JP2008186615A - Discharge lamp lighting device, and emergency lighting fixture - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely detect abnormal discharge due to connection failure of an inverter circuit output part, without causing malfunction due to disturbance such as external noise. <P>SOLUTION: The discharge lamp lighting device equipped with an inverter circuit for lighting a discharge lamp to be a light source by converting a direct-current voltage into a high-frequency alternating current voltage is provided with an abnormal discharge detecting means detecting electric characteristics of an output part or an input part of the inverter circuit and detecting a difference in electric characteristics between a normal lighting time of the discharge lamp and an abnormal discharge generation time due to incomplete connection of the inverter circuit output part. The abnormal discharge detecting means either detects a voltage or a consumption power at an output end of the inverter circuit, or detects a voltage of an element connected in series with the discharge lamp and limiting a current flowing in the discharge lamp. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a discharge lamp lighting device for lighting a discharge lamp by converting a DC power source into a high-frequency AC voltage, and an emergency lighting fixture such as a guide lamp fixture equipped with the discharge lamp lighting device.

  Conventionally, as this type of discharge lamp lighting device, for example, a device that lights a cold cathode discharge lamp using an L-push-pull inverter connected to a DC power source is used. In this device, the resonant voltage of self-excited oscillation is boosted according to the turns ratio of the transformer, output to the secondary side, and connected to the discharge lamp via a current limiting ballast capacitor. Dimming of the discharge lamp is performed by adjusting the voltage of the DC power source or intermittently cutting off the voltage supply from the DC power source to the inverter at several tens to several hundreds of Hz.

  Such a discharge lamp lighting device is generally provided with a protection circuit that stops the oscillation operation of the inverter when the discharge lamp is disconnected. For example, the current flowing through the discharge lamp is constantly monitored, and when the current interruption is detected, the protection circuit stops the operation of the inverter. However, since a high voltage is applied to a connector or the like for connecting the discharge lamp, if a connection failure or the like of the discharge lamp occurs, the protection circuit may not work depending on the connection state. This is because, when the distance of the location where the conduction of the connecting portion is interrupted is small, abnormal discharge such as spark discharge or glow discharge occurs, and the current to the discharge lamp continues to flow.

  As a technique for solving such a problem, for example, Japanese Patent No. 3123161 and Japanese Patent Application Laid-Open No. 2002-151287 are known. Specifically, the former shuts off the power supply to the inverter when the frequency component of the discharge pulse generated on the secondary side of the transformer is detected during abnormal discharge, and the latter has a current detector higher than the oscillation frequency of the inverter The abnormal discharge is stopped by stopping the voltage supply to the discharge lamp when the discharge noise frequency component is detected.

Japanese Patent No. 3655295 discloses a method for detecting the occurrence of abnormal discharge by detecting a magnetic flux change caused by a change in circuit current during abnormal discharge and stopping the abnormal discharge.
Japanese Patent No. 3123161 JP 2002-151287 A Japanese Patent No. 3655295

  However, these known techniques (Japanese Patent No. 3123161, Japanese Patent Laid-Open No. 2002-151287) all have components higher in frequency than the oscillation frequency of the inverter, such as “discharge pulse” and “discharge noise” generated by abnormal discharge. It is characterized by detecting. Therefore, there is a risk that malfunctions may occur due to, for example, external noise other than when a connection failure occurs due to the discharge lamp being disconnected. In this case, even in a normal lighting state in which abnormal discharge due to poor connection does not occur, the protection circuit operates and the discharge lamp is turned off. Japanese Patent No. 3655295 discloses a method of detecting a magnetic flux change by winding a current detection winding around a core or circuit wiring. However, this method may lead to complicated manufacturing.

  The present invention has been made in view of the above points, and in a discharge lamp lighting device used for an emergency lighting apparatus or the like, poor connection of an inverter circuit output unit without causing malfunction due to disturbance such as external noise. It is an object of the present invention to reliably detect abnormal discharge due to the above.

  In order to solve the above problems, the invention of claim 1 is a discharge lamp lighting device comprising an inverter circuit for lighting a discharge lamp as a light source by converting a DC voltage into a high-frequency AC voltage as shown in FIG. An abnormal discharge detecting means for detecting an electric characteristic of an output part or an input part of the inverter circuit and detecting a difference in electric characteristic between when the discharge lamp is normally lit and when an abnormal discharge occurs due to incomplete connection of the inverter circuit output part The abnormal discharge detecting means detects the voltage at the output terminal of the inverter circuit.

  The invention of claim 2 is a discharge lamp lighting device comprising an inverter circuit for lighting a discharge lamp as a light source by converting a DC voltage into a high frequency AC voltage, and detecting an electrical characteristic of an output part or an input part of the inverter circuit, The abnormal discharge detecting means includes an abnormal discharge detecting means for detecting a difference in electrical characteristics between when the discharge lamp is normally lit and when abnormal discharge occurs due to incomplete connection of the inverter circuit output unit, as shown in FIG. The voltage of an element connected in series with the discharge lamp and limiting the current flowing through the discharge lamp is detected.

  The invention of claim 3 is a discharge lamp lighting device comprising an inverter circuit for lighting a discharge lamp as a light source by converting a DC voltage into a high frequency AC voltage, and detecting an electrical characteristic of an output part or an input part of the inverter circuit, The abnormal discharge detecting means includes an abnormal discharge detecting means for detecting a difference in electrical characteristics between when the discharge lamp is normally lit and when abnormal discharge occurs due to incomplete connection of the inverter circuit output unit, as shown in FIG. The power consumption of the output terminal of the inverter circuit is detected.

  The invention of claim 4 is a discharge lamp lighting device comprising an inverter circuit for lighting a discharge lamp as a light source by converting a DC voltage into a high frequency AC voltage, and detecting an electrical characteristic of an output part or an input part of the inverter circuit, The abnormal discharge detecting means includes an abnormal discharge detecting means for detecting a difference in electrical characteristics between when the discharge lamp is normally lit and when abnormal discharge occurs due to incomplete connection of the inverter circuit output unit, as shown in FIG. The impedance of the discharge lamp is calculated and detected from the voltage at the output terminal of the inverter circuit and the current flowing through the discharge lamp.

  The invention of claim 5 is a discharge lamp lighting device comprising an inverter circuit for lighting a discharge lamp as a light source by converting a DC voltage into a high frequency AC voltage, and detecting an electrical characteristic of an output part or an input part of the inverter circuit, An abnormal discharge detecting means for detecting a difference in electrical characteristics between when the discharge lamp is normally lit and when an abnormal discharge occurs due to incomplete connection of the inverter circuit output unit, as shown in FIG. The voltage detected at the output terminal of the inverter circuit is compared with the current flowing through the discharge lamp for detection.

  The invention of claim 6 is a discharge lamp lighting device comprising an inverter circuit for lighting a discharge lamp as a light source by converting a DC voltage into a high frequency AC voltage, and detecting an electrical characteristic of an output part or an input part of the inverter circuit, An abnormal discharge detecting means for detecting a difference in electrical characteristics between when the discharge lamp is normally lit and when an abnormal discharge occurs due to incomplete connection of the inverter circuit output unit, as shown in FIG. Detecting the input power to the inverter circuit from the DC voltage.

  The invention of claim 7 is a discharge lamp lighting device comprising an inverter circuit for lighting a discharge lamp as a light source by converting a DC voltage into a high frequency AC voltage, and detecting an electrical characteristic of an output part or an input part of the inverter circuit, And an abnormal discharge detecting means for detecting a difference in electrical characteristics between when the discharge lamp is normally lit and when an abnormal discharge occurs due to incomplete connection of the inverter circuit output unit. As shown, the oscillation frequency of the inverter circuit is detected.

  The invention of claim 8 is a discharge lamp lighting device comprising an inverter circuit for lighting a discharge lamp as a light source by converting a DC voltage into a high frequency AC voltage, and detecting an electrical characteristic of an output part or an input part of the inverter circuit, An abnormal discharge detecting means for detecting a difference in electrical characteristics between when the discharge lamp is normally lit and when an abnormal discharge occurs due to incomplete connection of the inverter circuit output unit, the abnormal discharge detecting means as shown in FIG. The current flowing through the discharge lamp and the input current from the DC voltage to the inverter circuit are compared and detected.

  The invention according to claim 9 includes an inverter circuit that turns on a discharge lamp as a light source by converting a DC voltage into a high-frequency AC voltage, detects an electrical characteristic of an output part or an input part of the inverter circuit, and normalizes the discharge lamp. In the discharge lamp lighting device comprising an abnormal discharge detecting means for detecting a difference in electrical characteristics between when the lamp is turned on and when an abnormal discharge occurs due to incomplete connection of the inverter circuit output unit, the abnormal discharge detecting means is shown in FIGS. As shown in FIG. 28, a mask is provided so as not to detect until the electrical characteristics of the discharge lamp are substantially stabilized at the start of lighting of the discharge lamp.

