JP2009076407A - Discharge lamp lighting device, illuminating device, and backlight device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To get rid of malfunction caused by variations of voltages of discharge lamps, to accurately detect lives of the discharge lamps, and to safely control lighting of the discharge lamps. <P>SOLUTION: When detectors VS1, VS2, and VS3 for detecting physical quantity (for example, voltage of a discharge lamp) of the discharge lamps La1, La2 and La3 are provided and output signals of the whole detectors VS1, VS2 and VS3 become input signals, lighting control of the discharge lamps La1, la2 and La3 is carried out on the basis of a reference signal Vref output from a calculator (adder ADD1 and amplifier AMP1) for outputting the reference signal based on a designated calculation method and outputs EN1, EN2 and EN3 of comparators CMP1, CMP2 and CMP3 for comparing the output signals of the detectors VS1, VS2 and VS3. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a discharge lamp lighting device, an illuminating device, and a backlight device capable of detecting the mounting and end of life of a discharge lamp.

  A discharge lamp is widely used in which an electron emitting substance (emitter) is applied to an electrode portion so that electrons are easily emitted into a discharge tube. For example, in a hot cathode fluorescent lamp (so-called fluorescent lamp), a filament is heated and an emitter applied to the filament emits thermoelectrons to light up. This type of discharge lamp has the advantage that by using an emitter, the loss of the electrode portion can be reduced even with a large discharge current, and the luminous efficiency of the discharge lamp can be improved. However, the emitter is consumed with the lighting time, and it becomes difficult for the electrodes to emit electrons, and the discharge becomes unstable. This is the life state of the discharge lamp using the emitter, and sooner or later the discharge lamp reaches this state.

  By the way, there is a problem in continuing lighting of the discharge lamp in this life state. This is because in the state where there is no electron emission from the emitter, the heat generation due to the electrode loss increases 10 times or more, and the temperature of the peripheral members of the discharge lamp rises. In addition, the stress on the lighting circuit is increased, and the temperature rise of the transformer and switching element is also increased. For this reason, various circuits for detecting the life of the discharge lamp have been devised.

  As a first conventional technique, in Patent Document 1 (Japanese Patent Publication No. 6-32313), a DC voltage at both ends of a fluorescent lamp that is lit at a high frequency is detected to detect a discharge lamp life. In the fluorescent lamp, when the filament electrode on one side reaches the end of its life, the life of the discharge lamp is detected by utilizing the rectification effect caused by the half-wave discharge. That is, when the electrode side where the emitter is still left becomes a negative potential, electrons are emitted from the electrode and the discharge lamp current flows normally, but when the potential of the electrode side where the emitter is consumed becomes a negative potential, Since no electrons are emitted from the lamp, the discharge lamp current is reduced. As a result, an imbalance occurs between the positive and negative discharge lamp currents. This appears as a DC voltage across the discharge lamp. The lifetime is detected by comparing the DC voltage with a predetermined reference value.

  As the second conventional technique, in Patent Document 2 (Japanese Patent Laid-Open No. 2001-35679), unlike the first conventional technique, the peak value of the voltage applied to the fluorescent lamp is detected to detect the discharge lamp life. Generally, the voltage of the discharge lamp is considered as the sum of the cathode fall voltage and the positive column voltage. When the emitter used for the discharge lamp electrode is activated, the cathode fall voltage is about 10V. Since the voltage when the fluorescent lamp is turned on is about 100 to 150 V, the cathode fall voltage is negligible. However, when the emitter of the electrode is consumed and electrons cannot be emitted, the cathode fall voltage rises to 100V or higher. This voltage increase occurs in a high frequency half cycle in the life state of the electrode emitter on one side, and occurs in both high frequency cycles in the life state of the electrode emitters on both sides.

As a general voltage detection method, there is a full-wave rectification (peak detection) using a diode. However, in the life state of the electrode emitter on one side, the discharge lamp voltage only rises by about 50 V, so that accurate life judgment is difficult. In this prior art, a detecting means for determining a lifetime peak voltage value is provided in each of the high-frequency positive and negative cycles, and the lifetime of the electrode emitter on one side or both sides is detected. Therefore, there is a feature that the life can be easily detected even in the life state of the electrode emitter on one side.
Japanese Examined Patent Publication No. 6-32313 JP 2001-35679 A

  In the first prior art, since the DC voltage due to the rectifying action during half-wave discharge is detected, the life state of the electrode emitter on one side can be detected, but the life state of the electrode emitters on both sides cannot be detected. That is, when the electrode emitters on both sides are in a life state, the discharge lamp current changes, but no positive / negative current imbalance occurs, and therefore no DC voltage appears across the discharge lamp. Therefore, in order to detect the life state of the electrode emitters on both sides, there is a drawback that another life detecting means is required.

  Another problem is that the detection delay time is large. In order to obtain a DC voltage detection signal by smoothing the high-frequency voltage across the discharge lamp, a low-pass filter with a large attenuation is required. In such a low-pass filter, since the time constant is large, the rise of the detection signal is delayed. Therefore, for example, it is difficult to detect the life of the discharge lamp in a dimming state by intermittent lighting of the discharge lamp such as burst dimming used in the backlight device. In addition, the DC voltage component at both ends of the discharge lamp may be generated due to an imbalance in the switching time of the inverter circuit, and there is a problem that it is difficult to set a threshold value for a DC voltage detection signal.

  In the second prior art, malfunction due to variations in the discharge lamp voltage is likely to occur, and circuit design is difficult. There are three factors that cause variations in the discharge lamp voltage.

  One is voltage fluctuation due to variation in internal gas pressure of each discharge lamp. This is a variation in the discharge lamp voltage due to the pressure of the rare gas inside the discharge lamp, and generally exists at about ± 10%.

  The other is voltage fluctuation due to ambient temperature change of the discharge lamp. When the surroundings of the discharge lamp are in a low temperature state, the voltage drop of the discharge lamp is about 40% lower than that at room temperature. In addition, a decrease of about 20% at room temperature occurs even at high temperatures.

  The other is voltage fluctuation due to the dimming state of the discharge lamp. Dimming reduces the discharge lamp current and increases the discharge lamp voltage. Although it depends on the dimming level, a voltage fluctuation of about 40% occurs.

  The above three voltage fluctuations are particularly noticeable in a discharge lamp having a thin and long discharge tube. That is, a thin and long discharge lamp has a high discharge lamp voltage, but since this voltage rise is the voltage of the discharge tube positive column, the amount of voltage change due to internal gas pressure, ambient temperature, and dimming is large.

  In the second prior art, the discharge lamp life detection needs to be designed in consideration of these discharge lamp voltage fluctuations. However, in the case of a discharge lamp having a thin and long discharge tube, that is, the discharge lamp voltage is high. Design becomes difficult with a discharge lamp. In such a case, it is necessary to increase the accuracy of the temperature characteristics of the detection circuit itself, and there is a problem that the cost of components increases.

  The present invention has been made in view of the above points, and it is an object of the present invention to eliminate malfunction due to voltage variation of the discharge lamp, to accurately detect the life, and to control lighting of the discharge lamp safely. It is another object of the present invention to provide a discharge lamp lighting device that solves the above problems at low cost in a circuit that controls lighting of a plurality of discharge lamps at once.

  In order to solve the above-mentioned problem, the invention of claim 1 includes impedances Z1, Z2, Z3 for connecting the discharge lamps La1, La2, La3 to the power source PS1 and the discharge lamps La1, La2 as shown in FIG. , La3, a discharge lamp lighting device having detectors VS1, VS2, VS3 for detecting a physical quantity (for example, discharge lamp voltage), comprising a plurality of discharge lamps La1, La2, La3 and detectors VS1, VS2, VS3. The detectors VS1, VS2, and VS3 output signals as inputs, and a calculator (adder ADD1 and amplifier AMP1) that outputs a reference signal based on a predetermined calculation method, and a reference signal Vref output from the calculator. And at least one comparator CMP1, CMP2, CMP3 for comparing the output signals of the detectors VS1, VS2, VS3, and the comparator CMP1 CMP2, the output EN1, EN2, EN3 of CMP3 is characterized in that for performing lighting control of the discharge lamp La1, La2, La3.

