it is at the level, it is identified that the load (discharge lamps La1, La2) is abnormal (S12), and the protection operation for stopping the oscillation of the oscillator of the inverter oscillation control circuit 31 is controlled (S1).
3). On the other hand, when the output signal of the comparator CP11 is at the L level, the output signal of the comparator CP12 is monitored (selected) (S14), and when the output signal of the comparator CP12 is at the L level, the load abnormality identification circuit 37 is notified. Then, the load (discharge lamps La1, La2) is determined to be normal, and normal lighting is maintained. On the other hand, in S14, when the output signal of the comparator CP12 is at the H level, the dimming level is compared with the specified value (the dimming level when the duty is n (%) in FIG. 4) (S15), and the dimming level is adjusted. When the light level is higher than the specified value, it is recognized that the discharge lamps La1 and La2 are abnormally lit at the end of life (S12), and protection control for stopping the oscillation of the inverter oscillation control circuit 31 is performed (S13). On the other hand, when the dimming level is lower than the specified value, the load abnormality identifying circuit 37 loads the load (discharge lamp L
It is determined that a1, La2) are normal, and normal lighting is maintained.

Therefore, in the discharge lamp lighting device of this embodiment, the discharge lamp La is detected by the discrimination circuit 36 as in the first embodiment.
When it is determined that there is a possibility of abnormality in 1 and La2, the load abnormality identification circuit 37 detects an abnormality in the discharge lamps La1 and La2 based on the dimming level recognized by the dimming level identifying means. Since the load abnormality identification means detects the abnormality of the load by combining the identification result of the dimming level identification means and the determination result of the abnormality possibility determination result, it is sufficient to detect only the lamp voltage Vla.
As in the conventional configuration shown in FIG.
Since it is not necessary to provide 33c and it is not necessary to switch the reference voltage, the discharge lamps La1 and La2 can be used at all the dimming levels of the discharge lamps La1 and La2 while the number of components is relatively small with a relatively simple circuit configuration. It is possible to detect the abnormality of the discharge lamp La and reliably control the protection operation.
It is possible to reduce the stress generated in the switching elements Q1 and Q2 at the end of life of the inverters 1 and La2, and to simplify and reduce the cost of the inverter control circuit 30.

By the way, in the first and second embodiments, the dimming signal input from the dimmer to the dimming signal processing circuit 32 is converted to PW.
As the M signal, the load abnormality identifying circuit 37 determines the dimming level based on the duty of the dimming signal (the dimming level is determined based on the magnitude of the duty). Electric lights La1 and La2
Although the dimming level can be easily recognized regardless of the state of, the dimming level identification means identifies the dimming level based on the voltage level obtained by smoothing the dimming signal into a DC voltage (the magnitude of the voltage level is large). Distinguishing the dimming level
You may do it. Also, as a dimming signal from the outside, P
Instead of the WM signal, a DC voltage signal whose voltage level changes according to the dimming level may be used. In this case, the dimming level identifying means identifies the dimming level based on the voltage level of the dimming signal. (The dimming level is identified by the magnitude of the voltage level).

(Embodiment 3) The basic configuration of the discharge lamp lighting device of the present embodiment is substantially the same as that of the first embodiment, and as shown in FIG. 6, two discharge lamps La1 and La2 are connected in series, The difference is that a resistor R21, which is a lamp current detection impedance element, is connected in series to a series circuit of two discharge lamps La1 and La2. The same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.
Further, in this embodiment, the power supply circuit 2 is represented by a battery symbol, and the chopper control circuit is not shown.

In the present embodiment, the discrimination circuit 36 as the abnormality possibility determination means for determining whether or not there is a possibility of abnormality in the discharge lamps La1 and La2 has the both ends of the resistor R21 which changes according to the magnitude of the lamp current Ila. Voltage and reference voltage (reference value) V
The comparators CP11 and CP12 are configured to compare ref11 and Vref12. That is, the determination circuit 3
Reference numeral 6 denotes a diode D13 whose anode is connected to a connection point between the discharge lamp La2 and the resistor R21, and a resistor R13 connected between the cathode of the diode D13 and the ground.
It comprises a capacitor C14 connected in parallel with the resistor R13, and two comparators CP11, CP12 whose connection points between the cathode of the diode D13 and the capacitor C14 are respectively connected to the non-inverting input terminal.

Further, in this embodiment, the inverter circuit 3
Is performed by changing the operating frequency (that is, the on / off frequency of the switching elements Q1 and Q2), and the load abnormality identification circuit 37 controls the dimming based on the operating frequency of the oscillator of the inverter oscillation control circuit 31. It is designed to recognize levels.