  The invention of claim 10 includes an inverter circuit that turns on a discharge lamp as a light source by converting a DC voltage into a high-frequency AC voltage, detects an electrical characteristic of an output part or an input part of the inverter circuit, and normalizes the discharge lamp. In a discharge lamp lighting device having an abnormal discharge detecting means for detecting a difference in electrical characteristics between when the lamp is lit and when an abnormal discharge occurs due to incomplete connection of the inverter circuit output section, as shown in FIGS. It is characterized by detecting that the electric lamp has been started and outputting a false detection prevention signal V4 in synchronization with the detection signal.

  The invention of claim 11 includes an inverter circuit that turns on a discharge lamp as a light source by converting a DC voltage into a high-frequency AC voltage, detects an electrical characteristic of an output part or an input part of the inverter circuit, and normalizes the discharge lamp. In a discharge lamp lighting device comprising an abnormal discharge detection means for detecting a difference in electrical characteristics between when the lamp is lit and when an abnormal discharge occurs due to incomplete connection of the inverter circuit output section, as shown in FIG. The operation of the abnormal discharge detection means is started after detecting that the differential value of the time change of the quantity of electricity or its envelope has become a predetermined value or less.

  The invention according to claim 12 includes an inverter circuit that turns on a discharge lamp serving as a light source by converting a DC voltage into a high-frequency AC voltage, detects an electrical characteristic of an output part or an input part of the inverter circuit, and normalizes the discharge lamp. In a discharge lamp lighting device comprising an abnormal discharge detecting means for detecting a difference in electrical characteristics between when the lamp is lit and when an abnormal discharge occurs due to incomplete connection of the inverter circuit output unit, as shown in FIGS. The discharge lamp lighting device is capable of burst dimming, and is characterized in that a mask is provided so that the abnormal discharge detection means does not detect when starting the discharge lamp during burst dimming.

  The invention of claim 13 includes an inverter circuit that turns on a discharge lamp as a light source by converting a DC voltage into a high-frequency AC voltage, detects an electrical characteristic of an output part or an input part of the inverter circuit, and normalizes the discharge lamp. In a discharge lamp lighting device comprising an abnormal discharge detecting means for detecting a difference in electrical characteristics between when the lamp is turned on and when an abnormal discharge occurs due to incomplete connection of the inverter circuit output unit, as shown in FIGS. The discharge lamp lighting device is capable of burst dimming, and outputs a false detection prevention signal in synchronization with the burst dimming signal.

  The invention of claim 14 is provided with an inverter circuit that turns on a discharge lamp as a light source by converting a DC voltage into a high-frequency AC voltage, detects an electrical characteristic of an output part or an input part of the inverter circuit, and normalizes the discharge lamp. In a discharge lamp lighting device comprising an abnormal discharge detecting means for detecting a difference in electrical characteristics between when lighting and when an abnormal discharge occurs due to incomplete connection of the inverter circuit output unit, as shown in FIGS. The discharge lamp lighting device is capable of burst dimming, and a mask is provided so that the abnormal discharge detection means does not detect when switching from fully lit to burst dimming or when switching from burst dimming to fully lit. Features.

  According to a fifteenth aspect of the present invention, there is provided an inverter circuit for turning on a discharge lamp serving as a light source by converting a DC voltage into a high-frequency AC voltage, and detecting an electrical characteristic of an output part or an input part of the inverter circuit, In a discharge lamp lighting device comprising an abnormal discharge detecting means for detecting a difference in electrical characteristics between when lighting and when an abnormal discharge occurs due to incomplete connection of the inverter circuit output unit, as shown in FIGS. The discharge lamp lighting device is capable of burst dimming, and outputs a false detection prevention signal in synchronization with a signal switched from full lighting state to burst dimming or from burst dimming to full lighting state. To do.

  The invention of claim 16 is an emergency lighting apparatus comprising the discharge lamp lighting device according to any one of claims 1 to 15.

  According to the present invention, it is possible to reliably detect abnormal discharge due to poor connection of the inverter circuit output unit without causing malfunction due to external noise or the like.

  According to the invention of claim 1, by detecting the output terminal voltage of the inverter circuit having a large characteristic change at the time of abnormal discharge occurrence, and detecting the difference from the normal lighting, without being affected by external noise, It is possible to reliably detect the occurrence of abnormal discharge.

  According to the second aspect of the present invention, since the detection can be performed by the voltage generated in the lamp current limiting element, it is not necessary to add a special detection circuit, and the configuration of the detection circuit can be greatly simplified. Further, since the lamp current detection circuit can be constituted only by the low voltage side of the inverter circuit secondary side, there is an advantage that the leakage current to the detection circuit can be minimized and the influence of the leakage current is almost eliminated.

  According to the invention of claim 3, by detecting the output power that is the product of the output terminal voltage of the inverter circuit and the lamp current, it is possible to detect reliably whether the load power change due to the occurrence of abnormal discharge is positive or negative. It becomes possible.

  According to the invention of claim 4 or 5, the accuracy is improved by detecting the abnormal discharge from one parameter by performing arithmetic processing using the two parameters of the output voltage of the inverter circuit and the lamp current. It becomes possible. In particular, the effect of increasing the detection accuracy can be obtained at the time of dimming lighting with a low lamp current.

  According to the invention of claim 6, detecting the input power on the primary side of the inverter circuit which is the low voltage side eliminates the need for a detection circuit on the secondary side which is the high voltage side, and eliminates leakage of output current. It becomes possible. Further, it is possible to make the circuit configuration simpler than that detected on the secondary side. Furthermore, even when a DC power source whose voltage varies such as a storage battery is used, highly accurate detection is possible.

  According to the seventh aspect of the present invention, it is possible to reliably detect the occurrence of abnormal discharge even in an inverter circuit in which the voltage of the DC power supply fluctuates by detecting a frequency change due to the occurrence of abnormal discharge. . In addition, reliable detection is possible even when the light is lit.

  According to the invention of claim 8, the detection of the secondary side characteristic is performed more than the invention of claim 5 by performing arithmetic processing using two parameters of the primary side characteristic and the secondary side characteristic of the inverter circuit. It is possible to simplify the circuit and to detect abnormal discharge with high accuracy.

  According to the ninth aspect of the present invention, by providing an abnormality detection mask at the time of starting the lamp, it is possible to eliminate the risk of determining that the change in electrical characteristics at the start in the normal state is abnormal without increasing the number of parts.

  According to the tenth aspect of the invention, by outputting the false detection prevention signal in synchronization with the start detection signal, it is possible to eliminate the risk of determining that the change in the electrical characteristics at the start in the normal state is abnormal.

  According to the eleventh aspect of the invention, since the abnormal discharge detection is started after detecting the initial change that occurs at the time of starting the lamp, the change in the electrical characteristics at the time of starting the lamp is determined to be abnormal without increasing the number of parts. You can eliminate fear.

  According to the twelfth aspect of the present invention, it is possible to eliminate the possibility that the normal state is erroneously detected as the abnormal discharge by providing the mask for the abnormal discharge detection in synchronization with the restart of the lamp during the burst dimming.

  According to the thirteenth aspect of the present invention, the false detection prevention signal can be output in synchronization with the restart of the lamp during the burst dimming, and the state change of the detection voltage can be eliminated. can get.

  According to the invention of claim 14, it is normal without increasing the number of parts by providing a mask when changing the lighting mode from the full lighting state to the burst dimming state or when changing the lighting mode from the burst dimming state to the full lighting state. It is possible to eliminate the possibility of erroneously detecting the state.

  According to the invention of claim 15, the number of parts is increased by outputting a false detection prevention signal when the lighting mode changes from the fully lit state to the burst dimming state or when the lighting mode changes from the burst dimming state to the fully lit state. Therefore, it is possible to eliminate the possibility of erroneously detecting the normal state.

(Embodiment 1)
FIG. 1 shows a basic configuration of Embodiment 1 of the present invention. Here, the DC voltage E is a DC power source such as a secondary battery, and the self-excited oscillation resonance voltage is boosted according to the turn ratio of the transformer Tf by an L-push pull inverter connected to the DC power source. It is output to the secondary side and supplied to the discharge lamp La via the current limiting ballast capacitor Cb. For example, a cold cathode lamp is used as the discharge lamp La.

Here, the configuration and operation of the L-push-pull inverter are well known, and the pair of transistors Tr1 and Tr2 are alternately turned on and off by the feedback winding of the transformer Tf, thereby converting the input DC voltage into a high-frequency AC voltage. . r1 and r2 are bias resistors of the transistors Tr1 and Tr2, Cr is a resonant capacitor,
L1 is a constant current inductor.

  The present embodiment is an example in which the voltage detection circuit 1 detects the voltage at the output terminal of the inverter circuit and detects the occurrence of abnormal discharge based on the difference from the normal lighting. FIG. 2 shows a specific example of the voltage detection circuit 1 that detects the voltage at the output terminal of the inverter circuit. The output side voltage of the current limiting ballast capacitor Cb connected to the secondary side of the transformer Tf is divided by resistors R1 and R2. The divided voltage is rectified by the diode D1, and further smoothed moderately by the capacitor C1 and the resistor R3, thereby detecting the peak value or effective value of the inverter output voltage.