  According to a second aspect of the invention, in the first aspect of the invention, the calculation method of the arithmetic unit is characterized in that an arithmetic average value of input values is used as a calculation result, as shown in FIGS.

  According to a third aspect of the present invention, in the first aspect of the present invention, as shown in FIG. 6, the arithmetic method of the arithmetic unit uses the minimum input value (f = MIN) as the arithmetic result.

  According to a fourth aspect of the present invention, in the first aspect of the invention, the discharge lamps La1, La2, La3 and the detectors VS1, VS2, VS3 are three or more, and the calculation method of the calculator is as shown in FIG. The median value (f = MEDIAN) of the input values is used as the calculation result.

  According to a fifth aspect of the present invention, in the first aspect of the invention, the discharge lamps La1, La2, La3 and the detectors VS1, VS2, VS3 are three or more, and the calculation method of the calculator is as shown in FIG. The arithmetic result is a value obtained by arithmetically averaging values other than the maximum value of the input values.

  According to a sixth aspect of the present invention, in the first aspect of the present invention, as shown in FIG. 14, the second comparators CMP11, CMP21 for comparing the output signals of the detectors VS1, VS2, VS3 with the second reference signal Vref2. , CMP31 and at least one of the discharge lamps La1, La2, La3 according to the logical sum of the output signals of the comparators CMP1, CMP2, CMP3 and the output signals of the second comparators CMP11, CMP21, CMP31. Lighting control is performed.

  According to a seventh aspect of the present invention, in any one of the first to sixth aspects, as shown in FIGS. 8, 9, and 16, a predetermined correction value (correction signal Arv or detection signal) is added to the reference signal of the computing unit f. Means for adding a margin ΔVs) (adder ADD3 or the like) is provided.

  According to an eighth aspect of the present invention, in any one of the first to sixth aspects, as shown in FIG. 16, means for subtracting a predetermined correction value (ΔVs) from the reference signal of the computing unit f (subtracter SUB1) It is characterized by having.

  A ninth aspect of the invention is characterized in that, in any one of the first to eighth aspects of the invention, the lighting control of the discharge lamps La1 to La3 is to suppress or turn off the output of at least one lamp.

  A tenth aspect of the present invention is the calculation method according to any one of the first to ninth aspects, wherein the computing unit f is operated according to at least one output of the comparators CMP1, CMP2, and CMP3 as shown in FIG. It is characterized by changing.

  According to an eleventh aspect of the invention, in any one of the first to tenth aspects, as shown in FIG. 13, the discharge lamps La1, La2, La3 are connected via at least one connector CON1, CON2, CON3. It is characterized by that.

  A twelfth aspect of the present invention is an illumination device including the discharge lamp lighting device according to any one of the first to eleventh aspects.

  The invention of claim 13 is a backlight device comprising the discharge lamp lighting device according to any one of claims 1 to 11 (FIG. 21).

  According to the first aspect of the present invention, since the reference signal for life detection is created by calculating the detection signals obtained from the plurality of discharge lamps, the malfunction due to the variation of the discharge lamps is eliminated, and the life is accurate. Detection can be performed. That is, even if the amount of the discharge lamp varies greatly depending on the ambient temperature and lighting time of the discharge lamp, the life discharge lamp can be easily identified. In particular, as the number of discharge lamps increases, the reference signal for comparison becomes more stable, and the life can be detected with higher accuracy. Therefore, it is useful for a discharge lamp lighting device that lights many discharge lamps having a high voltage.

  According to the invention of claim 2, since the arithmetic mean value is used as the calculation result, the calculator can be configured with only a simple adder and a coefficient amplifier, and without using a microcomputer or the like, There is an advantage that it can be configured inexpensively using an operational amplifier or the like.

  According to the invention of claim 3, since the minimum value of the input value is the calculation result, when detecting the discharge lamp life of three lamps, the average value signal is the abnormal input signal when two lamps are abnormal simultaneously. It is possible to prevent the reference signal from rising due to the influence of. Therefore, even when the number of discharge lamps is small, it is possible to provide a safe discharge lamp lighting device that reliably detects the discharge lamp life and controls lighting.

  According to the invention of claim 4, since the median value of the input values is the calculation result, compared to the method using the arithmetic average, when detecting the life of the discharge lamp of three or more lamps, one lamp abnormal It is possible to prevent the reference signal from being raised or lowered due to the influence of the abnormal value of the average value signal. Therefore, even when the number of discharge lamps is small, it is possible to provide a safe discharge lamp lighting device that reliably detects the discharge lamp life and controls lighting. In addition, the method using the median is a calculation method in which the input values are arranged in order of magnitude, and the value located at the center is used as a reference value for abnormality determination. It is particularly useful in a discharge lamp lighting device to be performed.

  According to the invention of claim 5, since the arithmetic result is a value obtained by arithmetically averaging values other than the maximum value of the input, when detecting the life of three or more discharge lamps, when one lamp is abnormal It is possible to prevent the reference signal from rising due to the average value signal being affected by the abnormal input signal. Moreover, since the average characteristic close to the arithmetic mean method is obtained, there is an advantage that the calculated value is stable when the number of discharge lamps is large.

  According to the sixth aspect of the invention, since the second comparator for comparing the output signal of the detector with the second reference signal is used in combination, all the discharge lamps are abnormal at the same time. Even so, it can be determined that there is an abnormality based on the comparison result with the second reference signal.

  According to the seventh aspect of the present invention, since it has means for adding a predetermined correction value to the reference signal of the arithmetic unit, for example, the correction value at the beginning of lighting is increased, and the correction value is set as the lighting time elapses. By making it smaller, it is possible to reliably perform detection at the life time after long-term lighting while preventing erroneous detection of the life at the beginning of lighting with large variations in the discharge lamp voltage and the like.

  According to the eighth aspect of the present invention, since the apparatus has means for subtracting a predetermined correction value from the reference signal of the arithmetic unit, the discharge lamp is short-circuited as an abnormality detection on the side where the discharge lamp voltage decreases, for example. Or when it becomes a ground fault state, it can detect as a discharge lamp abnormality. In addition, when detecting the discharge lamp current instead of the discharge lamp voltage, if the detection margin is subtracted as a predetermined correction value from the reference signal of the arithmetic unit, the discharge lamp current decreases due to the increase of the discharge lamp voltage. Can be detected as an abnormal discharge lamp.

  According to the invention of claim 9, since the lighting control of the discharge lamp is set to suppress or turn off the output of at least one lamp, other normal discharge lamps can continue to be lit and improve the convenience for the user. it can.

  According to the invention of claim 10, when the output of the abnormal discharge lamp is suppressed or extinguished, the calculation formula of the reference signal is changed, so that it is possible to accurately detect the life of other normal discharge lamps. it can.

  According to the eleventh aspect of the present invention, it is possible to detect a voltage increase during loose contact of the connector as an abnormality of the discharge lamp.

  According to the inventions of claims 12 and 13, it is possible to provide an illumination device and a backlight device having the effects of claims 1 to 11.

(Basic configuration)
FIG. 1 is a circuit diagram showing a basic configuration of the present invention. Hereinafter, the circuit configuration will be described. The AC input terminal of the full-wave rectifier DB is connected to the commercial AC power source Vin. A power factor correction circuit PFC is connected to the DC output terminal of the full-wave rectifier DB. The power factor correction circuit PFC includes a step-up chopper circuit, and the smoothing capacitor on the output side is charged with a DC voltage boosted from the peak voltage of the pulsating voltage that is full-wave rectified by the full-wave rectifier DB. The oscillator OSC4 improves the input power factor by controlling the switching element of the step-up chopper circuit at a high frequency so that the average value of the input current from the commercial AC power source Vin is similar to the input voltage. ing.

