JP4479406B2 - Discharge lamp lighting device and lighting device - Google Patents

Description

  The present invention relates to a discharge lamp lighting device that emits light from a discharge lamp. And it is related with the illuminating device provided with such a discharge lamp lighting device.

  For example, as a discharge lamp lighting device for lighting a discharge lamp typified by a fluorescent lamp, the discharge lamp is turned on at a high frequency using an inverter circuit that converts a low-frequency commercial power source into a high frequency, for example, to a dimming signal input from the outside Accordingly, there is known a discharge lamp lighting device that controls the amount of light emitted from the discharge lamp by controlling the power supplied to the discharge lamp (see, for example, Patent Document 1). In such a discharge lamp lighting device, it is required to obtain stable dimming performance that does not cause instability such as variation in light output and flickering even to a lower luminous flux.

  In order to meet this demand, a discharge lamp lighting device that detects a lighting state of a discharge lamp (for example, a fluorescent lamp) and performs feedback control so that the discharge lamp has a predetermined output in accordance with an input dimming signal. It has been known. As a device using such feedback control, a lamp current flowing through the discharge lamp or a voltage applied to the discharge lamp is detected, and the current or voltage is a predetermined current value or voltage value corresponding to the dimming signal. In general, a feedback control is performed so that the following is satisfied, or a lamp power that is output to the discharge lamp is detected and the feedback control is performed.

  FIG. 8 is a circuit diagram showing a configuration of a discharge lamp lighting device according to the background art. In the discharge lamp lighting device shown in FIG. 8, the input AC voltage AC is full-wave rectified by the diode bridge DB, and is applied to both ends of the capacitor C1 by the chopper circuit 101 including the inductor L1, the switching element Q1, the diode D1, and the capacitor C1. A predetermined DC voltage Vdc is generated. The inverter circuit 102 including the series circuit of the switching elements Q2 and Q3 and the resistor R1 and the capacitor C3 converts the DC voltage Vdc into a high frequency voltage by switching the DC voltage Vdc at the high frequency with the switching elements Q2 and Q3. . Here, the resistor R1 is for detecting the current flowing through the switching element Q3 and equivalently detecting the power output from the inverter circuit based on the average value of the detected current.

  In addition, the load circuit 103 including the inductor L2, the capacitor C2, and the discharge lamp FL converts the high-frequency voltage generated by the inverter circuit 102 into a substantially sine wave shape by resonance of the inductor L2 and the capacitor C2, and is applied to the discharge lamp FL. It supplies the electric power. The inverter output power detected by the resistor R1 is input to the inverting input terminal of the operational amplifier OP1 via the resistor R2, and the command value voltage Vref1 is input to the non-inverting input terminal of the operational amplifier. The operational amplifier OP1 compares the two input signals, and changes the output voltage of the operational amplifier OP1 so that the difference between them becomes small. The command value voltage Vref1 is changed according to the input dimming signal.

The output terminal of the operational amplifier OP1 is connected to a VCO (voltage controlled oscillator) 104, and the output power of the inverter circuit 102 is controlled by changing the drive frequency of the inverter circuit 102 in accordance with the output voltage of the operational amplifier OP1. The feedback operation is performed so that the detected voltage, that is, the voltage representing the output power of the inverter is substantially the same as the command value voltage Vref1. Thereby, the output voltage of the inverter is adjusted according to the dimming signal. Thus, in a discharge lamp lighting device equipped with feedback control, for example, even when the characteristics of the discharge lamp change due to variations in the characteristics of the discharge lamp or changes in ambient temperature, a substantially constant power is supplied to the discharge lamp. By supplying, there is an advantage that the brightness of the discharge lamp can be made substantially constant.
JP 2002-75681 A

  Incidentally, as described above, in the case of detecting the lamp current flowing through the discharge lamp, the lamp power supplied to the discharge lamp, etc., and performing feedback control of the power output to the discharge lamp, FIGS. ), The lamp current and the lamp power decrease as the dimming ratio decreases (the light emission amount decreases). For example, in the region where the dimming ratio is several percent or less, the detected values of the lamp current and the lamp power As a result, the power supply to the discharge lamp FL is likely to be affected by noise superimposed on the feedback circuit such as the resistor R1, the operational amplifier OP1, and the VCO 104, and the instability of these feedback circuits. There is a problem that the accuracy is lowered, the emission of the discharge lamp FL becomes unstable, and the discharge lamp FL flickers or disappears.