  Here, when an abnormal discharge occurs due to a defective connection of the discharge lamp or the like, the waveform of the inverter output voltage changes as shown in FIG. 3, and the effective value and the peak value increase. This is because the inverter output voltage when the discharge lamp is normally lit is equal to the voltage Vla across the discharge lamp (hereinafter referred to as the lamp voltage), but the inverter output voltage when an abnormal discharge occurs includes the abnormal discharge voltage in addition to the lamp voltage. This is because Vg is added. Therefore, the voltage V1 of the capacitor C1 that detects the inverter output voltage rises relatively instantaneously as shown in FIG. When the resistance R3 is large with respect to the capacitance of the capacitor C1, peak detection is detected, and when the resistance R3 is small, it is close to effective value detection.

  The amount of change in the voltage V1, that is, the difference between when the lamp is normally lit and when an abnormal discharge occurs is detected by a capacitor C2 and a differential circuit of resistors R4 and R5 connected in series to the high voltage side of the capacitor C1. Since the capacitor C2 performs a direct current cut operation, if the voltage V1 is constant during normal lighting, the voltage V2 is not generated on the resistor R4 side of the capacitor C2. However, when the voltage of the capacitor C1 changes, a voltage V2 corresponding to the amount of change of the voltage V1 is generated.

  The voltage V2 rises with a time constant determined by the capacitor C2 and the resistors R4 and R5. If the voltage V1 at the time of occurrence of abnormal discharge is constant, the voltage V2 becomes a saturation voltage almost equal to the amount of change of the voltage V1. After reaching it, it will gradually fall and return to 0V again. Therefore, an output voltage V3 as shown in FIG. 3 is obtained by configuring the signal output circuit with the transistor Q1 and the resistor R6 so that a signal can be output in a section where the voltage V2 exceeds the predetermined threshold Vth. When the transistor Q1 is off, an H level signal corresponding to the control power supply voltage is output via the resistor R6. When the transistor Q1 is on, an L level signal is output.

  In the case of the circuit configuration of FIG. 2, the voltage detection threshold Vth is determined by the voltage dividing ratio between the base-emitter voltage Vbe of the transistor Q1 and the resistors R4 and R5. Capacitor C3 is for noise removal, and is set to an appropriate capacity so that transistor Q1 does not malfunction due to discharge noise or the like.

  With the configuration as described above, it is possible to reliably detect the occurrence of abnormal discharge due to poor connection of the discharge lamp. This embodiment is different from the conventional technique that detects a component having a frequency higher than the oscillation frequency of the inverter, such as “discharge pulse” or “discharge noise” generated by abnormal discharge, in a section that is sufficiently longer than the oscillation cycle of the inverter. Since the detection is based on the difference between the normal lighting and the occurrence of abnormal discharge, the voltage V1 of the capacitor C1 changes with a response speed equivalent to the oscillation period of the inverter with respect to disturbances such as external noise. Is superimposed, the voltage V1 changes instantaneously, but by connecting the capacitor C2 and the resistors R4 and R5 in series, the change in the difference detection voltage V2 becomes gradual, and the final signal output V3 is a discharge pulse or Less affected by discharge noise. That is, since the signal output V3 changes as the abnormal discharge continues for a certain period of time, it is possible to prevent malfunction due to external noise or the like and to realize reliable abnormal discharge detection. The protection operation at the time of detecting abnormal discharge is not particularly limited. For example, as shown in FIG. 1, the detection output of the voltage detection circuit 1 may be received to open the power switch S to stop the oscillation of the inverter circuit.

  In the present embodiment, the L-push-pull inverter circuit has been described as an example, but the configuration of the inverter circuit is not particularly limited, and may be a half-bridge circuit, for example. The element that limits the current flowing to the discharge lamp has been described with the ballast capacitor in the present embodiment, but is not particularly limited, and may be a leakage inductance of a transformer, for example. Further, in the present embodiment, the discharge lamp has been described by taking the cold cathode discharge lamp as an example. However, the discharge lamp is not particularly limited, and may be a hot cathode discharge lamp, for example. In any case, as long as the inverter output voltage increases when an abnormal discharge occurs, the circuit system, elements, and types of discharge lamps are not particularly limited.

  In addition, although FIG. 2 illustrates the configuration in which the difference in inverter output voltage is detected by the analog circuit configuration, for example, the detection circuit may be configured by a microcomputer or the like. In that case, if the voltages V1 and V2 are input to the analog / digital conversion port of the microcomputer, the element on the signal output V3 side than the capacitor C2 or the resistor R4 can be deleted, and the device can be downsized by reducing the number of parts. Can be achieved. When detecting with the voltage V1, in order to prevent malfunction due to external noise or the like, a function equivalent to the capacitor C2 in the analog circuit configuration is realized by performing software processing such as matching the detection results multiple times and masking. Can do.

  The present embodiment is an illuminating device including a secondary battery that serves as an inverter power source when a commercial power supply is interrupted, a charging circuit that charges the secondary battery when the commercial power is energized, and an emergency lamp such as a guide light fixture including the illuminating device. It is possible to apply to a lighting fixture for an automobile.

  Any of the embodiments described below can be applied to these lighting apparatuses and lighting fixtures as in this embodiment.

(Embodiment 2)
FIG. 4 shows a basic configuration of the second embodiment of the present invention. The present embodiment is an example in which the current flowing through the discharge lamp La is detected by the current detection circuit 2, and the occurrence of abnormal discharge is detected based on the difference from the normal lighting.

  In the first embodiment, the voltage at the output terminal of the inverter circuit is detected. However, when the voltage detection circuit 1 as shown in FIG. 2 is provided at the output terminal of the inverter circuit, the leakage current to the voltage detection circuit 1 Will occur. This leakage current is desirably sufficiently small compared to the current flowing through the discharge lamp La (hereinafter referred to as lamp current), but cannot be ignored when the impedance of the discharge lamp La is very high. For example, in the case of a hot cathode fluorescent lamp, since the lamp current is several hundred mA and the lamp voltage is around 100 V, the lamp impedance is several hundred Ω to several kΩ. On the other hand, when the cold cathode fluorescent lamp is lit, the lamp current is several mA and the lamp voltage is several hundred volts, so the lamp impedance is several tens kΩ to several hundred kΩ. Therefore, even if the impedance of the voltage detection circuit is set to several MΩ, a circuit current of about several tens of μA flows. Therefore, when the cold cathode fluorescent lamp is turned on, several percent of the lamp current leaks to the voltage detection circuit. become. In order to reduce this circuit current, it is sufficient to increase the impedance of the voltage detection circuit. However, since high impedance tends to cause malfunction due to external noise or the like, a leakage current of about several tens of μA is unavoidable in practice. .

  FIG. 5 shows a specific example of the current detection circuit 2 used in the present embodiment. The peak value or effective value of the lamp current is detected by rectifying the voltage across the lamp current detection resistor R7 connected in series with the discharge lamp La by the diode D1 and further smoothing it appropriately by the capacitor C1 and the resistor R3.

  Here, when abnormal discharge occurs due to poor connection of the discharge lamp, the waveform of the lamp current changes as shown in FIG. Since the abnormal discharge generation part has an impedance component, the effective value of the lamp current tends to decrease. However, since the discharge occurs in the air, the impedance has a positive characteristic and the peak value tends to increase. Therefore, when the value of the resistor R3 is larger than the capacitance of the capacitor C1, peak detection is performed, and the voltage of the capacitor C1 rises due to the occurrence of abnormal discharge as shown by the voltage V1 in FIG. Similar to FIG. 3 of the first embodiment, the voltage change amount of the capacitor C1, that is, the difference between the normal lighting and the occurrence of abnormal discharge is detected by the differentiation circuit similar to that of FIG. 2 of the first embodiment. In a section where V2 exceeds the threshold value Vth, the transistor Q1 is turned on, and an abnormal discharge detection signal is obtained.

  When the value of the resistor R3 is smaller than the capacitance of the capacitor C1, the effective value is detected, and the voltage of the capacitor C1 decreases due to the occurrence of abnormal discharge as shown by the voltage V1 ′ in FIG. 8, and the voltage V2 ′ is a negative potential. Become. In this case, by configuring the differentiating circuit as shown in FIG. 7, the transistor Q1 is turned on in a section where the voltage V2 ′ is lower than the threshold value Vth, and an abnormal discharge detection signal can be obtained.