  A plurality of inverter circuits INV1, INV2, and INV3 are connected in parallel to the smoothing capacitor on the output side of the power factor correction circuit PFC. Each inverter circuit forms a half-bridge circuit by a series circuit of a pair of switching elements that are alternately turned on and off, and a resonance inductor and a coupling capacitor are connected between the connection point of the switching element and the ground. A series circuit of resonance capacitors is connected. The resonance capacitor also serves as a filament preheating capacitor for the discharge lamps La1, La2, and La3. Oscillators OSC1, OSC2, and OSC3 alternately turn on and off the switching elements of the inverter circuits INV1, INV2, and INV3 to perform preheating, starting, lighting, and dimming operations of the discharge lamps La1, La2, and La3. To control.

  One end of the discharge lamp La1 connected to the high-frequency output end of the inverter circuit INV1 is connected to the ground (the negative electrode of the power factor correction circuit PFC), and the other end (non-ground side end) of the discharge lamp La1 is a voltage detector. VS1 is connected.

  The voltage detector VS1 includes operational amplifiers A1 and A2. The voltage detector VS1 inputs a high-frequency voltage at the electrode terminal on the non-ground side of the discharge lamp La1, and outputs a signal subjected to full-wave rectification and smoothing.

  The voltage detectors VS2 and VS3 having the same configuration are also connected to the non-ground side ends of the discharge lamps La2 and La3 connected to the high frequency output ends of the other inverter circuits INV2 and INV3. Although not shown, the voltage detector VS2 includes operational amplifiers A3 and A4, and the voltage detector VS3 includes operational amplifiers A5 and A6, and has the same circuit configuration as the voltage detector VS1. Suppose you are.

  Next, the configuration of the signal processing circuit for the detection signals of the voltage detectors VS1, VS2, and VS3 will be described. The detection signals of the detectors VS1, VS2, and VS3 are applied to the + side input terminals of the comparators CMP1, CMP2, and CMP3, and are compared with the reference voltage Vref of the − side input terminal. When the detection signal at the + side input terminal of any comparator CMPi (i = 1, 2, 3) becomes higher than the reference voltage Vref at the − side input terminal, the output terminal ENi of the comparator CMPi becomes High level, The signal is transmitted as an oscillation stop signal or an output suppression signal to the oscillator OSCi of the corresponding inverter circuit INVi.

  As described above, the detection signal has a large amount of voltage change due to the internal gas pressure of the discharge lamp, the ambient temperature, and dimming. Further, the level of the detection signal varies depending on variations in circuit constants of the inverter circuit and temperature characteristics of the detector itself. Therefore, it is difficult to set the reference voltage Vref of the negative input terminal of the comparator CMPi.

  In the present invention, each detection signal is added by the adder ADD1, and the added signal is multiplied by 1/3 by the amplifier AMP1, thereby obtaining an arithmetic average of each detection signal, and the value of the arithmetic average. + Α (α is a detection margin) is adopted as the reference voltage Vref.

  More specifically, the adder ADD1 includes an operational amplifier A7 whose non-inverting input terminal is connected to the ground level. Detection signals of the voltage detectors VS1, VS2, and VS3 are input to the inverting input terminal of the operational amplifier A7 through the input resistors Ra1, Ra2, and Ra3, respectively. A feedback resistor Rf1 is connected between the output terminal and the inverting input terminal of the operational amplifier A7. Since the amplification factor of the operational amplifier A7 is extremely high, the potential of the inverting input terminal is substantially the same potential (virtual short circuit state) as that of the non-inverting input terminal. Since the input impedance of the operational amplifier A7 is extremely high, all input currents flowing from the output terminals of the voltage detectors VS1, VS2, and VS3 through the input resistors Ra1, Ra2, and Ra3 are all output from the operational amplifier A7 through the feedback resistor Rf1. If the resistance values of the input resistors Ra1, Ra2, Ra3 and the feedback resistor Rf1 are the same, the detection signals of the voltage detectors VS1, VS2, VS3 are added to the output terminal of the adder ADD1. Thus, an inverted and amplified signal is obtained.

  Next, the output signal of the adder ADD1 is inverted and amplified at a predetermined ratio by the amplifier AMP1. The amplifier AMP1 includes an operational amplifier A8, and its non-inverting input terminal is connected to the ground level. The output terminal of the adder ADD1 is connected to the inverting input terminal of the operational amplifier A8 via the input resistor Ri2. A feedback resistor Rf2 is connected between the output terminal and the inverting input terminal of the operational amplifier A8. Since the amplification factor of the operational amplifier A8 is extremely high, the potential of the inverting input terminal is substantially the same potential (virtual short circuit state) as the non-inverting input terminal. Since the input impedance of the operational amplifier A8 is extremely high, all the input current that flows to the output terminal of the adder ADD1 through the input resistor Ri1 flows from the output terminal of the operational amplifier A8 through the feedback resistor Rf2, and the input resistor Ri2 Assuming that the ratio of the resistance value of the feedback resistor Rf2 is A: 1, a signal obtained by inverting and amplifying the output signal of the adder ADD1 at a predetermined ratio (−1 / A times) is obtained at the output terminal of the amplifier AMP1. Will be. Therefore, the reference voltage Vref obtained at the output terminal of the amplifier AMP1 is an arithmetic average value of the detection signals of the voltage detectors VS1, VS2, and VS3.

  It should be noted that the reference voltage Vref is set to each voltage detector by adjusting the amplification factor (1 / A) of the amplifier AMP1 to be slightly larger than 1/3 (for example, about 1 / A = 0.37). The arithmetic average value of the detection signals of VS1, VS2, and VS3 is set to + α (α is a detection margin), and one of the detection signals is increased so as to protrude from the other two detection signals. In the case, it can be determined that an abnormality has occurred.

  Here, the arithmetic mean is used for setting the reference voltage Vref. However, as will be described in each embodiment described later, a median value (MEDIAN), a minimum value, or a maximum value (that is, an abnormal value) is used. It is possible to use an average value excluding the signal) and various variations.

  Hereinafter, various embodiments relating to the setting of the reference voltage Vref will be described.

(Embodiment 1)
FIG. 2 shows a circuit diagram of the first embodiment. In the present embodiment, there is a configuration in which three discharge lamp lighting circuits are connected in parallel to the output of one high-frequency voltage source PS1. The first discharge lamp lighting circuit is a series circuit of impedance Z1 and discharge lamp La1, the second discharge lamp lighting circuit is a series circuit of impedance Z2 and discharge lamp La2, and the third discharge lamp lighting circuit is impedance Z3. And a discharge lamp La3 in series. One electrode end of each of the discharge lamps La1 to La3 is grounded. In addition, detectors VS1 to VS3 are provided which input high-frequency voltages at the electrode ends on the non-ground side of the discharge lamps La1 to La3 and output a signal subjected to full-wave rectification and smoothing. Further, an adder ADD1 for adding all the outputs of the detectors VS1 to VS3 and an amplifier AMP1 for amplifying the output of the adder are provided. Further, three comparators CMP1 to CMP3 for comparing the outputs of the detectors VS1 to VS3 and the reference voltage Vref which is the output of the amplifier AMP1 are provided.