By the way, since the operating frequency of the switching elements Q1 and Q2 increases as the dimming is performed after all lighting, the lamp current Ila decreases as the dimming is performed.
Therefore, when the operating frequency of the oscillator which changes according to the dimming level is plotted on the horizontal axis and the lamp current Ila is plotted on the vertical axis as shown in FIG. 7, when the load is normal (when the discharge lamps La1 and La2 are not at the end of their life). The lamp current Ila becomes smaller as the operating frequency becomes higher as shown in (a) of the figure, and the lamp current Ila at the time of load abnormality (when the discharge lamps La1, La2 are at the end of their life) is as shown in (b) of the figure. It becomes smaller as the operating frequency becomes higher. In short, the discharge lamps La1, La
Since the lamp current Ila is smaller than that in the normal state at the time of an abnormality such as the end of life in FIG. 2, the lamp current in the normal state becomes larger than the lamp current in the abnormal state at the same dimming level at all the dimming levels. Therefore, in the present embodiment, the lamp current Ila = Iref1 when the load is normal and the operating frequency is the highest frequency (the operating frequency in the dimming lower limit mode).
The lamp current Ila = Ire when the reference voltage Vref11 is a value obtained by multiplying the resistance value of the resistor R21 with the reference voltage, and the operating frequency is the lowest frequency (the operating frequency in the all-lighting mode) due to a load abnormality.
The value obtained by multiplying the resistance value of the resistor R21 by f2 is the reference voltage Vref12.
There is. However, as shown in FIG. 7, when the lamp current Ila is between Iref1 and Iref2, the lamp current Ila alone cannot identify whether the load is normal or abnormal. Therefore, in the present embodiment, when performing the same control as that of FIG. 3 described in the first embodiment, m (kHz), which is the operating frequency when the lamp current Ila becomes Iref1 when the load is normal, and when the load is abnormal, N (kHz) between 1 (kHz), which is the operating frequency when the lamp current Ila becomes Iref2, is set as a prescribed value when the dimming level is determined.

Therefore, in the discharge lamp lighting device of the present embodiment, as in the first embodiment, the discharge lamp La is detected by the discrimination circuit 36.
When it is determined that there is a possibility of abnormality in 1 and La2, the load abnormality identification circuit 37 detects an abnormality in the discharge lamps La1 and La2 based on the dimming level recognized by the dimming level identifying means. Since the load abnormality discriminating means detects the abnormality of the load by combining the discrimination result by the dimming level discriminating means and the discrimination result by the abnormality possibility discrimination result, the lamp current Ila (that is, the voltage across the resistor R21).
Since it is only necessary to detect only three types of detection circuits 33a to 33c unlike the conventional configuration shown in FIG. 17 and it is not necessary to switch the reference voltage, it is possible to use a relatively simple circuit configuration. Although the score is relatively small,
It is possible to detect abnormalities in the discharge lamps La1 and La2 at all dimming levels of the discharge lamps La1 and La2 and reliably control the protective operation, and to switch the switching elements Q1 and Q2 at the end of the life of the discharge lamps La1 and La2. The generated stress can be reduced, and the inverter control circuit 30 can be simplified and reduced in cost.

In this embodiment, the load abnormality identifying circuit 3
The dimming level identification means 7 discriminates the dimming level based on the operating frequency of the oscillator (discriminates the dimming level based on the operating frequency of the oscillator), but based on the duty of the switching elements Q1 and Q2. The dimming level may be determined (the dimming level is determined based on the magnitude of the duty of the switching elements Q1 and Q2).

(Embodiment 4) The discharge lamp lighting device according to the present embodiment has substantially the same basic configuration as that of the first embodiment, and as shown in FIG. 8, two discharge lamps La1 and La2 are connected in series. In addition, a preheating circuit that causes a preheating current to flow to each filament of the discharge lamps La1 and La2 through a preheating transformer T1 described later using a voltage generated in the auxiliary winding n1a of the resonance inductor L1 as a power source, preheating Transformer T1 2
A preheating current detection circuit 39 that detects a preheating current through the next winding n24 to identify the dimming level is provided, and a temperature-sensitive element (not shown) disposed in proximity to the heat-generating component (for example, the switching element Q1) ( For example, a component temperature detection circuit 4 that detects the temperature of a heat-generating component (circuit component) with a thermistor.
The difference is that 0 is provided, and the load abnormality identification circuit 37
Is the output of the preheating current detection circuit 39 and the component temperature detection circuit 40.
It is characterized in that the load abnormality is identified based on the output of. Here, the above-mentioned preheating circuit is
A closed circuit composed of an auxiliary winding n1a of the inductor L1, an inductor L2, a primary winding n11 of the preheating transformer T1 and a capacitor C4 is provided, and the secondary windings n21, n22 and n23 of the preheating transformer T1 are the discharge lamp La1. , La2 filaments. That is, in the secondary windings n21, n22, and n23 provided in the preheating transformer T1, the terminals denoted by the symbols a to f are the discharge lamps La1 and La2.
It means that each terminal is connected to each of the terminals labeled a to f. The same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. Also,
In this embodiment, the power supply circuit 2 is represented by a battery symbol,
Illustration of the chopper control circuit is omitted.