  Although the present embodiment has been described by taking an L-push-pull inverter circuit as an example as in the first embodiment, the configuration of the inverter circuit is not particularly limited, and may be, for example, a half-bridge circuit. The element that limits the current flowing to the discharge lamp has been described with the ballast capacitor in the present embodiment, but is not particularly limited, and may be a leakage inductance of a transformer, for example. In addition, the discharge lamp has been described by way of example of a cold cathode discharge lamp with a high impedance that can obtain a particularly great effect in the present embodiment, but is not particularly limited, and may be a hot cathode discharge lamp, for example. In any case, the circuit system and the type of the discharge lamp are not particularly limited as long as the lamp current changes when an abnormal discharge occurs.

  Further, the means for detecting the difference in lamp current may be constituted by, for example, a microcomputer as in the first embodiment.

(Embodiment 3)
FIG. 9 shows a basic configuration of the third embodiment of the present invention. The present embodiment is an example in which a voltage generated in a current limiting ballast capacitor provided on the output side of an inverter circuit is detected, and an abnormal discharge is detected based on a difference from the normal lighting.

  As described in the prior art, an L-push-pull inverter that easily obtains a high-frequency AC voltage from a low-voltage DC power supply is well known as a device for lighting a cold cathode discharge lamp. In this device, the resonant voltage of self-excited oscillation is boosted according to the turns ratio of the transformer, output to the secondary side, and connected to the discharge lamp via a current limiting ballast capacitor. The ballast capacitor Cb is generally provided on the high-voltage side in order to reduce the influence on the leakage current and lighting performance due to the parasitic capacitance of the wiring by setting one side of the discharge lamp connecting portion as a low-voltage portion. The ballast capacitor is divided and a capacitor Cb ′ is inserted on the low voltage side in addition to the capacitor Cb connected to the high voltage side of the discharge lamp, and abnormal voltage is detected by detecting the voltage of the low voltage side ballast capacitor Cb ′. Detect outbreaks.

  FIG. 10 is an explanatory diagram showing how the voltage on the transformer secondary side is divided. The transformer secondary voltage during normal lighting is the sum of the lamp voltage Vla, the high-voltage ballast capacitor voltage Vb, and the low-voltage ballast capacitor voltage Vb '. The voltage division ratio between Vb and Vb 'is set by the capacitance ratio between the capacitors Cb and Cb'. Here, when abnormal discharge occurs due to the discharge lamp being disconnected, etc., abnormal discharge voltage Vg is generated in addition to these voltages, but the L-push-pull inverter has the transformer secondary voltage almost constant regardless of the load state. For this reason, the respective partial pressure ratios change. That is, since the voltage dividing ratio of the ballast capacitor in the transformer secondary voltage is reduced, it is possible to detect the occurrence of abnormal discharge by detecting this difference with the voltage Vb 'on the capacitor Cb' side.

  FIG. 11 is obtained by adding a current detection unit 2 between the capacitor Cb and the transformer low-voltage side in the configuration of FIG. In general, the current detection element often uses a resistor. However, as described in the second embodiment, when an abnormal discharge occurs, the effective value of the lamp current decreases. Accordingly, since the voltage Vr generated in the current detection unit also decreases, by detecting the sum of the voltage Vr generated in the current detection unit and the voltage Vb ′ of the low-voltage side ballast capacitor, normal lighting and abnormal discharge are detected. The difference with time can be made larger, and the detection accuracy can be improved as compared with the configuration of FIG.

  In this embodiment, the inverter circuit has been described by taking an L-push-pull inverter as an example. However, the circuit system is particularly limited as long as the transformer output voltage is substantially constant even when the load state changes. is not. The lamp current limiting element is also connected to the capacitor as an example. However, the lamp current limiting element is not particularly limited as long as similar elements are inserted on the high voltage side and the low voltage side. For example, an element corresponding to the high voltage side ballast capacitor Cb is a transformer. Even if the element corresponding to the leakage inductance and the ballast capacitor Cb ′ on the low voltage side is constituted by an inductor, the same effect can be obtained. Further, in the present embodiment, the discharge lamp has been described by taking a cold cathode discharge lamp as an example. However, the discharge lamp is not particularly limited, and may be a hot cathode discharge lamp, for example.

  Also, the means for detecting the difference in lamp current is not particularly limited, and it may be constituted by an analog circuit or a microcomputer as in the first and second embodiments.

(Embodiment 4)
FIG. 12 shows a basic configuration of the fourth embodiment of the present invention. This embodiment is an example in which the voltage at the output terminal of the inverter circuit and the current flowing through the discharge lamp are detected, and the occurrence of abnormal discharge is detected by the output power of the inverter circuit, which is the product of these detected values.

  In the first embodiment, an example in which the voltage at the output end of the inverter circuit is detected, and in the second embodiment, an example in which the current flowing through the discharge lamp is detected. However, this embodiment is a combination thereof. As shown in FIG. 12, a voltage detection circuit 1 that detects the output terminal voltage of the inverter circuit, a current detection circuit 2 that detects the lamp current, and a power calculation circuit 3 that calculates the product of the detection output of the lamp voltage and the lamp current. , The output power of the inverter circuit is calculated.

  FIG. 13 shows operation waveforms of this embodiment. As described in the first and second embodiments, when an abnormal discharge occurs, the output voltage of the inverter circuit increases in both the effective value and the peak value, but the effective value of the lamp current decreases and the peak value increases. To do. Therefore, if the product of the output voltage of the inverter circuit and the peak value of the lamp current is obtained, the calculation result of the inverter output power at the time of abnormal discharge will be higher than that at normal lighting, so the difference is detected. By doing so, the occurrence of abnormal discharge can be detected.

  When obtaining the product of the output terminal voltage of the inverter circuit and the effective value of the lamp current, as shown by the broken line in FIG. 14 depending on which of the output terminal voltage increase rate and the lamp current decrease rate is dominant. The direction of change of the product value changes. Since this depends on the design of the inverter circuit, the detection direction may be set in accordance with the design of the lighting device, and abnormal discharge occurs due to the difference in inverter output power as in the case of obtaining the peak value product. Can be detected.

  Although the present embodiment has been described by taking an L-push-pull inverter circuit as an example, the configuration of the inverter circuit is not particularly limited as in the first and second embodiments, and may be, for example, a half bridge circuit. Also, the element that limits the current flowing to the discharge lamp is described as a capacitor in the present embodiment, but is not particularly limited, and may be a leakage inductance, for example. Further, in the present embodiment, the discharge lamp has been described by taking a cold cathode discharge lamp as an example. However, the discharge lamp is not particularly limited, and may be a hot cathode discharge lamp, for example. In any case, the circuit system and the type of the discharge lamp are not particularly limited as long as the inverter output power increases when abnormal discharge occurs.

  Also, the means for detecting the difference in inverter output power may be constituted by, for example, a microcomputer as in the first and second embodiments.

(Embodiment 5)
FIG. 15 shows a basic configuration of the fifth embodiment of the present invention. The present embodiment is a development of the fourth embodiment, and detects the occurrence of abnormal discharge by detecting the voltage at the output terminal of the inverter circuit and the current flowing through the discharge lamp and performing an operation on the detected value. It is an example.

  As described in the fourth embodiment, when an abnormal discharge occurs, the peak value and the effective value of the output terminal voltage of the inverter circuit increase, but the peak value of the lamp current increases and the effective value decreases. When the product of the effective values of is obtained, the direction of change at the occurrence of abnormal discharge changes depending on whether the output voltage increase rate or the lamp current decrease rate is dominant. In the fourth embodiment, the example of setting the detection direction (positive or negative) of occurrence of abnormal discharge according to the design of the lighting device has been described. However, the present embodiment is a detection method that does not depend on the design of the lighting device.

  Specifically, as shown in FIG. 15, the inverter output side voltage is divided by the lamp current by the divider 4 to calculate the equivalent resistance Rout on the inverter output side, and the comparator 5 compares it with the reference Rout. Since there is no abnormal discharge voltage Vg during normal lighting, the equivalent resistance Rout on the inverter output side is equal to the equivalent resistance Rla (= Vla / Ila) of the lamp. On the other hand, when an abnormal discharge occurs, the inverter output terminal voltage is the sum of the lamp voltage Vla and the abnormal discharge voltage Vg.

  FIG. 16 shows the inverter output side equivalent resistance obtained from the experimental results when the dimming lighting is performed by changing the inverter input voltage in the cold cathode discharge lamp lighting device. It can be seen that it is possible to distinguish between the occurrence of abnormal discharge and the normal lighting by determining whether it is high or low with respect to the reference equivalent resistance Rout.

  In FIG. 17, the horizontal axis in FIG. 16 is replaced with the lamp current. From this result, it can be seen that when an abnormal discharge occurs, the lamp current tends to be lower than that during normal lighting, and the equivalent resistance on the inverter output side with respect to the inverter input voltage significantly increases due to the occurrence of the abnormal discharge. In particular, when dimming the inverter input voltage is low, the tendency becomes remarkable, and it can be seen that this embodiment is particularly effective.

  FIG. 18 shows another configuration example that can obtain the same effect as that of FIG. In FIG. 15, the inverter output voltage is divided by the lamp current to calculate the equivalent impedance. However, in FIG. 18, the detected value of the inverter output voltage is multiplied by a predetermined coefficient K by the coefficient multiplier 6 and the calculation is performed. It is an example which compares a result and lamp current.