  The present invention has been made in view of such problems, and provides a discharge lamp lighting device capable of improving the stability of the light emission operation of the discharge lamp when the dimming ratio is lowered. Objective. And it aims at providing the illuminating device using such a discharge lamp lighting device.

  In order to achieve the above-described object, a discharge lamp lighting device according to the first means of the present invention supplies a high-frequency power to a discharge lamp to emit light, and indicates a light emission amount of the discharge lamp. A discharge lamp lighting device comprising: a dimming instruction receiving unit that receives a dimming instruction; and a control unit that controls the amount of power supplied by the power supply unit according to the dimming instruction received by the dimming instruction receiving unit. The control unit is received by the power detection unit that detects the amount of power supplied from the power supply unit to the discharge lamp, and the power amount detected by the power detection unit and the dimming instruction reception unit. A first feedback control unit for controlling the amount of power supplied by the power supply unit based on the dimming instruction, an impedance detection unit for detecting the impedance of the discharge lamp, and a detection by the impedance detection unit. A second feedback control unit that controls the amount of power supplied by the power supply unit based on the impedance that has been adjusted and the dimming instruction received by the dimming instruction receiving unit, and the first feedback control unit Controls the power supply amount when the power supply amount is equal to or higher than a predetermined power supply amount set in advance, while the second feedback control unit sets the power supply amount in advance. When the predetermined power supply amount is not satisfied, the power supply amount is mainly controlled.

  Further, in the above-described discharge lamp lighting device, the impedance detection unit includes a DC voltage superimposing unit that superimposes a DC voltage corresponding to the impedance of the discharge lamp on the discharge lamp, and a direct current superimposed on the discharge lamp. The impedance of the discharge lamp is detected based on the voltage.

  In the above-described discharge lamp lighting device, the first feedback control unit includes a signal value of an electric energy signal indicating the electric energy detected by the electric power detection unit and the adjustment received by the dimming instruction reception unit. The second feedback control unit controls the amount of power supplied by the power supply unit so as to reduce the difference from the first instruction signal value representing the light instruction, and the second feedback control unit detects the impedance detected by the impedance detection unit. And the second instruction signal value representing the dimming instruction accepted by the dimming instruction accepting unit are amplified and added to the first instruction signal value to obtain the impedance. The power supply amount by the power supply unit is controlled to reduce the difference between the signal value to be expressed and the second instruction signal value.

  Furthermore, in the above-described discharge lamp lighting device, the second feedback control unit is characterized in that the difference gain is increased or decreased according to the amount of light emission in the discharge lamp.

  Further, in the above-described discharge lamp lighting device, the second feedback control unit increases or decreases the difference amplification factor according to increase or decrease of the light emission amount in the discharge lamp represented by the second instruction signal value. It is characterized by being.

  In the above-described discharge lamp lighting device, the second feedback control unit decreases the amplification factor of the difference in accordance with the increase or decrease of the impedance detected by the impedance detection unit. .

  Furthermore, the illumination device according to the second means of the present invention includes a discharge lamp lighting device for lighting a discharge lamp, a housing that houses the discharge lamp lighting device, and the discharge lamp in the discharge lamp lighting device. A socket for connection, wherein the discharge lamp lighting device is the discharge lamp lighting device described above.

  In the discharge lamp lighting device and the lighting device having such a configuration, when the power supply amount is equal to or higher than a predetermined power supply amount set in advance, the power supply amount is mainly controlled by the first feedback control unit. On the other hand, when the power supply amount is less than the predetermined power supply amount set in advance, the power supply amount is mainly controlled by the second feedback control unit. The power supply amount is controlled based on the change in the impedance of the lamp, and the stability of the light emission operation of the discharge lamp can be improved when the dimming ratio is lowered.

  Embodiments according to the present invention will be described below with reference to the drawings. In addition, the structure which attached | subjected the same code | symbol in each figure shows that it is the same structure, The description is abbreviate | omitted.

(First embodiment)
FIG. 1 is a perspective view illustrating an example of an appearance of a lighting device 1 according to an embodiment of the present invention. FIG. 2 is a circuit diagram showing an example of the configuration of the discharge lamp lighting device 2 according to the first embodiment of the present invention. A lighting device 1 shown in FIG. 1 includes a discharge lamp lighting device 2 (not shown), a housing 3 that houses the discharge lamp lighting device 2, and a socket 4 for connecting the discharge lamp FL to the discharge lamp lighting device 2. I have.