By the way, the preheating current changes according to the fluctuation of the operating frequency of the inverter circuit 3, and the preheating current increases as the dimming is performed from the full lighting. Therefore, in the present embodiment,
The above-described preheating current detection circuit 39 is provided, and the load abnormality identification circuit 37 uses the dimming level input from the preheating current detection circuit 39 and the detected temperature input from the component temperature detection circuit 40 to discharge the discharge lamp La1, which is a load. An abnormality in La2 is detected.

Here, as shown in FIG. 9, when the horizontal axis represents the preheating current and the vertical axis represents the component temperature detected by the temperature sensing element, the component temperature when the load is normal is the preheating current as shown in FIG. It becomes smaller as it becomes larger, and the component temperature at the time of load abnormality becomes smaller as the preheating current becomes larger, as shown in B in the figure. In short, when the discharge lamps La1 and La2 are in an abnormal state such as at the end of their life, the component temperature is higher than that in the normal state. Therefore, at the same dimming level at all dimming levels, the abnormal component temperature is higher than the normal component temperature. Will also be higher.

Therefore, in the present embodiment, the component temperature is Tref1 when the load is normal and the preheating current is the full mode preheating current, and the preheating current is Dim when the load is abnormal.
The component temperature when the mode preheating current is set is Tref2. However, as shown in FIG. 9, the component temperature is Tre
When it is between f1 and Tref2, it is not possible to distinguish whether the discharge lamps La1 and La2 as loads are normal or abnormal only by the component temperature. Therefore, in the present embodiment, when performing the same control as that of FIG. 3 described in the first embodiment, the preheating current when the component temperature becomes Tref2 when the load is normal is 1 (A), and the component temperature when the load is abnormal is Set n (A) between l (A) and m (A) when the preheating current when Tref1 is m (A) as the specified value when determining the dimming level. is there. In the present embodiment, the component temperature detection circuit 40 uses the discharge lamp La.
1, La2 constitutes an abnormality possibility determining means for determining whether there is a possibility of abnormality, the preheating current detection circuit 39 constitutes a dimming level identifying means for recognizing a dimming level, and the load abnormality identifying circuit 37 , Which constitutes load abnormality identifying means. Here, the load abnormality identifying circuit 37 is provided with a dimming level identifying means for recognizing the dimming level based on the preheating current (recognizing the dimming level based on the magnitude of the preheating current). May only be detected.

In the discharge lamp lighting device according to the present embodiment, however, the abnormality of the discharge lamps La1 and La2 is determined based on the dimming level recognized by the dimming level identifying means by the load abnormality identifying circuit 37, as in the first embodiment. , I.e.,
Since the load abnormality discriminating means detects the abnormality of the load by combining the discrimination result by the dimming level discriminating means and the discrimination result by the abnormality possibility discrimination result, three types of detection circuits 33a are provided as in the conventional configuration shown in FIG. Since it is not necessary to provide .about.33c and it is not necessary to switch the reference voltage, the number of parts can be relatively reduced with a relatively simple circuit configuration.
It is possible to detect abnormalities in the discharge lamps La1 and La2 at all dimming levels of the discharge lamps La1 and La2 and reliably control the protective operation, and to switch the switching elements Q1 and Q2 at the end of the life of the discharge lamps La1 and La2. The generated stress can be reduced, and the inverter control circuit 30 can be simplified and reduced in cost.