  FIG. 19 shows an example in which the coefficient K in FIG. 18 is given so that the detected value of the inverter output voltage is 80 when the detected value of the lamp current is 100. As a result of the experiment, the change rates of the inverter output voltage and the lamp current at the time of abnormal discharge were 145% and 80%, respectively, compared with the normal lighting.

  Here, if a coefficient K is set such that the magnitude relationship between the inverter output voltage and the lamp current is reversed between when the lamp is normally lit and when an abnormal discharge occurs, the detected values change as shown in FIG. Therefore, if, for example, a comparator is used as the comparator 5 in FIG. 18 and one input is the lamp current and the other input is the inverter output voltage multiplied by the coefficient K, the normal lighting and abnormal discharge occur. The output of the comparator is inverted, and the occurrence of abnormal discharge can be detected.

  Although FIG. 18 shows an example in which the detected value of the inverter output terminal voltage is multiplied by the coefficient K, the same effect can be obtained by multiplying the detected value of the lamp current by the coefficient 1 / K.

  Although the present embodiment has been described by taking an L-push-pull inverter circuit as an example, the configuration of the inverter circuit is not particularly limited as in the first and second embodiments described above. good. Also, the element that limits the current flowing to the discharge lamp is described as a capacitor in the present embodiment, but is not particularly limited, and may be a leakage inductance, for example. Further, in the present embodiment, the discharge lamp has been described by taking a cold cathode discharge lamp as an example. However, the discharge lamp is not particularly limited, and may be a hot cathode discharge lamp, for example. In any case, as long as the equivalent resistance of the inverter output increases when abnormal discharge occurs, the circuit system, the type of the discharge lamp, and the like are not particularly limited.

  Further, although the divider 4 and the comparator 5 in FIG. 15 and the coefficient multiplier 6 in FIG. 18 have been described as analog circuits in this embodiment, they may be constituted by, for example, a microcomputer.

(Embodiment 6)
FIG. 20 shows a sixth embodiment of the present invention. In this embodiment, the primary side of the inverter circuit, that is, the current flowing in the DC power supply and the output voltage of the DC power supply are detected, and the abnormality corresponding to the output power of the DC power supply is detected by the difference between the normal lighting and the abnormal discharge occurrence. It is an example which detects discharge. That is, by obtaining the product of the input voltage from the DC power source detected by the input voltage detection circuit 1 ′ to the inverter circuit and the input current from the DC power source detected by the input current detection circuit 2 ′ to the inverter circuit, The input power from the power source to the inverter circuit is calculated, and abnormal discharge is detected based on the difference between normal lighting and abnormal discharge.

  In the first embodiment, the voltage at the output terminal of the inverter circuit is detected. However, when the voltage detection circuit 1 as shown in FIG. 2 is provided at the output terminal of the inverter circuit, a leakage current to the detection circuit is generated. Resulting in. This leakage current is desirably sufficiently small compared to the lamp current, but cannot be ignored when the impedance of the discharge lamp is very high. For example, when the cold cathode fluorescent lamp is turned on, as described in the second embodiment, about several percent of the lamp current may leak to the voltage detection circuit.

  In the fourth embodiment, the output voltage and the output current are detected as the output of the inverter circuit (secondary side of the transformer), and the power is converted, so that the power when the abnormal discharge state occurs is increased as compared with the normal discharge. The abnormal discharge was detected in the above, but this also detects the output voltage of the inverter circuit. Further, when the voltage detection unit is inserted, a leakage current flows to the voltage detection unit, so that the current to the discharge lamp becomes smaller than when the voltage detection unit is not inserted. Therefore, in order to flow a predetermined current through the discharge lamp, it is necessary to supply a current obtained by adding the leakage current to the voltage detection unit. That is, if the voltage detection unit is inserted on the secondary side of the transformer Tf, the shape of the transformer becomes large.

  Therefore, in this embodiment, since the output power of the inverter circuit increases at the time of abnormal discharge, the input power of the inverter circuit increases as compared with that at the time of normal discharge as shown in FIG. ing.

  In addition, when the DC power source is a battery, the battery voltage varies depending on the capacity of the battery, so it is difficult to determine abnormal discharge only by changing the input current. Therefore, it is possible to detect the input voltage and the input current with high accuracy by detecting the abnormal discharge by converting it to the input power.

  As a means for voltage detection or current detection, it can be simply configured as a resistor, but it is not limited to a resistor.

  In addition, although this embodiment demonstrated the circuit of the L-push pull inverter similarly to Embodiment 1, the structure of an inverter circuit is not specifically limited, For example, a half bridge circuit etc. may be sufficient. Also, the element that limits the current flowing to the discharge lamp is described as a capacitor in the present embodiment, but is not particularly limited, and may be a leakage inductance, for example. Further, the discharge lamp has been described by taking the cold cathode discharge lamp as an example in the drawing of the present embodiment, but is not particularly limited, and may be a hot cathode discharge lamp, for example. In any case, the circuit system and the type of the discharge lamp are not particularly limited as long as the inverter input power increases when abnormal discharge occurs.

  Also, the method for detecting the input power may be constituted by, for example, a microcomputer as in the first embodiment.

(Embodiment 7)
FIG. 22 shows a seventh embodiment of the present invention. In this embodiment, the frequency of the voltage applied to the discharge lamp is detected to detect normal discharge and abnormal discharge.

  FIG. 24 schematically shows when the output voltage waveform of the inverter circuit is normally discharged and when abnormal discharge occurs. When the frequency during normal discharge is A (Hz) and the frequency during abnormal discharge is B (Hz), the frequency during normal lighting in the experiment was about 49 kHz, whereas when abnormal discharge occurs, the frequency is about 53 kHz. It was. Here, as shown in FIG. 22, it is possible to detect the occurrence of abnormal discharge by providing the frequency detection circuit 7 at the output of the inverter circuit and detecting the difference between the normal lighting frequency and the abnormal discharge frequency.

  Further, as shown in FIG. 23, it is also possible to detect the frequency with the voltage on the primary side of the transformer Tf. The frequency detection circuit 7 may determine the frequency using a microcomputer or the like based on voltage division by a resistor connected in series or voltage division by a capacitor. Further, the frequency can be detected not by voltage but by current.

  Although the present embodiment has been described by taking an L-push-pull inverter circuit as an example as in the first embodiment, the configuration of the inverter circuit is not particularly limited, and may be, for example, a half bridge circuit. Also, the element that limits the current flowing to the discharge lamp is described as a capacitor in the present embodiment, but is not particularly limited, and may be a leakage inductance, for example. Further, the discharge lamp has been described by taking the cold cathode discharge lamp as an example in the drawing of the present embodiment, but is not particularly limited, and may be a hot cathode discharge lamp, for example. In any case, the circuit system and the type of the discharge lamp are not particularly limited as long as the frequency changes when an abnormal discharge occurs.

(Embodiment 8)
FIG. 25 shows an eighth embodiment of the present invention. In the present embodiment, an abnormal discharge state is detected by detecting changes in the input current and output current of the inverter circuit during normal discharge and when abnormal discharge occurs.

  Table 1 (a) shows an example of actual measured values of the input current value and output current value of the inverter circuit during normal lighting and abnormal discharge. Here, in order to compare the input current value and the output current value, the output current is multiplied by K, and the coefficient K is set so that the input current value <the output current × K at the time of normal lighting. Here, the coefficient K is assumed to be 250. The values at this time are shown in Table 1 (b). In Table 1 (b), the input current is smaller than the output current during normal discharge, whereas the input current is greater than the output current during abnormal discharge.

  Table 1 (c) also shows an example of measured values of the input current value and output current value of the inverter circuit during normal lighting and abnormal discharge. The difference between Table 1 (a) and Table 1 (c) is that the values in Table 1 (a) are normal discharge <abnormal discharge values in the input current, whereas Table 1 (c) is normal discharge. That is, when time> abnormal discharge. Again, as in Table 1 (a), the output current is multiplied by K to compare the input current value and the output current value, and the coefficient K is set so that the input current value <the output current × K when normally lit. Here, the coefficient K is assumed to be 250. The values at this time are shown in Table 1 (d). Again, in Table 1 (c), input current <output current × K during normal discharge, whereas input current> output current × K during abnormal discharge.

  As described above, the input current and the output current are detected, and an appropriate coefficient K is selected so that the input current value <output current value × K during normal discharge, so that the input current value> output current value during abnormal discharge. XK. The abnormal discharge state is detected by detecting the change in the magnitude relationship between the input current value and the output current value × K during the normal discharge and the abnormal discharge.

  Although shown in a block diagram in FIG. 25, the output current value can be multiplied by an arbitrary K by using an operational amplifier to multiply the output current value by a factor K, and a comparator may be used as the comparison means. Further, each current detection can be easily configured by using a resistor. In the above description, the output current is multiplied by K, but the same can be said by multiplying the input current by 1 / K.