  Hereinafter, the operation of this embodiment will be described. It is assumed that the discharge lamps La1 to La3 are lit by the high frequency voltage source PS1. The impedances Z1 to Z3 are elements (ballasts) for stabilizing the lighting currents of the discharge lamps La1 to La3. The detector VS1 is a circuit that performs full-wave rectification and smoothing of the non-ground side voltage of the discharge lamp La1. The high voltage of the discharge lamp La1 is divided and full-wave rectified by the operational amplifiers A1 and A2. Further, a circuit for smoothing by an integrating capacitor by the operational amplifier A2 is also provided. An adder ADD1 that adds the outputs of the detectors VS1 to VS3 is an adder using an operational amplifier A7. The outputs of all the detectors VS1 to VS3 are input via resistors Ra1 to Ra3. Further, the output of the adder ADD1 is amplified by the inverting amplifier AMP1, and the polarity of the output voltage of the adder ADD1 is inverted. Since the output of the adder ADD1 has a voltage amplitude that is three times that of the outputs of the detectors VS1 to VS3, it is amplified to about 1/3 times by the inverting amplifier AMP1 and is almost equal to the output signal of the detectors VS1 to VS3 It is attenuated. The adder ADD1 and the inverting amplifier AMP1 constitute an average value calculator. The calculation method of the average value calculator is an arithmetic mean method. The output of the amplifier AMP1 is input as the reference voltage Vref to the negative side input terminals of the comparators CMP1 to CMP3. The outputs of the detectors VS1 to VS3 are input to the + side input terminals of the comparators CMP1 to CMP3, respectively. For example, when the voltage at the + side input terminal of the comparator CMP1 is higher than the reference voltage Vref, the output EN1 of the comparator CMP1 becomes High, and the corresponding discharge lamp La1 is determined to have a lifetime.

  Next, an example of the detection operation is shown. FIG. 3 shows the detection operation when the discharge lamp La1 has reached the one-side life. The detector VS1 is a constant that sets the discharge lamp voltage to 1/100. When the discharge lamp La1 is a one-side life discharge lamp, the discharge lamp voltage is 260V, and the discharge lamps La2 and La3 are normal discharge lamp voltages 200V, the detector voltages are VS1 = 2.6 and VS2 = 2.0, respectively. , VS3 = 2.0. The detector signals are added by an adder ADD1, and attenuated 0.37 times by an amplifier AMP1. The 0.37 times is a constant obtained by giving a detection margin of about 10% to one third (0.33).

  The value output by the adder ADD1 is 6.6, but this is attenuated by the amplifier AMP1, and the reference voltage Vref becomes 2.44. This reference voltage Vref is input to the negative input terminal of the comparator CMP1. The signal of the detector VS1 is input to the + side input terminal of the comparator CMP1. In the comparator CMP1, since the signal level of the + side input terminal (VS1 = 2.6) is higher than that of the − side input terminal (Vref = 2.44), the output EN1 of the comparator CMP1 becomes High, and the life of the discharge lamp La1. Is detected.

  Next, a detection example in the case where the discharge lamp voltage fluctuates due to factors such as ambient temperature in the same discharge lamp will be described. FIG. 4 shows a detection operation when the discharge lamp La1 has a one-side life in a high-temperature environment. When the discharge lamp La1 is a one-side life discharge lamp, the discharge lamp voltage is 220V, and the discharge lamps La2 and La3 are normal discharge lamp voltages 160V, the detector voltages are VS1 = 2.2 and VS2 = 1.6, respectively. , VS3 = 1.6. The value output by the adder ADD1 is 5.4, but this is attenuated by the amplifier AMP1, and the reference voltage Vref becomes 2.0. In the comparator CMP1, since the signal level of the + side input terminal (VS1 = 2.2) is higher than that of the − side input terminal (Vref = 2.0), the output EN1 of the comparator CMP1 becomes High and the life of the discharge lamp La1. Is detected.

  When the life is detected, control is performed to turn off all the discharge lamps La1 to La3.

  The present invention is characterized in that the reference voltage of the comparator is set according to the discharge lamp voltage as described above. Therefore, in the present invention, even when the absolute voltage value of the discharge lamp varies greatly depending on the ambient temperature and lighting time of the discharge lamp, the life discharge lamp can be easily identified. In this embodiment, the number of lamps is three, but as the number of discharge lamps increases, the comparison reference voltage value becomes stable, and the life can be detected with higher accuracy. Therefore, it is useful for a discharge lamp lighting device that lights many discharge lamps having a high voltage.

  In this embodiment, the detector that detects the state of the discharge lamp detects a high-frequency discharge lamp voltage, but in addition, the temperature near the discharge lamp electrode, the DC voltage applied to the discharge lamp, and the output from the discharge lamp Even if it is light (visible light, infrared light, ultraviolet light), discharge lamp current, etc., the lifetime can be detected without malfunction due to characteristic fluctuations of the discharge lamp.

  The discharge lamp for detecting the lifetime may be a discharge lamp using an emitter as an electrode, and can be detected well with a hot cathode fluorescent lamp, a semi-hot discharge lamp, an HID lamp, or the like.

  Further, the power source of the discharge lamp is not limited to the high frequency, and the life can be detected satisfactorily by direct current lighting and low frequency lighting. The operation at the time of detecting the life discharge lamp may not only turn off all the discharge lamps, but also turn off only the discharge lamp whose life has been detected, or reduce the discharge lamp output.

  By using the present invention, it is possible to provide a safe discharge lamp lighting device that reliably detects the life of a discharge lamp and controls lighting.

(Embodiment 2)
FIG. 5 shows a main configuration of the second embodiment of the present invention. This embodiment is different from the previous embodiment in the calculation method of the calculator, and is characterized in that the median method is used for the calculation of the calculator f. In the figure, detectors VS1 to VS3 that detect the discharge lamp voltage, a calculator f that calculates a reference voltage Vref from the detection signal, and an output of the detector VS1 is a + side input, which is an output of the calculator f. A comparator CMP1 that compares the reference voltage Vref as a negative input is shown. The comparators CMP2 and CMP3 that compare the outputs of the other detectors VS2 and VS3 with the reference voltage Vref are not shown.

  The operation of this embodiment will be described below. As outputs of the detectors, VS1 = 2.6, VS2 = 2.1, and VS3 = 2.0 are input to the calculator f. The calculator f performs a calculation for obtaining a median value of these values. The median is an arithmetic method in which input values are arranged in order of magnitude and a value located at the center is the result. That is, when there is an input in the order of VS1> VS2> VS3, the calculation result is a value VS2 = 2.1 located at the center. The calculation result is input to the comparator CMP1 as the reference voltage Vref. In the comparator CMP1, since the signal at the + side input terminal (VS1 = 2.6) is larger than the signal at the − side input terminal (Vref = 2.1), the output EN1 becomes High and the life is detected.

  Here, a detection margin of about 10% may be given to the output of the arithmetic unit f for obtaining the median value. This is because it is rare that the detection voltages of the three discharge lamps are completely the same, and if there is no detection margin, the median value and the maximum value are always different. It is. Therefore, the detection margin may be set larger than the fluctuation range that can occur in a normal state, and when the difference between the median and the maximum value is large enough to exceed the detection margin, it may be determined that an abnormality has occurred. .

  If this method is used, compared with the method using the arithmetic average of the first embodiment, when detecting the life of three or more discharge lamps, the average value signal is affected by the abnormal input signal when one lamp is abnormal. Thus, the reference signal can be prevented from rising or falling. In addition, this method is a calculation method in which input values are arranged in order of magnitude, and the value located at the center (+ detection margin) is used as a reference value for abnormality determination. This is particularly useful in a discharge lamp lighting device that performs the above.

  By using this embodiment, it is possible to provide a safe discharge lamp lighting device that reliably detects the life of a discharge lamp and controls lighting even when the number of discharge lamps is small.

(Embodiment 3)
FIG. 6 shows a main configuration of the third embodiment of the present invention. This embodiment is different from the previous embodiment in the calculation method of the calculator, and is characterized in that the minimum value method is used for the calculation of the calculator f. In the figure, detectors VS1 to VS3 that detect the discharge lamp voltage, a calculator f that calculates a reference voltage Vref from the detection signal, and an output of the detector VS1 is a + side input, which is an output of the calculator f. A comparator CMP1 that compares the reference voltage Vref as a negative input is shown. The comparators CMP2 and CMP3 that compare the outputs of the other detectors VS2 and VS3 with the reference voltage Vref are not shown.

  The operation of this embodiment will be described below. As outputs of the detectors, VS1 = 2.6, VS2 = 2.1, and VS3 = 2.0 are input to the calculator f. The calculator f performs a calculation for obtaining the minimum value of these values. That is, when there is an input in the order of VS1> VS2> VS3, the calculation result is the minimum value VS3 = 2.0. The calculation result is input to the comparator CMP1.