  The discharge lamp lighting device 2 shown in FIG. 2 includes a chopper circuit 5, an inverter circuit 6, which corresponds to an example of a power supply unit, a load circuit 7, a control unit 8, and a dimming instruction receiving unit 9. The chopper circuit 5 is a circuit that generates, for example, a DC voltage Vdc from a commercial AC power supply voltage AC and outputs the DC voltage Vdc to the inverter circuit 6. The chopper circuit 5 includes a diode bridge DB that rectifies the AC power supply voltage AC in full wave, and an output terminal of the diode bridge DB. A series circuit of an inductor L1 and a switching element Q1 is connected between them, and a series circuit of a diode D1 and a smoothing capacitor C1 is connected in parallel with the switching element Q1. The connection point between the smoothing capacitor C1 and the switching element Q1 is connected to the ground, and the voltage across the smoothing capacitor C1 is output to the inverter circuit 6 as the DC voltage Vdc.

  The inverter circuit 6 is interposed between a series circuit of switching elements Q2 and Q3 and a resistor R1 connected in parallel with the smoothing capacitor C1, and a connection point between the resistor R1 and the ground and one filament f1 of the discharge lamp FL. And a capacitor C3, which converts the DC voltage Vdc into a high-frequency voltage for causing the discharge lamp FL to emit light by switching the DC voltage Vdc at a high frequency by the switching elements Q2 and Q3. The load circuit 7 is configured to be connectable to the discharge lamp FL via the socket 4, and includes an inductor L2 that connects a connection point between the switching elements Q2 and Q3 and the other filament f2 of the discharge lamp FL, and a discharge lamp. And a capacitor C2 connected in parallel with the FL. The high-frequency voltage supplied from the inverter circuit 6 is converted into a substantially sinusoidal shape by resonance of the inductor L2 and the capacitor C2, and predetermined power is supplied to the discharge lamp FL.

  The control unit 8 includes a resistor R2, R6, a capacitor C4, an operational amplifier OP1, a VCO 10, an inverter drive circuit 11, and a command value voltage generation circuit 12 that generates a command value voltage Vref1 corresponding to the first instruction signal value. A second feedback circuit 82 comprising a feedback circuit 81, resistors R3, R4, R5, R7, a capacitor C5, an operational amplifier OP2, and a command value voltage generation circuit 13 that generates a command value voltage Vref2 corresponding to the second instruction signal value. With. In this case, the first feedback circuit 81 corresponds to an example of a first feedback control unit, the second feedback circuit 82 corresponds to an example of a second feedback control unit, and the resistor R5 corresponds to an example of an impedance detection unit. ing.

  The dimming instruction receiving unit 9 receives a dimming instruction for instructing the light emission amount of the discharge lamp FL, and outputs a dimming signal SC representing the dimming instruction to the command value voltage generation circuits 12 and 13. A dimming switch that accepts an operation input instructing dimming from a user, or a connector that connects wiring for transmitting a dimming signal SC from a dimming switch provided outside the lighting device 1; Or a wiring for transmitting a dimming signal SC from a dimming circuit for automatically dimming the brightness of the discharge lamp. The command value voltage generation circuits 12 and 13 output command value voltages Vref1 and Vref2 in response to the dimming signal SC from the dimming instruction receiving unit 9, respectively.

  A resistor R3 is connected between the connection point between the inductor L2 and the filament f2 and the connection point between the capacitor C3 and the filament f1, and the connection point between the capacitor C3 and the filament f1 is a series circuit of resistors R4 and R5. Is connected to ground through In this case, the resistors R3, R4, and R5 correspond to an example of DC voltage superimposing means. Further, the connection point of the resistors R4 and R5 is connected to the inverting input terminal of the operational amplifier OP2, the capacitor C5 is connected between the inverting input terminal and the output terminal of the operational amplifier OP2, and the command value is applied to the non-inverting input terminal of the operational amplifier OP2. A voltage generation circuit 13 is connected.