  In addition, although this embodiment demonstrated the circuit of the L-push pull inverter similarly to Embodiment 1, the structure of an inverter circuit is not specifically limited, For example, a half bridge circuit etc. may be sufficient. Also, the element that limits the current flowing to the discharge lamp is described as a capacitor in the present embodiment, but is not particularly limited, and may be a leakage inductance, for example. Further, in the present embodiment, the discharge lamp has been described by taking a cold cathode discharge lamp as an example. However, the discharge lamp is not particularly limited, and may be a hot cathode discharge lamp, for example. In either case, as long as the inverter input current and the output current change when an abnormal discharge occurs, the circuit system and the type of the discharge lamp are not particularly limited.

(Embodiment 9)
FIG. 26 shows a ninth embodiment of the present invention. In the present embodiment, a mask is provided in the abnormal discharge detection means at the time of starting the lamp so as to prevent erroneous detection of a change in electrical characteristics at the time of normal lamp starting.

  FIG. 27 shows an example of a change in lamp voltage at the time of starting the lamp. As can be seen from FIG. 27, the lamp voltage rapidly rises at the start and gradually stabilizes at a predetermined lamp voltage V0. At this time, if the voltage at the output terminal of the inverter circuit is detected as shown in the first embodiment and the occurrence of abnormal discharge is detected based on the difference during normal lighting, the lamp voltage is rapidly increased. Since it cannot be distinguished from the case where discharge has occurred, there is a risk of erroneous detection.

  Therefore, in this embodiment, the abnormal discharge detection based on the difference detection is not performed at the time of starting the lamp, and the abnormality detecting means is operated after the lamp is stably lit.

  For example, in FIG. 26, there is a method of providing a mask for detecting abnormal discharge due to a difference from the time of starting the lamp to at least time T2 when the lamp voltage is stabilized.

  In the detection circuit shown in FIG. 2 of the first embodiment, as shown in FIG. 28, it is detected that an abnormal discharge has occurred by connecting the collector-side voltage V3 of the transistor Q1 to, for example, the microcomputer IC1, and a lamp lighting operation is performed. Is stopped when the microcomputer IC1 does not detect the occurrence of an abnormality even when a low signal indicating that an abnormal discharge has occurred as a voltage V3 from the lamp start to a predetermined time T2 is generated in the microcomputer IC1. Is provided to prevent erroneous detection at the time of starting the lamp.

  By setting the mask time to at least the time T1 when the lamp voltage is rising, the mask time can be set shorter than the time T2 until the lamp voltage V0 is stabilized, and the mask can be released quickly.

  Here, the case where a mask is set for lamp voltage detection has been described as an example, but any of the detection methods described in the above embodiments is effective.

(Embodiment 10)
FIG. 29 shows a tenth embodiment of the present invention. In the present embodiment, it is detected that the discharge lamp La is started, and an erroneous detection prevention signal is output in synchronization with the signal to prevent erroneous detection of a change in electrical characteristics at the time of normal lamp start.

  First, when the lamp is started, the lamp voltage increases as shown in FIG. 27 described above. Therefore, in the circuit of FIG. 2, the voltages V1, V2, and V3 of each part operate as shown in the time chart of FIG. The abnormal discharge is erroneously detected by the change of the voltage V3.

  Therefore, in FIG. 29 of the present embodiment, a resistor R7 is provided as a lamp current detecting means in series with the discharge lamp La, and the detected voltage is rectified and smoothed by the diode D2 and the capacitor C4. The voltage Vc4 of the capacitor C4 is input to the microcomputer IC1. As a result, when the discharge lamp La is started and a lamp current flows, a voltage Vc4 is generated in the capacitor C4, and the microcomputer IC1 detects that the voltage Vc4 of the capacitor C4 is equal to or higher than a reference value Vth4 preset by the microcomputer IC1. Detect and recognize that La has started.

  When the microcomputer IC1 recognizes that the lamp La has started, the microcomputer IC1 further outputs a signal V4 having a preset voltage and time. This signal V4 is input to the switch element Q4 in FIG. Then, the switch element Q4 receives the signal V4 and is turned on. Therefore, the transistor Q1 does not turn on while the switch element Q4 is on. Therefore, even if the voltage V1 changes as shown in FIG. 31, the voltage V3 maintains the H level, so that the lamp starting operation is not erroneously detected as an abnormal discharge. Here, the time T3 of the false detection prevention signal V4 from the microcomputer IC1 for turning on the switch element Q4 is set to be longer than the time (time T1 in FIG. 27) when the electrical characteristics of the lamp La (here, the lamp voltage) do not increase. Keep it.

  Although the lamp voltage detection is described here, it is effective in any of the detection methods shown in the first to eighth embodiments.

(Embodiment 11)
FIG. 32 shows the operation of the eleventh embodiment of the present invention. In the present embodiment, after detecting that the amount of change in the electrical characteristics or the differential value of the envelope has become a predetermined value or less, the operation of the abnormal discharge detection means is started so as not to cause erroneous detection of abnormal discharge detection. This is an example. Here, the configuration of the voltage detection circuit may be the same as that of FIG. 28, and the configuration of the main circuit may be the same as that of FIG.

  In the circuit of FIG. 28, when the lamp is started, the voltages V1, V2, and V3 of the respective parts change as shown in the time chart of FIG. Therefore, the microcomputer IC1 recognizes that an abnormal discharge has occurred due to the change in the voltage V3 from the H level to the L level due to a change in electrical characteristics (in this case, a change in the lamp voltage) due to the lamp start. As a method for avoiding this, the voltage V3 is changed only after once detecting a change in the voltage V3 (for example, H level → L level → H level) when the discharge lamp La is started on the software of the microcomputer IC1. The detection operation is masked so that it is not regarded as abnormal discharge. After that, if a change such as H level → L level occurs in the voltage V3, it is considered that abnormal discharge has occurred. This makes it possible to prevent erroneous detection when starting the lamp.

  Although the lamp voltage detection is described here, it is effective in any of the detection methods shown in the first to eighth embodiments.

Embodiment 12
FIG. 33 shows a twelfth embodiment of the present invention. In the configuration of FIG. 26 described above, the power switch S that is closed when normal and open when abnormal is a switching element Q2 that is periodically turned on and off during dimming. The switching element Q2 is opened when abnormal, and closed when fully lit.

  In the present embodiment, a change in the electrical characteristics of the lamp when the lamp shifts from the off state to the on state during burst dimming is prevented from being erroneously detected as an abnormal discharge state. Since the burst dimming is performed by turning on and off the switching element Q2 in FIG. 33 at a constant period, the microcomputer IC1 outputs a signal for turning on and off the switching element Q2. Thus, since the microcomputer IC1 controls the timing of the burst dimming, it is possible to predict the timing at which the change in the electrical characteristics of the lamp occurs when the lamp shifts from the unlit state to the lit state during the burst dimming. By masking abnormal discharge detection at that timing, erroneous detection can be prevented. The configuration shown in FIG. 28 can be used for the configuration of the voltage detection circuit 1.

  FIG. 34 schematically shows burst dimming. Burst dimming is a method in which the lamp brightness is averaged to be dimmed by blinking the lamp at a predetermined cycle (a cycle in which flicker and blinking cannot be recognized visually when the frequency is approximately 100 Hz or higher). In burst dimming, since the lamp is once extinguished, at the instant when it is started next time, as shown in FIG. 34, a higher voltage (generally referred to as a re-ignition voltage) is generated in each cycle as shown in FIG. A high voltage due to the re-ignition voltage settles to a stable voltage in several cycles as shown in FIG.

  Here, when the discharge lamp La is in the initial start-up state, it takes some time for the lamp temperature to stabilize, and in the case of a cold cathode lamp, it takes about several seconds for the lamp voltage to stabilize. However, when stable by burst dimming, since the lamp temperature is already stable and in an equilibrium state, the time required for the lamp voltage to stabilize is shortened. For this reason, it is possible to shorten the mask for preventing erroneous detection so that it can be quickly detected. Further, in the lighting period (T4 + T5 period) at the time of burst dimming, in order to detect the abnormal discharge state occurring during this period, the voltage is determined by the resistors R1 to R5 and the capacitors C1 to C3 of the voltage detection circuit (FIG. 28). The time constant τ for driving the element Q1 needs to be sufficiently smaller than T4 + T5. At this time, a mask is provided in the interval T4 so as not to erroneously detect abnormal discharge detection when a re-ignition voltage is generated at the time of lamp start in burst dimming. Here, as shown in FIG. 34, the mask timing is set to be the same as the timing at which the switching element Q2 changes from OFF to ON and includes at least the T4 interval. At this mask timing, the microcomputer IC1 stops detecting abnormal discharge, so that no erroneous detection occurs.

  Although the lamp voltage detection is described here, it is effective in any of the detection methods shown in the first to eighth embodiments.