  In the comparator CMP1, since the signal at the + side input terminal (VS1 = 2.6) is larger than the signal at the − side input terminal (Vref = 2.0), the output EN1 becomes High and the life is detected.

  Here, a detection margin of about 10% may be given to the output of the arithmetic unit f for obtaining the minimum value. This is because if there is no detection margin at all, the detection value is always larger than the minimum value. Therefore, a detection margin may be set larger than a fluctuation range that can occur in a normal state, and when the difference between the minimum value and the detection value is large enough to exceed the detection margin, it may be determined that an abnormality has occurred. .

  If this method is used, when the discharge lamp life of three lamps is detected, it is possible to prevent the reference signal from rising due to the influence of the abnormal value of the average signal when two lamps are abnormal simultaneously. .

  By using this embodiment, it is possible to provide a safe discharge lamp lighting device that reliably detects the life of a discharge lamp and controls lighting even when the number of discharge lamps is small.

(Embodiment 4)
FIG. 7 shows a main configuration of the fourth embodiment of the present invention. This embodiment is different from the previous embodiment in the calculation method of the calculator, and is characterized in that the average value excluding the maximum value is used for the calculation of the calculator f. In the figure, detectors VS1 to VS3 that detect the discharge lamp voltage, a calculator f that calculates a reference voltage Vref from the detection signal, and an output of the detector VS1 is a + side input, which is an output of the calculator f. A comparator CMP1 that compares the reference voltage Vref as a negative input is shown. The comparators CMP2 and CMP3 that compare the outputs of the other detectors VS2 and VS3 with the reference voltage Vref are not shown.

  The operation of this embodiment will be described below. As outputs of the detectors, VS1 = 2.6, VS2 = 2.1, and VS3 = 2.0 are input to the calculator f. The calculator f performs an operation for obtaining an average value obtained by removing the maximum value from these values. That is, when there is an input in the order of VS1> VS2> VS3, the calculation result is an average value (VS2 + VS3) /2=2.05 excluding the maximum value VS1. The calculation result is input to the comparator CMP1.

  In the comparator CMP1, since the signal at the + side input terminal (VS1 = 2.6) is larger than the signal at the − side input terminal (Vref = 2.05), the output EN1 becomes High and the life is detected.

  Here, a detection margin of about 10% may be given to the output of the arithmetic unit f for obtaining the average value excluding the maximum value. For example, if the detection margin is set to be larger than the fluctuation range that can occur in a normal state, and the difference between the average value excluding the maximum value and the maximum value exceeds the detection margin, What is necessary is just to determine with generation | occurrence | production.

  Using this technique, when detecting the life of three or more discharge lamps, it is possible to prevent the reference signal from rising due to the influence of the abnormal input signal on the average value signal when one lamp is abnormal. .

  Moreover, since the average characteristic close to the arithmetic mean method is obtained, there is an advantage that the calculated value is stable when the number of discharge lamps is large.

  By using this embodiment, it is possible to provide a safe discharge lamp lighting device that reliably detects the life of the discharge lamp and controls the lighting.

(Embodiment 5)
FIG. 8 shows the main configuration of the fifth embodiment of the present invention. The present embodiment is characterized in that an adder ADD3 for adding the correction signal Arv to the output of the arithmetic unit f is added to any one of the first to fourth embodiments. The correction signal Arv is changed with the lighting elapsed time. The figure shows detectors VS1 to VS3 for detecting the discharge lamp voltage, an arithmetic unit f for calculating a reference voltage Vref from the detection signal, an adder ADD3 for adding a correction signal Arv to the output of the arithmetic unit f, and an addition A comparator CMP1 is shown that compares the reference voltage Vref, which is the output of the comparator ADD3, with the-side input and the output of the detector VS1 with the + side input. The comparators CMP2 and CMP3 that compare the outputs of the other detectors VS2 and VS3 with the reference voltage Vref are not shown.

  The present embodiment is characterized in that a correction signal is added to the calculation result of the calculator f. Further, the correction signal is set according to the lighting elapsed time or the like. The discharge lamp may contain a small amount of impure gas such as nitrogen, carbon dioxide, or hydrogen in the discharge tube at the beginning of lighting. As the lighting time elapses, the impure gas tends to be adsorbed by phosphors in the discharge lamp. As a result, the discharge lamp voltage may gradually decrease. However, since the concentration of the impurity gas in the initial stage varies depending on the discharge lamp, the variation in the discharge lamp voltage at the beginning of lighting tends to be larger than the variation in the discharge lamp voltage after long-term lighting. Therefore, by increasing the correction signal Arv at the beginning of lighting and reducing the correction signal Arv as the lighting time elapses, it is possible to prevent erroneous detection of the life at the beginning of lighting and to reliably perform detection at the life time. .

  By using this embodiment, it is possible to provide a safe discharge lamp lighting device that reliably detects the life of a discharge lamp and controls lighting even during long-term use.

(Embodiment 6)
FIG. 9 shows the main configuration of Embodiment 6 of the present invention. This embodiment is characterized in that adders ADD11 to ADD13 for adding correction signals Arv1 to Arv3 are added to the output of the arithmetic unit f in any of the first to fourth embodiments. The figure shows detectors VS1 to VS3 for detecting the discharge lamp voltage, a calculator f for inputting the outputs of the detectors VS1 to VS3, an adder ADD11 for adding the output of the calculator f and the correction signal Arv1, and a calculation. An adder ADD12 for adding the output of the calculator f and the correction signal Arv2, an adder ADD13 for adding the output of the calculator f and the correction signal Arv3, and the output of the detector VS1 as the + side input, and the output of the adder ADD11 being The comparator CMP1 for comparison as the negative side input and the output of the detector VS2 are set as the positive side input, the comparator CMP2 for comparing the output of the adder ADD12 as the negative side input and the output of the detector VS3 as the positive side input, A comparator CMP3 that compares the output of the adder ADD13 as a negative input is shown.

  The present embodiment is characterized in that correction signals Arv1, Arv2, and Arv3 that are adapted to the respective use states of the discharge lamps are added to the reference signals of the comparators CMP1, CMP2, and CMP3 that determine the life of the discharge lamp. When many discharge lamps are lit, the ambient temperature of the discharge lamp may not be constant. According to this temperature difference, the discharge lamp voltage is unevenly distributed. By adding a correction value of the discharge lamp voltage that matches the temperature distribution in advance to the reference value of the comparator, the life detection accuracy of the discharge lamp can be improved. The correction signals Arv1 to Arv3 may use values obtained by actual temperatures, but may be changed during the lighting of the discharge lamp. In particular, the time during which the discharge lamp characteristics stabilize with the lighting time may be obtained in advance, and the correction signals Arv1 to Arv3 may be set during the lighting at that time.

  By using this embodiment, it is possible to provide a safe discharge lamp lighting device that reliably detects the life of a discharge lamp and controls lighting even during long-term use.

(Embodiment 7)
FIG. 10 shows a main configuration of Embodiment 7 of the present invention. This embodiment is characterized in that adders ADD21 to ADD23 for adding the correction signals Asv1 to Asv3 to the outputs of the detectors VS1 to VS3 are added in any of the first to fourth embodiments. The figure shows detectors VS1 to VS3 for detecting the discharge lamp voltage, an adder ADD21 for adding the output of the detector VS1 and the correction signal Asv1, and an adder ADD22 for adding the output of the detector VS2 and the correction signal Asv2. The adder ADD23 for adding the output of the detector VS3 and the correction signal Asv3, the arithmetic unit f for inputting the outputs of the adders ADD21 to ADD23, the output of the adder ADD21 as the + side input, and the output of the arithmetic unit f The comparator CMP1 to be compared as the negative side input and the output of the adder ADD22 as the positive side input, the comparator CMP2 to compare the output of the arithmetic unit f as the negative side input, and the output of the adder ADD23 as the positive side input, A comparator CMP3 that compares the output of the arithmetic unit f as a negative input is shown.