  Further, one end of the resistor R2 is connected to the connection point between the switching element Q3 and the resistor R1 in the inverter circuit 6, the other end is connected to the inverting input terminal of the operational amplifier OP1, and the inverting input terminal and the output terminal of the operational amplifier OP1 are connected. A capacitor C4 is connected between them. In this case, the resistor R1 corresponds to an example of a power detection unit. Then, the command value voltage Vref1 output from the command value voltage generation circuit 12 via the resistor R6 and the output voltage of the operational amplifier OP2 are added via the resistor R7 and input to the non-inverting input terminal of the operational amplifier OP1. By outputting the output signal from OP2 to the VCO 10, a frequency signal that is the operating frequency of the inverter circuit 6 is output from the VCO 10 to the inverter drive circuit 11, and the control signal is sent from the inverter drive circuit 11 to the gates of the switching elements Q2 and Q3. Is output, the switching elements Q2 and Q3 are alternately turned on and off at a frequency corresponding to the frequency signal from the VCO 10, and the power supplied from the inverter circuit 6 to the discharge lamp FL is feedback-controlled. ing.

  Next, the operation of the discharge lamp lighting device 2 configured as described above will be described. First, a DC voltage Vdc is generated from the AC voltage AC by the chopper circuit 5, and a high frequency voltage generated from the DC voltage Vdc by the inverter circuit 6 is supplied to the load circuit 7, which is caused by resonance between the inductor L2 and the capacitor C2. When the resonance voltage is applied to the discharge lamp FL, the discharge lamp FL is lit.

  Then, since the DC voltage Vdc is constant in the inverter circuit 6, the current flowing through the resistor R1 is proportional to the amount of power supplied from the inverter circuit 6 to the load circuit 7. Therefore, in the first feedback circuit 81, the voltage input from the resistor R1 to the non-inverting input terminal of the operational amplifier OP1 via the resistor R2 is proportional to the amount of power supplied from the inverter circuit 6 to the load circuit 7. The amount of power detected by R1 is acquired by the operational amplifier OP1.

  Further, a high frequency rectangular wave voltage generated at the connection point between the switching element Q2 and the switching element Q3 is applied to the discharge lamp FL, and a DC voltage corresponding to the impedance of the discharge lamp FL is applied by the resistors R3, R4, and R5. Superposed on the high frequency voltage. The DC voltage component superimposed on the high frequency voltage is divided by a parallel circuit of the resistor R3 and the discharge lamp FL and a series circuit of the resistor R4 and the resistor R5, and the DC voltage generated at both ends of the resistor R5 is released. The detection voltage Vk indicating the equivalent impedance of the electric lamp FL is detected by the second feedback circuit 82. In this case, if the switching duty of switching elements Q2 and Q3 is 50%, the DC component of the high-frequency rectangular wave voltage is ½ of DC voltage Vdc.

  Then, the dimming instruction receiving unit 9 receives a dimming instruction for reducing the light emission amount of the discharge lamp FL (decreasing the dimming ratio), and generates a command value voltage by the dimming signal SC from the dimming instruction receiving unit 9. When the command value voltage Vref1 of the circuit 12 is decreased, a control signal is output to the VCO 10 by the operational amplifier OP1 to decrease the power supply from the inverter circuit 6 to the discharge lamp FL, and the switching element Q2 is switched by the VCO 10 and the inverter drive circuit 11. , Q3 on / off frequency is controlled to dim the discharge lamp FL, and the dimming ratio decreases.

  FIG. 3 is a graph showing the relationship between the dimming ratio of the discharge lamp FL and the lamp equivalent resistance value which is the impedance of the discharge lamp FL. The lamp equivalent resistance value of the discharge lamp FL increases as the dimming ratio decreases. At this time, since the combined resistance value of the parallel circuit of the resistor R3 and the discharge lamp FL increases, the DC component of the voltage generated at both ends of the discharge lamp FL increases and the DC voltage generated at both ends of the resistor R5 decreases. Therefore, the second feedback circuit 82 can detect the equivalent impedance of the discharge lamp FL by detecting the DC voltage generated across the resistor R5 as the detection voltage Vk. In this case, when the equivalent impedance of the discharge lamp FL increases, the detection voltage Vk decreases, and when the equivalent impedance of the discharge lamp FL decreases, the detection voltage Vk increases.