(Embodiment 13)
FIG. 35 shows the configuration of the voltage detection circuit according to the thirteenth embodiment of the present invention. The configuration of the main circuit is the same as in FIG. In the present embodiment as well, a change in the electrical characteristics of the discharge lamp La when the discharge lamp La shifts from the unlit state to the lit state during burst dimming is prevented from being erroneously detected as an abnormal discharge state. Since the burst dimming is performed by turning on and off the switching element Q2 in FIG. 33 at a constant period, the microcomputer IC1 outputs a signal for turning on and off the switching element Q2 of the main circuit. In the present embodiment, a signal for turning on / off the switching element Q5 of FIG. 35 from the microcomputer IC1 is set to be output in synchronization with the on / off signal of the switching element Q2 as shown in FIG. That is, when the switching element Q5 is in the on state, the switching element Q1 is in the off state even if the voltage V1 changes. Thus, when the lamp voltage changes as in burst dimming, the false detection prevention signal is output in synchronization with the burst dimming on / off signal Q2, thereby erroneously detecting normal operation as an abnormal discharge state. Can be prevented.

  Although the lamp voltage detection is described here, it is effective in any of the detection methods shown in the first to eighth embodiments.

(Embodiment 14)
FIG. 37 shows the configuration of the voltage detection circuit according to the fourteenth embodiment of the present invention. A series circuit of the capacitor C5 and the switch element Q6 is connected in parallel with the capacitor C1, and the time constant of the voltage V1 can be switched. The switch element Q6 is controlled by a signal from the microcomputer IC1. In the present embodiment as well, during burst dimming, a change in the electrical characteristics of the lamp when the lamp transitions from the off state to the on state is prevented from being erroneously detected as an abnormal discharge state. The configuration of the main circuit is the same as in FIG.

  In the present embodiment, the switch element Q6 is turned off at the time of full lighting by a signal from the microcomputer IC1, and the switch element Q6 is turned on at the time of burst dimming. That is, at the time of burst dimming, the capacitor C5 is connected in parallel to the capacitor C1 as compared with the case of full lighting, so that the time constant τ for driving the switching element Q1 becomes large. Here, the time constant τ determined by the resistors R1 to R5 and the capacitors C1 to C5 is set to be sufficiently larger than the cycle of burst dimming. Further, as shown in FIG. 38, the voltage V3 is not changed by the change in the electric characteristics of the lamp at the time of burst dimming during normal lighting, and the voltage after the burst dimming state continues for several cycles when abnormal discharge occurs. By setting V3 to change, a normal burst dimming state can be prevented from being erroneously detected.

  According to the present embodiment, it is possible to eliminate the risk of erroneously detecting an abnormal state by changing the time constant of the change in electric characteristics of the lamp during burst dimming. In addition, since the time constant is larger than in the twelfth and thirteenth embodiments, the noise tolerance is increased.

  Although the lamp voltage detection is described here, it is effective in any of the detection methods shown in the first to eighth embodiments.

(Embodiment 15)
In this embodiment, a change in the electrical characteristics of the lamp when the lighting mode is changed from the full lighting state to the burst dimming state and from the burst dimming state to the full lighting state is prevented from being erroneously detected as an abnormal discharge state. FIG. 39 shows a timing chart of the voltages V1, V2, and V3 of each part of the voltage detection circuit when the lighting mode is changed from all lighting state → burst dimming state → all lighting state. Here, the configuration of the voltage detection circuit may be the same as that of FIG. 28, and the configuration of the main circuit may be the same as that of FIG.

  When the lighting mode is changed from the burst dimming state to the full lighting state, the voltage V1 rises. Therefore, the voltage V2 obtained by differentiating the voltage V1 changes, and the voltage V3 becomes L level in a section exceeding the threshold value Vth. That is, the operation becomes the same as when abnormal discharge detection is activated, and there is a possibility of erroneous detection.

  Therefore, at least when the lighting mode changes from the burst dimming state to the full lighting state, an abnormal discharge state is erroneously detected by providing a mask in the microcomputer IC1 during a period such as the mask timing of FIG. Do not.

  In addition, when the lighting mode is changed from the fully lit state to the burst dimming state, the lamp temperature decreases, so the lamp voltage may change depending on the burst dimming on / off ratio. . Therefore, it is desirable to provide a mask that does not erroneously detect abnormal discharge as shown in FIG. 40 even when the lighting mode is changed from the full lighting state to the burst dimming state.

  Although the lamp voltage detection is described here, it is effective in any of the detection methods shown in the first to eighth embodiments.

(Embodiment 16)
In this embodiment, a change in the electrical characteristics of the lamp when the lighting mode is changed from the full lighting state to the burst dimming state and from the burst dimming state to the full lighting state is prevented from being erroneously detected as an abnormal discharge state. The configuration of the voltage detection circuit may be the same as in FIG. 35, and the configuration of the main circuit may be the same as in FIG.

  The microcomputer IC1 performs control to switch the lighting mode from the full lighting state to the burst dimming state and from the burst dimming state to the full lighting state. Therefore, a signal for turning on / off the switching element Q5 of FIG. 35 is output from the microcomputer IC1 in synchronization with the control for switching the lighting mode. That is, when switching the lighting mode, the switching element Q5 is turned on for a predetermined time in accordance with the mask timing of FIG. 40, so that the switching element Q1 is turned off even if the voltage V1 of FIG. 35 changes. It is possible to prevent erroneous detection of a change in lamp voltage due to switching of the lighting mode as abnormal discharge.

  Although the lamp voltage detection is described here, it is effective in any of the detection methods shown in the first to eighth embodiments.

  Each of the embodiments described above is a lighting device including a secondary battery that serves as a power source for an inverter when a commercial power failure occurs, a charging circuit that charges the secondary battery when the commercial power is energized, and a guide light fixture including the lighting device. It can be applied to emergency lighting equipment.

It is a circuit diagram which shows the whole structure of Embodiment 1 of this invention. It is a circuit diagram which shows the structure of the detection circuit of Embodiment 1 of this invention. It is an operation | movement waveform diagram of Embodiment 1 of this invention. It is a circuit diagram which shows the whole structure of Embodiment 2 of this invention. It is a circuit diagram which shows the structure of the detection circuit of Embodiment 2 of this invention. It is an operation | movement waveform diagram of Embodiment 2 of this invention. It is a circuit diagram which shows the structure of the detection circuit of the modification of Embodiment 2 of this invention. FIG. 8 is an operation waveform diagram of the detection circuit of FIG. 7. It is a circuit diagram which shows the whole structure of Embodiment 3 of this invention. It is operation | movement explanatory drawing of Embodiment 3 of this invention. It is a circuit diagram which shows the structure of the modification of Embodiment 3 of this invention. It is a circuit diagram which shows the whole structure of Embodiment 4 of this invention. It is an operation | movement waveform diagram of Embodiment 4 of this invention. It is another operation | movement waveform diagram of Embodiment 4 of this invention. It is a circuit diagram which shows the whole structure of Embodiment 5 of this invention. It is explanatory drawing of the discrimination | determination operation | movement by the comparator of Embodiment 5 of this invention. It is explanatory drawing which shows the change of the lamp current and equivalent resistance of Embodiment 5 of this invention. It is a circuit diagram which shows the structure of the modification of Embodiment 5 of this invention. It is explanatory drawing of the detection operation by the structure of FIG. It is a circuit diagram which shows the whole structure of Embodiment 6 of this invention. It is an operation | movement waveform diagram of Embodiment 6 of this invention. It is a circuit diagram which shows the whole structure of Embodiment 7 of this invention. It is a circuit diagram which shows the structure of the modification of Embodiment 7 of this invention. It is an operation | movement waveform diagram of Embodiment 7 of this invention. It is a circuit diagram which shows the whole structure of Embodiment 8 of this invention. It is a circuit diagram which shows the whole structure of Embodiment 9 of this invention. It is an operation | movement waveform diagram of Embodiment 9 of this invention. It is a circuit diagram which shows the structure of the detection circuit of Embodiment 9 of this invention. It is a circuit diagram which shows the structure of the detection circuit of Embodiment 10 of this invention. It is an operation | movement waveform diagram of the comparative example with respect to Embodiment 10 of this invention. It is an operation | movement waveform diagram of Embodiment 10 of this invention. It is an operation | movement waveform diagram of Embodiment 11 of this invention. It is a circuit diagram which shows the whole structure of Embodiment 12 of this invention. It is an operation | movement waveform diagram of Embodiment 12 of this invention. It is a circuit diagram which shows the structure of the detection circuit of Embodiment 13 of this invention. It is an operation | movement waveform diagram of Embodiment 13 of this invention. It is a circuit diagram which shows the structure of the detection circuit of Embodiment 14 of this invention. It is an operation | movement waveform diagram of Embodiment 14 of this invention. It is an operation | movement waveform diagram of Embodiment 15 of this invention. It is another operation | movement waveform diagram of Embodiment 15 of this invention.