  This embodiment is an effective means for lighting a large number of discharge lamps having different lengths, and is characterized in that a correction signal that matches the characteristics of each discharge lamp is added to the output signal of a detector that detects the discharge lamp voltage. It is said. The discharge lamp voltage is roughly proportional to the length of the discharge lamp. For example, if the discharge lamp voltage of a fluorescent discharge lamp having a length of 2400 mm is 300 V, it is considered that there is a potential difference of about 12 V per 100 mm length of the discharge lamp. When a plurality of discharge lamps having a length of 2400 mm and 2000 mm are turned on simultaneously, a difference of about 50 V occurs in the discharge lamp voltage under the condition that the light flux amount per unit length is the same. This voltage difference is canceled out by the correction signal, so that it looks as if the same discharge lamp is lit.

  This embodiment is useful when lighting discharge lamps having different lengths in a discharge lamp having a high discharge lamp voltage. For example, when two discharge lamps of three types are lit, it is more long-term to calculate the reference voltage from the sampling values from all six types than to calculate the reference voltage from two types of each. This is because it is possible to reduce the influence of various characteristic fluctuations and ambient temperature.

  By using this embodiment, it is possible to provide a safe discharge lamp lighting device that reliably detects the discharge lamp life and controls lighting even when the number of discharge lamps is small.

(Embodiment 8)
FIG. 11 shows the configuration of the eighth embodiment of the present invention. In the present embodiment, the configuration for detecting the peak voltage is used as the detectors VS1 to VS3 for detecting the discharge lamp voltage in the first embodiment. At both ends of the high-frequency voltage source PS1, there are a series circuit of impedance Z11, discharge lamp La1 and impedance Z12, a series circuit of impedance Z21, discharge lamp La2 and impedance Z22, a series circuit of impedance Z31, discharge lamp La3 and impedance Z32, and a capacitor. A series circuit of CC1 and CC2 is connected in parallel. The connection point between the capacitors CC1 and CC2 is connected to the ground. Of the potential at the connection point between the impedance Z11 and the discharge lamp La1 and the potential at the connection point between the discharge lamp La1 and the impedance Z12, a signal proportional to the higher peak voltage as viewed from the ground level is output from the voltage detector VS1. . The configuration of the voltage detectors VS2 and VS3 is the same. The present invention can also be applied to the other embodiments 2 to 7.

(Embodiment 9)
FIG. 12 shows the configuration of the ninth embodiment of the present invention. In the present embodiment, the configuration for detecting the discharge lamp current is used as the detectors VS1 to VS3 in the first embodiment. Current detection resistors Rs1, Rs2, and Rs3 are connected in series to the series circuit of impedance Z1 and discharge lamp La1, the series circuit of impedance Z2 and discharge lamp La2, and the series circuit of impedance Z3 and discharge lamp La3, respectively. The discharge lamp current flowing through each of the discharge lamps La1, La2, and La3 is subjected to current-voltage conversion by the current detection resistors Rs1, Rs2, and Rs3, and outputs a signal that is full-wave rectified and smoothed by the voltage detectors VS1, VS2, and VS3. . The principle for calculating the reference voltage Vref is the same as in the first embodiment, except that the reference voltage Vref is applied to the + side inputs of the comparators CMP1, CMP2, and CMP3. Since the discharge lamp has negative resistance characteristics, it is detected that the average value of the discharge lamp voltage has increased above the reference voltage by detecting that the average value of the discharge lamp current has decreased below the reference voltage. be able to. The present invention can also be applied to the other embodiments 2 to 7.

(Embodiment 10)
FIG. 13 shows the configuration of the tenth embodiment of the present invention. This embodiment is an example of detecting a loose contact (contact failure) of a connector as an abnormality of a discharge lamp in a discharge lamp lighting device using a connector between a ballast and a discharge lamp.

  A series circuit of an impedance Z1, a connector CON1, and a discharge lamp La1, a series circuit of an impedance Z2, a connector CON2, and a discharge lamp La2, and a series circuit of an impedance Z3, a connector CON3, and a discharge lamp La3 are arranged in parallel at both ends of the high-frequency voltage source PS1. It is connected. When loose contact (contact failure) occurs in any of the connectors CON1, CON2, and CON3, the voltage rises due to arc discharge in the contact failure portion, and the voltage of the series circuit of the connector and the discharge lamp rises. Therefore, in this embodiment, it is possible to detect a loose contact (contact failure) by detecting the voltage across the series circuit of the connectors CON1, CON2, CON3 and the discharge lamps La1, La2, La3 by the detectors VS1, VS2, VS3. It is characterized by that. In addition, as the calculator f, any of the calculation methods of the first to fourth embodiments described above may be used. Further, the correction signals of the fifth to seventh embodiments may be added, or the detectors of the eighth and ninth embodiments may be used.

  By using this embodiment, it is possible to provide a safe discharge lamp lighting device that reliably detects abnormalities and lifetimes of discharge lamps and controls lighting.

(Embodiment 11)
FIG. 14 shows the configuration of the eleventh embodiment of the present invention. This embodiment includes the reference voltage Vref2 for comparing absolute values in addition to the reference voltage (output of the arithmetic unit f) for comparing relative values in the first to tenth embodiments, and An abnormality is detected by a logical sum of comparison results.

  In the present embodiment, there is a configuration in which three discharge lamp lighting circuits are connected in parallel to the output of one high-frequency voltage source PS1. The first discharge lamp lighting circuit is a series circuit of impedance Z1 and discharge lamp La1, the second discharge lamp lighting circuit is a series circuit of impedance Z2 and discharge lamp La2, and the third discharge lamp lighting circuit is impedance Z3. And a discharge lamp La3 in series. It is assumed that the three discharge lamps are the same type of discharge lamp and have the same ambient temperature and lighting period. One electrode end of each of the discharge lamps La1 to La3 is grounded. In addition, detectors VS1 to VS3 are provided which input high-frequency voltages at the electrode ends on the non-ground side of the discharge lamps La1 to La3 and output a signal subjected to full-wave rectification and smoothing.

  The outputs of the detectors VS1 to VS3 are input to the arithmetic unit f, a reference voltage for comparison of relative values is created, and applied to the negative side inputs of the comparators CMP1, CMP2, and CMP3. As the calculator f, any of the calculation methods of the first to fourth embodiments may be used. Moreover, you may add the correction signal of Embodiment 5-7.

  In the present embodiment, in addition to the three comparators CMP1 to CMP3 that compare the outputs of the detectors VS1 to VS3 and the output of the arithmetic unit f, the outputs of the detectors VS1 to VS3 and the reference signal Vref2 are compared. Three comparators CMP11, CMP21, and CMP31 are provided. Further, an OR circuit OR1 that logically sums the output of the comparator CMP1 and the output of the comparator CMP11, an OR circuit OR2 that logically sums the output of the comparator CMP2 and the output of the comparator CMP21, and the output of the comparator CMP3 and the comparator An OR circuit OR3 for logically summing the outputs of the CMP 31 is provided.

  The present embodiment is characterized in that lifetime detection is performed by comparison with a preset reference signal Vref2 at the same time as lifetime detection using the reference voltage created by the computing unit f. The reference voltage created by the arithmetic unit f is excellent in detecting a change in relative value, but cannot be detected when abnormality of the entire discharge lamp occurs simultaneously. For example, even if the normal discharge lamp voltage is 200 V and the three discharge lamps simultaneously have an abnormal discharge lamp voltage 400 V at the time of life, the life cannot be detected only by relative value detection. Therefore, by combining with a detecting means for comparing with an absolute value (fixed value), all discharge lamps can be detected even if they become abnormal at the same time.

  By using this embodiment, it is possible to provide a safe discharge lamp lighting device that reliably detects abnormalities and lifetimes of discharge lamps and controls lighting.