  As shown in FIG. 3, since the lamp equivalent resistance value of the discharge lamp FL increases exponentially as the dimming ratio decreases, a slight fluctuation of the dimming ratio is greatly changed at the time of low beam dimming. Therefore, a low luminous flux with a dimming ratio lower than that in the case of detecting the lamp current flowing through the discharge lamp FL, the lamp power supplied to the discharge lamp FL, etc. as in the discharge lamp lighting device according to the background art. The effects of noise superimposed on the feedback circuit during dimming and the effects of instability of these feedback circuits are reduced, and slight characteristic fluctuations related to the amount of light emitted from the discharge lamp FL can be accurately detected. The stability of the light emission operation of the electric lamp can be improved.

  FIG. 4 is a waveform diagram showing voltage waveforms at the time of low luminous flux dimming generated at both ends of the discharge lamp FL in the discharge lamp lighting device 2 shown in FIG. FIG. 4A shows a voltage waveform during dimming in a normal temperature environment, and FIG. 4B shows a voltage waveform during dimming at a low temperature. First, as shown in FIG. 4 (a), the voltage across the discharge lamp at the time of low beam dimming in a normal temperature environment is equal to the high-frequency voltage component Vla # ac supplied from the inverter circuit. It has a waveform in which a DC voltage component Vla # dc corresponding to is superimposed. However, when the ambient temperature of the discharge lamp FL decreases in this state, the equivalent impedance increases due to the characteristic change of the discharge lamp FL, and the DC voltage component Vla # dc increases as shown in FIG. At the same time, the illuminance of the discharge lamp FL decreases, it becomes difficult to maintain a stable discharge, and flickering or extinction occurs.

  Therefore, in the second feedback circuit 82, when the detected voltage Vk is lower than the command value voltage Vref2, it is considered that the illuminance of the discharge lamp FL is lowered, and the detected voltage Vk detected by the resistor R5 by the operational amplifier OP2 and the command value. The difference between the voltage Vref2 is amplified and output to the operational amplifier OP1, and the output voltage of the operational amplifier OP2 added to the command value voltage Vref1 of the operational amplifier OP1 is increased, whereby the voltage applied to the non-inverting input terminal of the operational amplifier OP1 is increased. Increase the power supply from the inverter circuit 6 to the discharge lamp FL. Then, the detection voltage Vk increases, and the difference between the detection voltage Vk and the command value voltage Vref2 is reduced.

  On the other hand, when the detection voltage Vk rises above the command value voltage Vref2, it is considered that the illuminance of the discharge lamp FL has risen, and the operational amplifier OP2 amplifies the difference between the detection voltage Vk and the command value voltage Vref2 and outputs it to the operational amplifier OP1. Then, by reducing the output voltage of the operational amplifier OP2 added to the command value voltage Vref1 of the operational amplifier OP1, the voltage applied to the non-inverting input terminal of the operational amplifier OP1 is lowered, and the power from the inverter circuit 6 to the discharge lamp FL is reduced. Feedback control is performed to reduce the supply. As a result, the detection voltage Vk decreases, and the difference between the detection voltage Vk and the command value voltage Vref2 decreases.

  As a result, flickering and extinction associated with a decrease in discharge lamp illuminance when the ambient temperature decreases can be prevented.

  Further, as shown in FIG. 5A, the command value voltage Vref2 output from the command value voltage generation circuit 13 rises according to the increase of the dimming ratio indicated by the dimming signal SC, and is set in advance. The command value voltage Vref2 is set to be higher than the detection voltage Vk at a predetermined dimming ratio, for example, 40% or more. As shown in FIG. 5B, the operational amplifier OP2 is at a predetermined dimming ratio or higher. Output voltage is saturated with a power supply voltage (not shown) supplied to the operational amplifier OP2, for example, and is clamped.

  Then, when the power supply amount from the inverter circuit 6 to the discharge lamp FL is equal to or higher than a predetermined power supply amount set in advance, the command of the operational amplifier OP1 is issued by the operational amplifier OP2. Since the voltage value added to the value voltage Vref1 is a constant value regardless of the dimming ratio, feedback control according to the amount of power supplied from the inverter circuit 6 to the discharge lamp FL by the operational amplifier OP1 becomes dominant.