Explanation of symbols

La discharge lamp 1 voltage detection circuit 2 current detection circuit

Claims (16)

In a discharge lamp lighting device comprising an inverter circuit that turns on a discharge lamp as a light source by converting a DC voltage into a high-frequency AC voltage, the electrical characteristics of the output part or input part of the inverter circuit are detected, and when the discharge lamp is normally lit And an abnormal discharge detecting means for detecting a difference in electrical characteristics between when an abnormal discharge occurs due to incomplete connection of the inverter circuit output section, and the abnormal discharge detecting means detects the voltage at the output terminal of the inverter circuit. Discharge lamp lighting device. In a discharge lamp lighting device comprising an inverter circuit that turns on a discharge lamp as a light source by converting a DC voltage into a high-frequency AC voltage, the electrical characteristics of the output part or input part of the inverter circuit are detected, and when the discharge lamp is normally lit And an abnormal discharge detecting means for detecting a difference in electrical characteristics between when an abnormal discharge occurs due to an incomplete connection of the inverter circuit output section, and the abnormal discharge detecting means is connected in series with the discharge lamp and the current flowing through the discharge lamp A discharge lamp lighting device characterized by detecting a voltage of an element that limits the above. In a discharge lamp lighting device comprising an inverter circuit that turns on a discharge lamp as a light source by converting a DC voltage into a high-frequency AC voltage, the electrical characteristics of the output part or input part of the inverter circuit are detected, and when the discharge lamp is normally lit And an abnormal discharge detecting means for detecting a difference in electrical characteristics between when an abnormal discharge occurs due to an incomplete connection of the inverter circuit output unit, and the abnormal discharge detecting means detects the power consumption at the output terminal of the inverter circuit. A discharge lamp lighting device characterized. In a discharge lamp lighting device comprising an inverter circuit that turns on a discharge lamp as a light source by converting a DC voltage into a high-frequency AC voltage, the electrical characteristics of the output part or input part of the inverter circuit are detected, and when the discharge lamp is normally lit And an abnormal discharge detection means for detecting a difference in electrical characteristics between the occurrence of an abnormal discharge due to an incomplete connection of the inverter circuit output unit, and the abnormal discharge detection means includes a voltage at the output terminal of the inverter circuit and a current flowing through the discharge lamp. A discharge lamp lighting device characterized by calculating and detecting the impedance of a discharge lamp from the lamp. In a discharge lamp lighting device comprising an inverter circuit that turns on a discharge lamp as a light source by converting a DC voltage into a high-frequency AC voltage, the electrical characteristics of the output part or input part of the inverter circuit are detected, and when the discharge lamp is normally lit And an abnormal discharge detection means for detecting a difference in electrical characteristics between the occurrence of an abnormal discharge due to an incomplete connection of the inverter circuit output unit, and the abnormal discharge detection means includes a voltage at the output terminal of the inverter circuit and a current flowing through the discharge lamp. And a discharge lamp lighting device characterized in that it is detected by comparing with the above. In a discharge lamp lighting device comprising an inverter circuit that turns on a discharge lamp as a light source by converting a DC voltage into a high-frequency AC voltage, the electrical characteristics of the output part or input part of the inverter circuit are detected, and when the discharge lamp is normally lit And an abnormal discharge detection means for detecting a difference in electrical characteristics between when an abnormal discharge occurs due to incomplete connection of the inverter circuit output section, and the abnormal discharge detection means detects input power to the inverter circuit from a DC voltage. A discharge lamp lighting device characterized by. In a discharge lamp lighting device comprising an inverter circuit that turns on a discharge lamp as a light source by converting a DC voltage into a high-frequency AC voltage, the electrical characteristics of the output part or input part of the inverter circuit are detected, and when the discharge lamp is normally lit And an abnormal discharge detecting means for detecting a difference in electrical characteristics between occurrence of abnormal discharge due to incomplete connection of the inverter circuit output section, and the abnormal discharge detecting means detects an oscillation frequency of the inverter circuit. Discharge lamp lighting device. In a discharge lamp lighting device comprising an inverter circuit that turns on a discharge lamp as a light source by converting a DC voltage into a high-frequency AC voltage, the electrical characteristics of the output part or input part of the inverter circuit are detected, and when the discharge lamp is normally lit And an abnormal discharge detecting means for detecting a difference in electrical characteristics between when an abnormal discharge occurs due to incomplete connection of the inverter circuit output section, and the abnormal discharge detecting means is configured to detect a current flowing in the discharge lamp and a DC voltage to the inverter circuit. The discharge lamp lighting device is characterized in that it is detected by comparing with the input current. It has an inverter circuit that turns on a discharge lamp as a light source by converting a DC voltage into a high-frequency AC voltage, detects an electrical characteristic of the output part or input part of the inverter circuit, and when the discharge lamp is normally lit and an inverter circuit output part In the discharge lamp lighting device comprising an abnormal discharge detecting means for detecting a difference in electrical characteristics from the occurrence of abnormal discharge due to incomplete connection of the discharge lamp, the abnormal discharge detecting means has an electrical characteristic of the discharge lamp at the start of lighting of the discharge lamp. The discharge lamp lighting device according to claim 1, wherein a mask is provided so as not to detect until it is substantially stabilized. It has an inverter circuit that turns on a discharge lamp as a light source by converting a DC voltage into a high-frequency AC voltage, detects an electrical characteristic of the output part or input part of the inverter circuit, and when the discharge lamp is normally lit and an inverter circuit output part In a discharge lamp lighting device comprising an abnormal discharge detection means for detecting a difference in electrical characteristics from the occurrence of an abnormal discharge due to incomplete connection of the lamp, it is detected that the discharge lamp has started, and an error is detected in synchronization with the detection signal. The discharge lamp lighting device according to any one of claims 1 to 8, wherein a detection prevention signal is output. It has an inverter circuit that turns on a discharge lamp as a light source by converting a DC voltage into a high-frequency AC voltage, detects an electrical characteristic of the output part or input part of the inverter circuit, and when the discharge lamp is normally lit and an inverter circuit output part And a discharge lamp lighting device comprising an abnormal discharge detecting means for detecting a difference in electrical characteristics from the occurrence of abnormal discharge due to incomplete connection of the electrical characteristics, wherein the electric quantity of the electrical characteristics or the differential value of the envelope over time is predetermined. The discharge lamp lighting device according to any one of claims 1 to 8, wherein the operation of the abnormal discharge detecting means is started after detecting that the value is equal to or less than the value. It has an inverter circuit that turns on a discharge lamp as a light source by converting a DC voltage into a high-frequency AC voltage, detects an electrical characteristic of the output part or input part of the inverter circuit, and when the discharge lamp is normally lit and an inverter circuit output part In the discharge lamp lighting device comprising an abnormal discharge detection means for detecting a difference in electrical characteristics from the occurrence of abnormal discharge due to incomplete connection of the discharge lamp, the discharge lamp lighting device is capable of burst dimming, and at the time of burst dimming The discharge lamp lighting device according to claim 1, wherein a mask is provided so that the abnormal discharge detection means does not detect when the discharge lamp is started. It has an inverter circuit that turns on a discharge lamp as a light source by converting a DC voltage into a high-frequency AC voltage, detects an electrical characteristic of the output part or input part of the inverter circuit, and when the discharge lamp is normally lit and an inverter circuit output part In the discharge lamp lighting device comprising an abnormal discharge detection means for detecting a difference in electrical characteristics from the occurrence of abnormal discharge due to incomplete connection of the discharge lamp, the discharge lamp lighting device is capable of burst dimming, and the burst dimming signal The discharge lamp lighting device according to any one of claims 1 to 11, wherein a false detection prevention signal is output in synchronization. It has an inverter circuit that turns on a discharge lamp as a light source by converting a DC voltage into a high-frequency AC voltage, detects an electrical characteristic of the output part or input part of the inverter circuit, and when the discharge lamp is normally lit and an inverter circuit output part A discharge lamp lighting device comprising an abnormal discharge detection means for detecting a difference in electrical characteristics from the occurrence of an abnormal discharge due to incomplete connection of the discharge lamp. The discharge lamp lighting according to any one of claims 1 to 11, wherein a mask is provided so that the abnormal discharge detection means does not detect when switching to dimming or when switching from burst dimming to full lighting state. apparatus. It has an inverter circuit that turns on a discharge lamp as a light source by converting a DC voltage into a high-frequency AC voltage, detects an electrical characteristic of the output part or input part of the inverter circuit, and when the discharge lamp is normally lit and an inverter circuit output part A discharge lamp lighting device comprising an abnormal discharge detection means for detecting a difference in electrical characteristics from the occurrence of an abnormal discharge due to incomplete connection of the discharge lamp. The discharge lamp lighting device according to any one of claims 1 to 11, wherein a false detection prevention signal is output in synchronization with a signal when switching to dimming or switching from burst dimming to full lighting state. An emergency lighting fixture comprising the discharge lamp lighting device according to any one of claims 1 to 15.

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