(Embodiment 5) The discharge lamp lighting device according to the present embodiment has substantially the same basic configuration as that of Embodiment 1, and as shown in FIG. 10, a winding of a balancer BR is provided at one end of an inductor L1 for resonance. The discharge lamps La1 and La2 are connected via n1 and n2 (that is, the windings n1 and n2 and the discharge lamp La).
1 and La2 are connected in parallel to each other in series, and a C-type preheating resonance lighting circuit is configured in which resonance capacitors C21 and C22 are connected between the non-power source side ends of the discharge lamps La1 and La2. (That is, capacitor C21,
C22 also functions as a preheating condenser) and the light output detection circuit 41 that detects the light output of the discharge lamps La1 and La2 by the illuminance sensor 42. The feature is that the load abnormality is identified based on the output of the optical signal processing circuit 32 and the output of the optical output detection circuit 41. The first embodiment
The same components as those of the above are denoted by the same reference numerals and the description thereof will be omitted. Further, in this embodiment, the power supply circuit 2 is represented by a battery symbol, and the chopper control circuit is not shown.

By the way, in the present embodiment, the dimming signal input from the dimmer to the dimming signal processing circuit 32 is a DC voltage signal whose voltage level changes according to the dimming level, and the dimming signal is changed from full lighting to dimming. As it goes, the voltage level of the DC voltage increases. Now, assuming that the horizontal axis shows the DC voltage (the voltage level of the voltage) which changes depending on the dimming level and the vertical axis shows the optical output, the optical output under normal load is the DC voltage as shown in B of the figure. Becomes smaller as becomes larger, and the optical output at the time of load abnormality becomes smaller as the above-mentioned DC voltage becomes larger as shown in B of the same figure. In short, the discharge lamps La1, La
In the case of an abnormality such as the end of life, the light output is lower than that in the normal state. Therefore, the light output in the abnormal state is lower than that in the normal state at the same dimming level at all the dimming levels.

In the present embodiment, the light output when the load is normal and the direct current voltage is the voltage of the dimming lower limit (Dim mode) is set to Ref2. When the load is abnormal, the direct current voltage is fully turned on (Full mode). The optical output when the voltage of
ef1. However, as shown in FIG. 11, when the light output is between Ref1 and Ref2, it is not possible to distinguish whether the discharge lamps La1 and La2 as loads are normal or abnormal by the light output alone.
Therefore, in the present embodiment, in performing the same control as that of FIG. 3 described in the first embodiment, the direct current voltage when the light output becomes Ref1 when the load is normal is m (V), and the light output when the load is abnormal. When the DC voltage when Ref becomes Ref2 is l (V), n (V) between m (V) and l (V) is set as the specified value for determining the dimming level. There is. In the present embodiment, the load abnormality identifying circuit 37 determines whether or not there is a possibility of abnormality in the discharge lamps La1 and La2, which are loads, based on the output of the light output detection circuit 41 (depending on the magnitude of the output). The possibility determining means, the dimming level identifying means for recognizing the dimming level based on the output of the dimming signal processing circuit 32, and the dimming level identifying means when the abnormality possibility determining means determines that there is a possibility of abnormality. Discharge lamps La1, La2 based on the dimming level identified by
Is provided with load abnormality identifying means for detecting the abnormality.

Therefore, in the discharge lamp lighting device of the present embodiment, as in the case of the first embodiment, the load abnormality identifying circuit 37 determines the abnormality of the discharge lamps La1 and La2 based on the dimming level recognized by the dimming level identifying means. , I.e.,
Since the load abnormality discriminating means detects the abnormality of the load by combining the discrimination result by the dimming level discriminating means and the discrimination result by the abnormality possibility discrimination result, three types of detection circuits 33a are provided as in the conventional configuration shown in FIG. Since it is not necessary to provide .about.33c and it is not necessary to switch the reference voltage, the number of parts can be relatively reduced with a relatively simple circuit configuration.
It is possible to detect abnormalities in the discharge lamps La1 and La2 at all dimming levels of the discharge lamps La1 and La2 and reliably control the protective operation, and to switch the switching elements Q1 and Q2 at the end of the life of the discharge lamps La1 and La2. The generated stress can be reduced, and the inverter control circuit 30 can be simplified and reduced in cost.

(Embodiment 6) The basic configuration of the discharge lamp lighting device of this embodiment is substantially the same as that of Embodiment 1, and as shown in FIGS. 12 and 13, two discharge lamps La1 and La2 are provided.
Are connected in series, and the discharge lamps La1 and L that are loads
Load discriminating circuit 4 as a load discriminating means for discriminating the type of a2.
3 is provided in the inverter control circuit 30, and the load abnormality discrimination circuit 37 discriminates the load abnormality based on the output of the discrimination circuit 36 which is the abnormality possibility discrimination means and the discrimination signal outputted from the load discrimination circuit 43. Is different. The same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. Further, in this embodiment, the power supply circuit 2 is represented by a battery symbol, and the chopper control circuit is not shown.