  Thereby, at the time of high luminous flux dimming exceeding a predetermined dimming ratio, that is, when the power supply amount from the inverter circuit 6 to the discharge lamp FL is equal to or greater than a predetermined power supply amount set in advance, the first feedback circuit While the feedback control according to the power supply amount from the inverter circuit 6 to the discharge lamp FL by 81 is dominant, the dimming ratio is lowered and the power supply amount from the inverter circuit 6 to the discharge lamp FL is preset. In a low luminous flux region where the predetermined power supply amount is not satisfied, and therefore the detected value of the lamp power detected by the resistor R1 is so small that the feedback control by the first feedback circuit 81 becomes unstable, the second feedback circuit Since the feedback control according to the equivalent impedance of the discharge lamp FL by 82 is dominant, the amount of power supply for causing the discharge lamp FL to emit light is determined. To improve the accuracy of Dobakku control, it is possible to suppress variations in light output by the light output variations and ambient temperature during Teihikaritabacho light, it is possible to improve the stability of the light-emitting operation of the discharge lamp. Further, the control by the first feedback circuit 81 and the control by the second feedback circuit 82 are provided without providing a switching circuit between the first feedback circuit 81 and the second feedback circuit 82 at the time of high beam dimming and low beam dimming. Therefore, the circuit configuration can be simplified.

  Note that the first feedback circuit 81 is not limited to the example in which the power supply amount from the inverter circuit 6 to the discharge lamp FL is feedback-controlled based on the power supply amount detected by the resistor R1, for example, the current flowing through the discharge lamp FL, The power supply amount from the inverter circuit 6 to the discharge lamp FL may be feedback-controlled by detecting the power consumed by the discharge lamp FL.

  The means for superimposing the DC voltage corresponding to the impedance of the discharge lamp FL on the discharge lamp FL is not limited to the resistors R3, R4, R5. For example, a method of superimposing the DC voltage Vdc from the chopper circuit 5 via the resistor, Other configurations such as a method of superimposing via a resistor from another DC power source may be used.

(Second Embodiment)
Next, a discharge lamp lighting device according to a second embodiment of the present invention will be described. FIG. 6 is a circuit diagram showing an example of the configuration of a discharge lamp lighting device 2a according to the second embodiment of the present invention. The configuration of the second feedback circuit 82a is different between the discharge lamp lighting device 2a shown in FIG. 6 and the discharge lamp lighting device 2 shown in FIG. That is, the second feedback circuit 82a shown in FIG. 6 amplifies the difference K between the detection voltage Vk and the dimming command value Vla # DC based on the dimming signal SC output from the dimming instruction receiving unit 9. Is changed according to the dimming signal SC.

  Since other configurations are the same as those of the discharge lamp lighting device 2 shown in FIG. 1, the description thereof is omitted, and the characteristic points of the present embodiment will be described below. The second feedback circuit 82a includes, for example, an AD converter 821, a DA converter 822, an unillustrated CPU (Central Processing Unit), and the like. When the CPU executes a predetermined control program, the error detection unit 823, It functions as an amplifying unit 824, an integrating unit 825, a limiter unit 826, and an adding unit 827.

  Next, the operation of the discharge lamp lighting device 2a configured as described above will be described. First, the AD converter 821 converts the detection voltage Vk into a digital value and outputs it to the error detection unit 823. In addition, the dimming instruction receiving unit 9 outputs the dimming signal SC to the error detecting unit 823 as the dimming command value Vla # DC. Then, the error detection unit 823 calculates the difference between the detection voltage Vk and the dimming command value Vla # DC and outputs the difference to the amplification unit 824.

  Next, the difference obtained by the error detection unit 823 is amplified by the amplification unit 824 with the amplification factor K corresponding to the dimming signal SC from the dimming instruction receiving unit 9 and output to the integration unit 825. In this case, the amplification unit 824 increases or decreases the amplification factor K in accordance with the increase or decrease in the dimming ratio (second instruction signal value) indicated by the dimming signal SC, that is, the amount of light emitted from the discharge lamp FL. Then, the difference value amplified by the amplifying unit 824 is integrated by the integrating unit 825, the upper and lower limits of the integrated value are clamped by the limiter unit 826, and the clamped integrated value is added to the dimming signal SC by the adding unit 827. Based on the command value Wla of the output power of the inverter circuit 6 based thereon, the added value is output as a feedback command value to the non-inverting input terminal of the operational amplifier OP1 in the first feedback circuit 81 via the DA converter 822.