Embodiment 12
FIG. 15 shows the configuration of the twelfth embodiment of the present invention. The present embodiment is an example in which absolute value detection is used together as in the eleventh embodiment. The present embodiment is different from the eleventh embodiment in that the outputs of the detectors VS1 to VS3 and the three comparators CMP11 to CMP31 for comparing the reference signal Vref2 are omitted, and the output of the comparator CMP1 and the comparator CMP11 are omitted. An OR circuit OR1 that logically sums the outputs, an OR circuit OR2 that logically sums the output of the comparator CMP2 and the output of the CMP21, and an OR circuit OR3 that logically sums the output of the comparator CMP3 and the output of the comparator CMP31 are omitted. The comparator CMP10 for comparing the output of the comparator f with a predetermined reference voltage Vref2 is provided. If this embodiment is used, the same effect as that of Embodiment 11 can be realized with a small number of components.

  By using this embodiment, it is possible to provide a safe discharge lamp lighting device that reliably detects abnormalities and lifetimes of discharge lamps and controls lighting.

(Embodiment 13)
FIG. 16 shows the configuration of the thirteenth embodiment of the present invention. In the present embodiment, an adder ADD1 that sets a threshold value on the upper side by adding a predetermined detection margin ΔVs to the average value generated by the arithmetic unit f, and a predetermined detection from the average value generated by the arithmetic unit f. A subtractor SUB1 that subtracts the margin ΔVs to set a lower threshold value, and when the outputs of the detectors VS1 to VS3 are higher than the upper threshold value or lower than the lower threshold value In addition, an abnormality is detected.

  The present embodiment is characterized in that the life detection on the upper side of the average value calculated by the computing unit f and the abnormality detection on the lower side are simultaneously performed. As the abnormality detection on the lower side, for example, when the discharge lamp is short-circuited or grounded, the output signal levels of the detectors VS1 to VS3 are lowered. If the output signal level is lower than the lower threshold, it can be detected as a discharge lamp abnormality.

  In the present embodiment, there is a configuration in which three discharge lamp lighting circuits are connected in parallel to the output of one high-frequency voltage source PS1. The first discharge lamp lighting circuit is a series circuit of impedance Z1 and discharge lamp La1, the second discharge lamp lighting circuit is a series circuit of impedance Z2 and discharge lamp La2, and the third discharge lamp lighting circuit is impedance Z3. And a discharge lamp La3 in series. One electrode end of each of the discharge lamps La1 to La3 is grounded. In addition, detectors VS1 to VS3 are provided which input high-frequency voltages at the electrode ends on the non-ground side of the discharge lamps La1 to La3 and output a signal subjected to full-wave rectification and smoothing.

  In this embodiment, in addition to the three comparators CMP1 to CMP3 for comparing the outputs of the detectors VS1 to VS3 and the output of the adder ADD1, the outputs of the detectors VS1 to VS3 and the output of the subtractor SUB1 are used. Three comparators CMP11, CMP21, and CMP31 for comparison are provided. Further, an OR circuit OR1 that logically sums the output of the comparator CMP1 and the output of the comparator CMP11, an OR circuit OR2 that logically sums the output of the comparator CMP2 and the output of the comparator CMP21, and the output of the comparator CMP3 and the comparator An OR circuit OR3 for logically summing the outputs of the CMP 31 is provided.

  The outputs of the detectors VS1 to VS3 are input to the arithmetic unit f, the average value is calculated, the detection margin ΔVs is added by the adder ADD1, and applied to the negative side inputs of the comparators CMP1, CMP2, and CMP3. Further, the detection margin ΔVs is subtracted by the subtracter SUB1 and applied to the + side inputs of the comparators CMP11, CMP21, and CMP31.

  Thereby, the comparators CMP1, CMP11 and the OR circuit OR1 constitute a window comparator for determining whether or not the detection signal of the detector VS1 is within ± ΔVs with respect to the average value output from the arithmetic unit f. . Similarly, it is determined whether or not the detection signals of the detectors VS2 and VS3 are within ± ΔVs with respect to the average value output from the calculator f.

  By using this embodiment, it is possible to provide a safe discharge lamp lighting device that reliably detects abnormalities and lifetimes of discharge lamps and controls lighting.

(Embodiment 14)
FIG. 17 shows a configuration diagram of the fourteenth embodiment. In the present embodiment, as in the basic configuration of FIG. 1, the high-frequency voltage sources PS1, PS2, and PS3 for the discharge lamps La1, La2, and La3 are independent. When the discharge lamp La1 is abnormal, the high-frequency voltage sources PS1, PS2, and PS3 receive the detection output EN1. The oscillation of the voltage source PS1 is stopped. When the discharge lamp La2 is abnormal, the detection output EN2 is received and the high-frequency voltage source PS2 is stopped. When the discharge lamp La3 is abnormal, the detection output EN3 is received and the high-frequency voltage source PS3 is oscillated. Stop. As a result, the output of the detector corresponding to the discharge lamp in which abnormality is detected becomes zero. Then, since the reference voltage calculated by the calculator f decreases, other normal discharge lamps are also determined to be abnormal. In the basic configuration of FIG. 1, if any one of the discharge lamps is abnormal using this principle, the other discharge lamps can also be stopped in a chained manner. In this embodiment, it is determined that there is an abnormality. In order to stop only the discharge lamp, the controller FC1 receives the outputs from the comparators CMP1, CMP2, and CMP3 and performs control to change the arithmetic expression of the arithmetic unit f by the controller FC1.

  For example, when the discharge lamp La1 reaches the end of life and the comparator CMP1 outputs the life determination signal EN1, the controller FC1 sends a signal for changing the arithmetic expression of the arithmetic unit f accordingly. Here, the change of the arithmetic expression is an operation of excluding the detector signal of the life discharge lamp La1 from the calculation. As a result, the lighting state of the discharge lamps other than the life discharge lamp can be continuously detected. In this way, in a discharge lamp lighting device in which a plurality of lamps are lit, when only one lamp has reached the end of life, only the discharge lamp power supply that has reached the end of life is stopped, and the remaining discharge lamps continue to be lit. By changing the equation, the accuracy of life detection can be maintained.

  By using this embodiment, it is possible to provide a highly convenient discharge lamp lighting device by turning off the life discharge lamp and lighting the remaining discharge lamps while maintaining the detection accuracy.

  Note that this embodiment can also be applied to a case where the output is controlled so as to suppress the output instead of turning off the life discharge lamp, and even in this case, the detector signal of the life discharge lamp is excluded from the calculation. Thus, the remaining discharge lamps can be lit while maintaining the detection accuracy.

(Embodiment 15)
FIG. 18 shows a configuration diagram of the fifteenth embodiment. Also in the present embodiment, the high-frequency voltage sources PS1, PS2, and PS3 for the discharge lamps La1, La2, and La3 are independent as in the basic configuration of FIG. 1, and the high-frequency voltage sources PS1, PS2, and PS3 are respectively constant. Oscillation and stop are repeated in a cycle.

  As will be described later, in a discharge lamp lighting device used in a backlight unit of a liquid crystal display device, a plurality of discharge lamps are sequentially turned on in synchronization with a video signal to improve video display quality or screen brightness. Is adjusted (burst dimming). In such a case, the detection signals of the detectors VS1 to VS3 that detect the discharge lamp voltages of the discharge lamps La1 to La3 are output in a jumping manner as shown in FIG.

  The present embodiment is an example of life detection when a plurality of discharge lamps are not lit at the same time and are blinking. The outputs of the detectors VS1 to Vs3 are input to sample and hold circuits SH1 to SH3, respectively. All outputs x, y, z of the sample and hold circuits SH1 to SH3 are input to the calculator f, and the reference voltage r is calculated. Further, three comparators CMP1 to CMP3 for comparing the outputs of the detectors VS1 to VS3 and the output r of the arithmetic unit f are provided. As the calculator f, any of the calculation methods of the above-described first to fourth embodiments may be used, but here, a case where an average value is calculated will be described.