The operation of the load abnormality detection / protection circuit 35 in this embodiment will be described below with reference to FIGS. 14 and 15. Note that FIG. 15 shows a case in which a plurality of types of discharge lamps having different lamp voltages (hereinafter, referred to as lamp A and lamp B for convenience of description) are used as a compatible load when the lamps A and B are normal and when they are abnormal. The lamp voltage Vla is shown. In the present embodiment, the lamp voltage Vla of the lamp A in the normal state at the time of full lighting is V4, and the lamp voltage Vla of the lamp B in the abnormal state at the time of full lighting is V3. When the lamp voltage Vla is between V3 and V4, it is impossible to determine whether the discharge lamps La1 and La2 are at the end of their life in the lamp A or whether the discharge lamps La1 and La2 are in the lamp B and are normal.

Load abnormality identification circuit 37 at the time of normal lighting
Monitors (selects) the output signal of the comparator CP12 (S31), and the output signal of the comparator CP12 is L
When it is at the level, the load abnormality identifying circuit 37 determines that the load is normal and maintains normal lighting. On the other hand, when the output signal of the comparator CP12 is at the H level, the load discrimination circuit 43 discriminates the load (S32), and when the load discrimination circuit 43 discriminates the load to be the lamp A, it is abnormally lit. If it is recognized (S33), the protection operation for stopping the oscillation of the inverter oscillation circuit 31 is controlled (S3).
4). In S32, if the load identification circuit 43 determines that the load is the lamp B, the load abnormality identification circuit 3
Monitor output signal of comparator CP11 at 7 (select)
When the output signal of the comparator CP11 is L level, the load abnormality identifying circuit 37 determines that the load is normal and maintains normal lighting. In S35, when the output signal of the comparator CP11 is at the H level, it is recognized as abnormal lighting (S33), and the protection operation for stopping the oscillation of the inverter oscillation control circuit 31 is controlled (S34).

In the discharge lamp lighting device of this embodiment, however, the load abnormality identifying means detects the abnormality of the discharge lamp by combining the identification result by the load identifying means and the identification result by the abnormality possibility determining means. By detecting the lamp voltage Vla, the end of life can be detected for each load having a different lamp voltage, and since it is not necessary to switch the reference voltage, the circuit configuration is relatively simple and the number of parts is relatively small. The stress generated in the switching elements Q1 and Q2 at the end of the life of the discharge lamps La1 and La2 can be reduced, and the inverter control circuit 30 can be simplified and reduced in cost.

(Embodiment 7) The structure of the discharge lamp lighting device of this embodiment is the same as that of Embodiment 6, and only the operation of the load abnormality detection protection circuit 35 is different. Therefore, the operation of the load abnormality detection protection circuit 35 is This will be described with reference to FIG.

Load abnormality identification circuit 37 at the time of normal lighting
Monitors (selects) the output signal of the comparator CP11 (S41), and the output signal of the comparator CP11 is H.
When it is at the level, the load abnormality identification circuit 37 identifies that the load is abnormal (S42), and controls the protection operation for stopping the oscillation of the inverter oscillation control circuit 31 (S43). On the other hand, in S41, when the output signal of the comparator CP11 is at the L level, the output signal of the comparator CP12 is monitored (selected) (S44), and when the output signal of the comparator CP12 is at the L level, the load abnormality identification circuit 37 is notified. It is determined that the load is normal and the normal lighting is maintained. In S44, when the output signal of the comparator CP12 is at the H level, the load discrimination circuit 43 refers to the load discrimination (S45), and when the load discrimination circuit 43 discriminates the load to be the lamp A, the load abnormality discrimination circuit is displayed. In 37, the abnormal lighting is recognized (S42), and the protection operation for stopping the oscillation of the inverter oscillation circuit 31 is controlled (S42).
43). In S45, if the load identification circuit 43 determines that the load is the lamp B, the load abnormality identification circuit 3
In step 7, it is determined that the load is normal, and normal lighting is maintained.

Therefore, in the discharge lamp lighting device of the present embodiment, the load abnormality identifying means combines the identification result by the load identifying means and the identification result by the abnormality possibility determining means in the same manner as in the sixth embodiment. Since the abnormality is detected, by detecting the lamp voltage Vla, it is possible to detect the end of life of each load having a different lamp voltage.
Since it is not necessary to switch the reference voltage, the discharge lamp L can have a relatively simple circuit configuration and a relatively small number of parts.
Switching elements Q1 and Q2 at the end of life of a1 and La2
It is possible to reduce the stress generated in the inverter control circuit 30, and to simplify and reduce the cost of the inverter control circuit 30.