  On the other hand, in the discharge lamp lighting device 2 shown in FIG. 2, as shown in FIG. 3, the equivalent impedance of the discharge lamp FL increases exponentially as the dimming ratio decreases. When the luminous flux is low, for example, the oscillation condition in the feedback control such that the gain in the feedback loop is 1 or more and the phase shift of the feedback loop is 360 degrees or more is established, and the control unit 8 controls the on / off frequency of the inverter circuit 6. Is unstable, the amount of power supplied to the discharge lamp FL becomes unstable, and the discharge lamp FL may flicker. In this case, if the amplification factor K is reduced, flickering in the low light flux region where the dimming ratio is low can be avoided, but the response speed of feedback control is slow in the high light flux region where the change in equivalent impedance of the discharge lamp FL is gentle. turn into. Therefore, the response speed of the feedback control changes depending on the dimming ratio, and there is a disadvantage that smooth dimming transient change may not be performed.

  However, according to the discharge lamp lighting device 2a shown in FIG. 6, the amplification unit 824 increases or decreases the dimming ratio (second instruction signal value) indicated by the dimming signal SC, that is, increases or decreases the light emission amount of the discharge lamp FL. Therefore, the gain K is reduced in the low light flux region where the dimming ratio is low, the oscillation of the feedback control is suppressed, and the flickering of the discharge lamp FL can be avoided. In the high light flux region, the amplification factor K is increased and the response speed of feedback control is improved, so that a substantially constant response speed can be obtained regardless of the dimming ratio.

  As a result, a substantially constant feedback response speed can be obtained regardless of the dimming ratio of the discharge lamp FL, and the light output can be smoothly changed during a transient change of the dimming ratio while suppressing feedback oscillation. it can.

(Third embodiment)
Next, a discharge lamp lighting device according to a third embodiment of the present invention will be described. FIG. 7 is a circuit diagram showing an example of the configuration of a discharge lamp lighting device 2b according to the third embodiment of the present invention. In the discharge lamp lighting device 2b shown in FIG. 7 and the discharge lamp lighting device 2a shown in FIG. 6, the amplification unit 824a in the second feedback circuit 82b of the control unit 8b has a large amount of light emission in the discharge lamp FL, that is, the discharge lamp FL. The difference is that the amplification factor K is increased or decreased in accordance with the increase or decrease of the impedance. In this case, since the increase or decrease in impedance in the discharge lamp FL corresponds to the increase or decrease in the detection voltage Vk, the amplifying unit 824a increases or decreases the amplification factor K according to the increase or decrease in the detection voltage Vk. Since the other configuration is the same as that of the discharge lamp lighting device 2 shown in FIG.

  In the discharge lamp lighting device 2a shown in FIG. 6, when the dimming instruction received by the dimming instruction receiving unit 9 changes and the dimming signal SC changes, the discharge lamp FL of the discharge lamp FL changes in the transition period in the change of the dimming signal SC. The optical output changes with a delay from the change of the dimming signal SC due to a response delay of the feedback control in the control unit 8a. For this reason, when the amplification factor K is changed according to the dimming signal SC, the transient change of the amplification factor K changes faster than the change of the equivalent impedance of the discharge lamp FL. For this reason, excess or deficiency in the change of the amplification factor K occurs during the transition period in which the dimming signal SC changes, and the time until the feedback system reaches a stable state increases. Therefore, the light of the discharge lamp FL during the transient change of the dimming ratio Output change speed decreases.

  However, in the discharge lamp lighting device 2b shown in FIG. 7, the amplification unit 824a in the second feedback circuit 82b increases or decreases the amplification factor K in accordance with the increase or decrease of the impedance of the discharge lamp FL, that is, the detection voltage Vk. The amplification factor K can be changed following the impedance change of the discharge lamp FL when the dimming ratio changes transiently, and the change of the amplification factor K can be excessive or insufficient during the transient period when the dimming ratio changes. Since the time until the feedback system is stabilized is reduced, the light output change speed of the discharge lamp FL at the time of the transient change of the dimming ratio can be improved.