  The operation of this embodiment will be described below with reference to FIG. In the figure, the output signals of the detectors VS1 to VS3, the output signals of the sample and hold circuits SH1 to SH3, and the output signal r of the arithmetic unit f are shown. As for the detection voltages VS1 to VS3, detection signals are generated in a time-sharing manner according to the discharge lamp blinking by the high-frequency voltage sources PS1 to PS3. The sample and hold circuits SH1 to SH3 sample the detection voltage in synchronization with the discharge lamp lighting timing and hold it until the next detection timing. The arithmetic unit f inputs the detection signal output from the sample and hold circuit as needed and performs an average value calculation. As described above, the present embodiment is characterized in that the average value is calculated after the detector signal is once held in the sample and hold circuit.

  If this embodiment is used, the discharge lamp lighting device which can detect the lifetime of a discharge lamp reliably also in various blinking lighting states can be provided.

(Embodiment 16)
FIG. 20 shows a configuration diagram of the sixteenth embodiment. The figure shows a discharge lamp La1 and a fixture LE1 comprising a lighting device INV1 for lighting the discharge lamp, a discharge lamp La2 and a fixture LE2 comprising a lighting device INV2 for lighting the discharge lamp, and a discharge lamp La3. An appliance LE3 including a lighting device INV3 for lighting the discharge lamp is provided. Each of the appliances LE1 to LE3 has a communication function, transmits the respective discharge lamp voltage detection signals VS1 to VS3 to the detection controller DET, and outputs the abnormality determination outputs EN1 to EN3 of the detection controller DET to the appliances LE1 to LE3, respectively. It is comprised so that it may receive. The detection controller DET compares the average value calculator f that performs the average value calculation with the detection signals VS1 to VS3 as inputs, and compares the average value calculation output Vref as a negative input and the detection signals VS1 to VS3 as a positive input. It consists of containers CMP1 to CMP3. In this case, the detection signals VS1 to VS3 may not be voltage values but may be digital signals. The calculator f is not limited to the average value calculation, and any of the calculation methods of the first to fourth embodiments described above may be used.

  The present embodiment is characterized in that the arithmetic unit f and the comparators CMP1 to CMP3 are arranged away from the discharge lamp lighting circuit for lighting the discharge lamp. By using this embodiment, it is possible to accurately detect the life of the discharge lamp in a lighting fixture in a space where the lighting conditions and temperature conditions of the discharge lamp are constant.

  By using this embodiment, it is possible to provide a safe discharge lamp lighting device that reliably detects abnormalities and lifetimes of discharge lamps and controls lighting.

(Embodiment 17)
The configuration of the backlight device according to the present invention will be briefly described with reference to FIG. 21. The backlight unit BL includes a plurality of hot cathode lamps La and a housing 20 that stores these hot cathode lamps La. . Here, the hot cathode lamp La is provided with a filament at both ends of a glass tube. The backlight unit BL is used by being arranged on the back side of a liquid crystal panel (not shown), and the housing 20 has a reflecting plate 21, a side plate 22, a mounting frame 23, a translucent plate 24, a lighting device (not shown: Generally disposed on the back side of the backlight unit BL). In general, the translucent plate 24 is formed by laminating a diffusion plate 25, a diffusion sheet 26, and a lens sheet 27 in order from the back side. With the above configuration, light from the plurality of hot cathode lamps La lit by the lighting device is diffused when passing through the diffusion plate 25 and is emitted from the entire surface of the diffusion sheet 26 as parallel light that is averaged.

  In recent years, hot cathode lamps have attracted attention as backlight devices for large liquid crystal display devices. A hot cathode lamp has a merit that the number of lamps can be reduced because a large amount of electric power can be supplied per lamp, and that the lamp voltage is 1/10 or less that of a cold cathode lamp because of arc discharge. However, since the hot cathode lamp has a filament, the lifetime is shorter than that of the cold cathode lamp, and the discharge lamp voltage becomes higher at the end of the lifetime. Therefore, when the configuration of each of the above-described embodiments is used to detect a discharge lamp with a high discharge lamp voltage among a plurality of discharge lamps, control may be performed to stop or suppress output.

  It goes without saying that the configuration of the present invention can also be applied to a general lighting device having a plurality of discharge lamps.

It is a circuit diagram which shows the basic composition of this invention. It is a circuit diagram which shows the structure of Embodiment 1 of this invention. It is a principal part circuit diagram for operation | movement description of Embodiment 1 of this invention. It is a principal part circuit diagram for operation | movement description of Embodiment 1 of this invention. It is a circuit diagram which shows the principal part structure of Embodiment 2 of this invention. It is a circuit diagram which shows the principal part structure of Embodiment 3 of this invention. It is a circuit diagram which shows the principal part structure of Embodiment 4 of this invention. It is a circuit diagram which shows the principal part structure of Embodiment 5 of this invention. It is a circuit diagram which shows the principal part structure of Embodiment 6 of this invention. It is a circuit diagram which shows the principal part structure of Embodiment 7 of this invention. It is a circuit diagram which shows the structure of Embodiment 8 of this invention. It is a circuit diagram which shows the structure of Embodiment 9 of this invention. It is a circuit diagram which shows the structure of Embodiment 10 of this invention. It is a circuit diagram which shows the structure of Embodiment 11 of this invention. It is a circuit diagram which shows the structure of Embodiment 12 of this invention. It is a circuit diagram which shows the structure of Embodiment 13 of this invention. It is a circuit diagram which shows the structure of Embodiment 14 of this invention. It is a circuit diagram which shows the structure of Embodiment 15 of this invention. It is a wave form diagram for operation | movement description of Embodiment 15 of this invention. It is a circuit diagram which shows the structure of Embodiment 16 of this invention. It is a disassembled perspective view which shows schematic structure of the backlight apparatus of this invention.

Explanation of symbols

La1, La2, La3 discharge lamp VS1, VS2, VS3 detector ADD1 adder AMP1 amplifier Vref reference voltage CMP1, CMP2, CMP3 comparator

Claims (13)

In a discharge lamp lighting device having an impedance for connecting a discharge lamp to a power source and a detector for detecting a physical quantity of the discharge lamp, the discharge lamp includes a plurality of discharge lamps and the detector, and the output signals of all the detectors are input. A comparator that outputs a reference signal based on a predetermined calculation method; a reference signal that is output from the calculator; and a comparator that compares the output signal of the detector. A discharge lamp lighting device characterized by controlling the lighting of a discharge lamp by means of the above. The discharge lamp lighting device according to claim 1, wherein the calculation method of the calculator uses an arithmetic average value of input values as a calculation result. The discharge lamp lighting device according to claim 1, wherein the calculation method of the calculator uses a minimum value of input values as a calculation result. The discharge lamp lighting device according to claim 1, wherein the number of discharge lamps and detectors is three or more, and the calculation method of the calculator uses a median value of input values as a calculation result. The discharge lamp according to claim 1, wherein the number of discharge lamps and detectors is three or more, and the calculation method of the calculator is an arithmetic average of values other than the maximum value of the input values. Electric light lighting device. In accordance with a signal obtained by logically summing the output signal of the comparator and the output signal of the second comparator, comprising at least one second comparator for comparing the output signal of the detector with a second reference signal. The discharge lamp lighting device according to claim 1, wherein lighting control of the discharge lamp is performed. The discharge lamp lighting device according to any one of claims 1 to 6, further comprising means for adding a predetermined correction value to a reference signal of the arithmetic unit. The discharge lamp lighting device according to any one of claims 1 to 6, further comprising means for subtracting a predetermined correction value from a reference signal of the arithmetic unit. The discharge lamp lighting device according to any one of claims 1 to 8, wherein the lighting control of the discharge lamp is to suppress or turn off the output of at least one lamp. The discharge lamp lighting device according to claim 1, wherein the calculator changes a calculation method according to at least one output of the comparator. The discharge lamp lighting device according to any one of claims 1 to 10, wherein the discharge lamp is connected via at least one connector. The illuminating device provided with the discharge lamp lighting device in any one of Claims 1-11. The backlight apparatus provided with the discharge lamp lighting device in any one of Claims 1-11.

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