In the sixth and seventh embodiments, the same configuration as that of the first and second embodiments is adopted as the abnormality possibility determining means for determining the possibility of the abnormality of the discharge lamps La1 and La2 which are loads. The configuration similar to that of any of the third to fifth embodiments may be adopted.

[0070]

According to the invention of claim 1, an inverter circuit for outputting a high frequency voltage using a switching element which is connected to a DC power supply and is turned on and off at a high frequency, and a control circuit which turns on and off a switching element provided in the inverter circuit,
A resonance load circuit having a resonance inductor, a resonance capacitor, and a discharge lamp that is a load, to which a high-frequency voltage output from an inverter circuit is applied, and a control circuit adjusts the operating frequency and duty of a switching element. Possible oscillator, dimming control means for transmitting to the oscillator a signal according to the dimming level instructed by the dimming signal from the outside, dimming level identifying means for recognizing the dimming level, abnormality of the discharge lamp Of the discharge lamp abnormality by combining the abnormality possibility determination means for determining whether there is a possibility of a discharge, the comparison result of the dimming level recognized by the dimming level identification means with the specified value, and the determination result by the abnormality possibility determination means. The load abnormality detection means and the operation of the oscillator to protect the inverter circuit when the load abnormality detection means detects an abnormality in the discharge lamp The load abnormality discriminating means combines the result of comparison between the dimming level recognized by the dimming level discriminating means with a specified value and the discrimination result by the abnormality possibility discriminating means to discharge the discharge lamp. Since it is not necessary to provide three detection circuits as in the conventional case, the number of parts is relatively small with a relatively simple circuit configuration, and the discharge lamp can be detected at all dimming levels. There is an effect that an abnormality can be detected and the protection operation can be surely controlled.

According to a second aspect of the present invention, an inverter circuit for outputting a high frequency voltage by using a switching element connected to a DC power source and turned on and off at a high frequency, a control circuit for turning on and off a switching element provided in the inverter circuit, and a resonance circuit are provided. And a resonance load circuit to which a high-frequency voltage output from an inverter circuit is applied, which has a capacitor for resonance and a discharge lamp that is a load, and a discharge lamp lighting device that uses a plurality of types of discharge lamps as compatible loads. There is a load identifying means for identifying the type of the discharge lamp, an abnormality possibility determining means for determining whether there is a possibility of abnormality in the discharge lamp, an identification result by the load identifying means and a determination result by the abnormality possibility determining means. Load abnormality detecting means for detecting the abnormality of the discharge lamp, and the inverter detecting the abnormality of the discharge lamp by the load abnormality detecting means. And a protection control means for controlling the operation of the oscillator so that the path is protected, and the load abnormality identifying means combines the identification result by the load identifying means and the identification result by the abnormality possibility determining means with the discharge lamp. Since the abnormality is detected, it is possible to reliably control the protection operation by detecting the abnormality of the discharge lamp regardless of the type of the discharge lamp with a relatively simple circuit configuration and a relatively small number of parts. There is an effect.

According to a third aspect of the present invention, in the first or second aspect of the invention, the abnormality possibility determining means may determine the abnormality of the discharge lamp based on the change in the voltage applied to the discharge lamp. Since the presence or absence of the discharge lamp is determined, it is possible to determine whether or not there is a possibility of abnormality of the discharge lamp by detecting only the voltage applied to the discharge lamp.

According to a fourth aspect of the present invention, in the first or second aspect of the invention, the abnormality possibility determining means determines whether or not there is a possibility of abnormality of the discharge lamp based on a change in current flowing through the discharge lamp. Therefore, it is possible to determine whether or not there is a possibility of abnormality of the discharge lamp by detecting only the current flowing through the discharge lamp.

According to a fifth aspect of the present invention, in the first or second aspect of the invention, the abnormality possibility determining means determines whether there is a possibility of abnormality of the discharge lamp based on a change in light output of the discharge lamp. Therefore, it is possible to determine whether or not there is a possibility of abnormality of the discharge lamp by detecting only the light output of the discharge lamp.

According to a sixth aspect of the present invention, in the first or second aspect of the invention, the abnormality possibility determining means determines whether there is a possibility of abnormality of the discharge lamp based on a temperature change of the discharge lamp or a circuit component. Since the presence / absence of the discharge lamp is determined, it is possible to determine the presence / absence of the abnormality of the discharge lamp by detecting only the temperature change of the discharge lamp or the circuit component.

According to a seventh aspect of the present invention, in the first to sixth aspects of the present invention, the abnormality possibility determination means includes two comparators having different reference values for detecting the change, and the load abnormality. Since the identifying means selects one of the outputs of the two comparators and uses it as the determination result of the abnormality possibility determining means, there is an effect that the circuit configuration of the abnormality possibility determining means can be simplified.