It is a perspective view which shows an example of the external appearance of the illuminating device which concerns on one Embodiment of this invention. It is a circuit diagram which shows an example of a structure of the discharge lamp lighting device which concerns on the 1st Embodiment of this invention. It is a graph which shows the relationship between the light control ratio of a discharge lamp, and the lamp | ramp equivalent resistance value which is the impedance of a discharge lamp. It is a wave form diagram which shows the voltage waveform at the time of the low light beam light control which generate | occur | produces at the both ends of the discharge lamp FL in the discharge lamp lighting device shown in FIG. It is explanatory drawing for demonstrating operation | movement of the discharge lamp lighting device shown in FIG. It is a circuit diagram which shows an example of a structure of the discharge lamp lighting device which concerns on the 2nd Embodiment of this invention. It is a circuit diagram which shows an example of a structure of the discharge lamp lighting device which concerns on the 3rd Embodiment of this invention. It is a circuit diagram which shows the structure of the discharge lamp lighting device which concerns on background art. (A) is a figure which shows the relationship between a light control ratio and a lamp electric current, (b) is a light control ratio and lamp electric power.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Illuminating device 2, 2a, 2b Discharge lamp lighting device 3 Housing | casing 4 Socket 5 Chopper circuit 6 Inverter circuit 7 Load circuit 8, 8a, 8b Control part 9 Dimming instruction | indication reception part 10 VOC
DESCRIPTION OF SYMBOLS 11 Inverter drive circuit 12, 13 Command value voltage generation circuit 81 1st feedback circuit 82, 82a, 82b 2nd feedback circuit 821 AD converter 822 DA converter 823 Error detection part 824, 824a Amplification part 825 Integration part 826 Limiter part 827 Adder part C1 to C5 Capacitor D1 Diode DB Diode bridge f1 Filament f2 Filament FL Discharge lamp L1 and L2 Inductor OP1 and OP2 Operational amplifiers Q1 to Q3 Switching elements R1 to R7 Resistance

Claims (7)

A power supply unit for supplying high-frequency power to the discharge lamp to emit light, a dimming instruction receiving unit for receiving a dimming instruction for instructing the light emission amount of the discharge lamp, and the dimming received by the dimming instruction receiving unit A discharge lamp lighting device comprising a control unit for controlling a power supply amount by the power supply unit according to an instruction,
The controller is
A power detection unit for detecting the amount of power supplied from the power supply unit to the discharge lamp;
A first feedback control unit that controls the amount of power supplied by the power supply unit based on the amount of power detected by the power detection unit and the dimming instruction received by the dimming instruction receiving unit;
An impedance detector for detecting the impedance of the discharge lamp;
A second feedback control unit that controls the amount of power supplied by the power supply unit based on the impedance detected by the impedance detection unit and the dimming instruction received by the dimming instruction receiving unit;
With
The first feedback control unit mainly controls the power supply amount when the power supply amount is greater than or equal to a predetermined power supply amount set in advance, while the second feedback control unit The discharge lamp lighting device characterized in that the power supply amount is mainly controlled when the power supply amount is less than the predetermined power supply amount set in advance.   The impedance detector includes a DC voltage superimposing unit that superimposes a DC voltage on the discharge lamp according to the impedance of the discharge lamp, and determines the impedance of the discharge lamp based on the DC voltage superimposed on the discharge lamp. 2. The discharge lamp lighting device according to claim 1, wherein the discharge lamp lighting device detects the discharge lamp. The first feedback control unit includes a signal value of a power amount signal indicating the amount of power detected by the power detection unit, and a first instruction signal value representing a dimming instruction received by the dimming instruction receiving unit. To control the amount of power supplied by the power supply unit to reduce the difference between
The second feedback control unit amplifies a difference between a signal value indicating the impedance detected by the impedance detection unit and a second instruction signal value indicating the dimming instruction received by the dimming instruction receiving unit. Then, by adding to the first instruction signal value, the amount of power supplied by the power supply unit is controlled to reduce the difference between the signal value representing the impedance and the second instruction signal value. The discharge lamp lighting device according to claim 1 or 2, characterized in that.   The discharge lamp according to any one of claims 1 to 3, wherein the second feedback control unit increases or decreases the difference amplification factor according to the amount of light emission in the discharge lamp. Lighting device.   The second feedback control unit is configured to increase or decrease the amplification factor of the difference in accordance with an increase or decrease in light emission amount in the discharge lamp represented by the second instruction signal value. 5. The discharge lamp lighting device according to 4.   5. The discharge lamp lighting device according to claim 4, wherein the second feedback control unit is configured to increase or decrease the amplification factor of the difference in accordance with an increase or decrease of the impedance detected by the impedance detection unit. A discharge lamp lighting device for lighting a discharge lamp, a housing for housing the discharge lamp lighting device, and a socket for connecting the discharge lamp to the discharge lamp lighting device,
The said discharge lamp lighting device is a discharge lamp lighting device in any one of Claims 1-6, The illuminating device characterized by the above-mentioned.

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