According to an eighth aspect of the present invention, in the first aspect of the present invention, the dimming signal is a PWM signal in which the duty of a rectangular wave changes according to the dimming level, and the dimming level identifying means is the PWM signal. Since the dimming level is identified based on the duty of the dimming signal, there is an effect that the dimming level identifying means can easily recognize the dimming level regardless of the state of the discharge lamp.

According to a ninth aspect of the present invention, in the first aspect of the present invention, the dimming signal is a PWM signal in which the duty of a rectangular wave changes according to the dimming level, and the dimming level identifying means is the PWM signal. Since the dimming level is identified based on the voltage level obtained by smoothing the dimming signal into a DC voltage, the dimming level identifying means can easily identify the dimming level regardless of the state of the discharge lamp. There is.

According to a tenth aspect of the present invention, in the first aspect of the present invention, the dimming signal is a DC voltage signal whose voltage level changes according to the dimming level, and the dimming level identifying means is the dimming level identifying means. Since the dimming level is identified based on the voltage level of the optical signal, there is an effect that the dimming level identifying means can easily identify the dimming level regardless of the state of the discharge lamp.

According to the invention of claim 11, in the invention of claim 1, the dimming level identifying means identifies the dimming level based on the operating frequency of the switching element.
The dimming level identifying means can easily recognize the dimming level regardless of the state of the discharge lamp.

According to a twelfth aspect of the present invention, in the first aspect of the present invention, the dimming level identifying means identifies the dimming level based on the duty of turning on and off the switching element. The dimming level can be easily recognized regardless of the state of the discharge lamp.

According to a thirteenth aspect of the present invention, in the first aspect of the present invention, the dimming level identifying means identifies the dimming level based on the resonance current flowing through the resonance load circuit.
There is an effect that the dimming level identifying means can easily recognize the dimming level.

According to a fourteenth aspect of the present invention, in the first aspect of the present invention, the dimming level identifying means identifies the dimming level based on the light output of the discharge lamp. There is an effect that the light level can be easily recognized.

According to a fifteenth aspect of the present invention, in the first aspect of the present invention, the dimming level identifying means identifies the dimming level based on the filament current of the discharge lamp. There is an effect that the light level can be easily recognized.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment.

FIG. 2 is a schematic circuit block diagram of the above.

FIG. 3 is an operation explanatory diagram of the above.

FIG. 4 is an operation explanatory diagram of the above.

FIG. 5 is an operation explanatory diagram of the second embodiment.

FIG. 6 is a circuit diagram showing a third embodiment.

FIG. 7 is an operation explanatory diagram of the above.

FIG. 8 is a circuit diagram showing a fourth embodiment.

FIG. 9 is an explanatory diagram of an operation of the above.

FIG. 10 is a circuit diagram showing a fifth embodiment.

FIG. 11 is an operation explanatory diagram of the above.

FIG. 12 is a circuit diagram showing a sixth embodiment.

FIG. 13 is a schematic circuit block diagram of the above.

FIG. 14 is an explanatory diagram of an operation of the above.

FIG. 15 is an operation explanatory diagram of the above.

FIG. 16 is an operation explanatory diagram of the seventh embodiment.

FIG. 17 is a circuit diagram showing a conventional example.

FIG. 18 is an operation explanatory diagram of the above.

FIG. 19 is an operation explanatory diagram of the above.

[Explanation of symbols]

1 full-wave rectifier 2 power supply circuit 3 inverter circuit 4 resonant load circuit 20 Chopper control circuit 30 Inverter control circuit 31 Inverter oscillation control circuit 32 dimming signal processing circuit 35 Load abnormality detection protection control circuit 36 Discrimination circuit 37 Load abnormality identification circuit 38 Protection control circuit Vs AC power supply La1 discharge lamp La2 discharge lamp Q1 switching element Q2 switching element CP11 comparator CP12 comparator

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kiyoshi Ogasawara             1048, Kadoma, Kadoma-shi, Osaka Matsushita Electric Works Co., Ltd.             Inside the company F term (reference) 3K072 AA01 AB02 AC11 AC20 BA03                       BB01 BC01 EB05 GA02 GB12                       GC04 HA10                 3K098 CC07 CC17 CC23 CC41 DD20                       DD22 DD33 DD36 DD37 DD43                       EE27 EE32 FF07 FF08 FF14                       FF20 GG02                 5H007 AA05 AA12 BB03 BB11 CA02                       CB17 CB22 CC12 DA05 DC02                       EA09 FA03 FA13 GA08

Claims (15)

[Claims] 1. An inverter circuit that outputs a high-frequency voltage using a switching element that is connected to a DC power supply and that is turned on and off at a high frequency, a control circuit that turns on and off a switching element provided in the inverter circuit, an inductor for resonance, and a resonance element. A resonant load circuit to which a high frequency voltage output from an inverter circuit is applied, which has a discharge lamp that is a capacitor and a load, and a control circuit that controls an operating frequency and duty of a switching element and an external The dimming control means for transmitting a signal corresponding to the dimming level indicated by the dimming signal to the oscillator, the dimming level identifying means for recognizing the dimming level, and the presence / absence of the abnormality of the discharge lamp are determined. The abnormality possibility determination means, the comparison result between the dimming level recognized by the dimming level identification means and the specified value Controls the operation of the oscillator so as to protect the inverter circuit when the abnormality of the discharge lamp is detected by the load abnormality identifying means and the abnormality of the discharge lamp is detected by combining the determination results of the capability determining means. And a protection control means for controlling the discharge lamp lighting device. 2. An inverter circuit which outputs a high frequency voltage using a switching element which is connected to a DC power supply and which is turned on and off at a high frequency, a control circuit which turns on and off a switching element provided in the inverter circuit, an inductor for resonance and a resonance circuit. And a resonant load circuit to which a high-frequency voltage output from an inverter circuit is applied, which has a discharge lamp that is a capacitor and a load, and a discharge lamp lighting device that uses a plurality of types of discharge lamps as compatible loads. Load identifying means for identifying the type of the discharge lamp, abnormality possibility determining means for determining whether or not there is a possibility of abnormality in the discharge lamp, and the discharge result by combining the identification result by the load identifying means and the determination result by the abnormality possibility determining means. Load abnormality detecting means for detecting the abnormality of the discharge lamp and the inverter circuit is protected when the abnormality of the discharge lamp is detected by the load abnormality detecting means. And a protection control means for controlling the operation of the oscillator. 3. The abnormality possibility determining means determines whether or not there is a possibility of abnormality of the discharge lamp based on a change in voltage applied to the discharge lamp. 2. The discharge lamp lighting device according to 2. 4. The abnormality possibility determining means determines whether or not there is a possibility of abnormality in the discharge lamp based on a change in a current flowing through the discharge lamp. Discharge lamp lighting device. 5. The abnormality possibility determining means determines whether there is a possibility of abnormality of the discharge lamp based on a change in light output of the discharge lamp. Discharge lamp lighting device. 6. The abnormality possibility determining means determines whether or not there is a possibility of abnormality in the discharge lamp based on a change in temperature of the discharge lamp or a circuit component. 2. The discharge lamp lighting device according to 2. 7. The abnormality possibility determining means includes two comparators having different reference values for detecting the change, and the load abnormality determining means selects one from the outputs of the two comparators. The discharge lamp lighting device according to any one of claims 1 to 6, wherein the discharge lamp lighting device is used as a determination result of the abnormality possibility determining means. 8. The dimming signal is a PWM signal in which the duty of a rectangular wave changes according to the dimming level, and the dimming level identifying means determines the dimming level based on the duty of the dimming signal. The discharge lamp lighting device according to claim 1, wherein the discharge lamp lighting device is identified. 9. The dimming signal is a PWM signal in which the duty of a rectangular wave changes according to the dimming level, and the dimming level identifying means sets the dimming signal to a voltage level smoothed to a DC voltage. The discharge lamp lighting device according to claim 1, wherein the dimming level is identified based on the dimming level. 10. The dimming signal is a direct-current voltage signal whose voltage level changes according to the dimming level, and the dimming level identifying means determines the dimming level based on the voltage level of the dimming signal. The discharge lamp lighting device according to claim 1, wherein the discharge lamp lighting device is identified. 11. The discharge lamp lighting device according to claim 1, wherein the dimming level identifying means identifies the dimming level based on an operating frequency of the switching element. 12. The discharge lamp lighting device according to claim 1, wherein the dimming level identifying means identifies the dimming level based on an on / off duty of the switching element. 13. The discharge lamp lighting device according to claim 1, wherein the dimming level identifying means identifies the dimming level based on a resonance current flowing through the resonance load circuit. 14. The discharge lamp lighting device according to claim 1, wherein the dimming level identification means identifies the dimming level based on the light output of the discharge lamp. 15. The discharge lamp lighting device according to claim 1, wherein the dimming level identifying means identifies the dimming level based on a filament current of the discharge lamp.