JP2008277121A - Discharge lamp lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device 10 capable of detecting a discharge current removing effect of capacitive elements in a simple structure. <P>SOLUTION: Discharge voltage of the discharge lamp FL is detected by a discharge voltage detecting means 20. The current output from an inverter circuit 12 is detected by a current detecting means 24. A peak phase of the discharge voltage is detected by a peak phase detecting means having a detecting circuit 27, the current output from the inverter circuit 12 is detected at the peak phase of the discharge voltage, and the discharge current removing the effect of capacitive elements is detected. Thus, the inverter circuit 12 can be feedback-controlled in a simple structure by the discharge current removing the effect of capacitive elements. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a discharge lamp lighting device for lighting a discharge lamp.

  Conventionally, in a discharge lamp lighting device, for example, a half-bridge type inverter circuit is used, and the discharge lamp is started and lit by this inverter circuit. If the discharge lamp has a dimming function, the discharge lamp discharge voltage and the output current output from the inverter circuit are detected in order to stably dim the discharge lamp, and these detected discharges are detected. The inverter circuit is feedback controlled using voltage and output current.

  In addition, since the discharge lamp is lit at a high frequency voltage, the output current of the inverter circuit includes a discharge current flowing in the discharge lamp, as a capacitive component, between the discharge lamp and the appliance, between the wires, the tube wall of the discharge lamp, etc. The leakage current component flowing in the capacitance generated in the capacitor is included.

  When dimming the discharge lamp using an inverter circuit, dimming is possible by increasing the oscillation frequency of the inverter circuit to reduce the output current. On the other hand, when the discharge lamp is a hot cathode fluorescent lamp, it has a negative characteristic. Therefore, when the discharge current decreases, the discharge voltage increases. For this reason, the ratio of the leakage current increases with deep dimming.

Therefore, by generating a reference phase signal from the detected discharge voltage, and detecting the output current of the inverter circuit synchronized with the reference phase signal of this discharge voltage, the discharge current excluding the influence of the leakage current component flowing in the capacitance There is a discharge lamp lighting device that detects the noise and feedback-controls the inverter circuit by this discharge current (see, for example, Patent Document 1).
Japanese Patent No. 3724594 (page 5-7, Fig. 1-4)

  As in the above-described discharge lamp lighting device, a reference phase signal is generated from the detected discharge voltage, and an output current of the inverter circuit synchronized with the reference phase signal of the discharge voltage is detected, thereby causing a leakage current flowing in the capacitance. Although it is possible to detect the discharge current excluding the influence of components, a circuit that detects the output current with reference to the phase of the discharge voltage has a problem that the configuration is complicated and the scale is increased.

  The present invention has been made in view of these points, and an object of the present invention is to provide a discharge lamp lighting device capable of detecting a discharge current with a simple configuration and excluding the influence of a capacitive component.

  The discharge lamp lighting device according to claim 1 is an inverter circuit that converts a DC voltage into a high-frequency voltage and outputs it by an operation of a switching element; a discharge voltage detection means that detects a discharge voltage of the discharge lamp; and the inverter circuit outputs Current detection means for detecting current; peak phase detection means for detecting the peak phase of the discharge voltage detected by the discharge voltage detection means; switching element of the inverter circuit based on the current detected by the current detection means in the peak phase of the discharge voltage And a control means for performing feedback control.

  Examples of the discharge lamp include, but are not limited to, a hot cathode fluorescent lamp and a high pressure discharge lamp.

  The inverter circuit may be either a half bridge type or a full bridge type as long as it can convert a DC voltage into a high frequency voltage by an operation of a switching element such as a field effect transistor.

  As the peak phase detection means, any means may be used as long as the peak phase of the discharge voltage detected by the discharge voltage detection means can be detected. The peak phase indicates the maximum value or the minimum value of the sinusoidal discharge voltage.

  Then, the peak phase of the discharge voltage of the discharge lamp is detected, and the current output from the inverter circuit is detected at the peak phase of the discharge voltage, thereby detecting the discharge current excluding the influence of the capacitive component. The inverter circuit is feedback controlled by the discharge current excluding the influence of this capacitive component.

  The discharge lamp lighting device according to claim 2 is the discharge lamp lighting device according to claim 1, wherein the peak phase detection means has the discharge voltage detected by the discharge voltage detection means reaching a predetermined reference value. An intermediate point in the period is detected as a peak phase.

  Whether or not the discharge voltage has reached a predetermined reference value can be determined by using a comparison means such as a comparator, for example.

  A discharge lamp lighting device according to claim 3 is the discharge lamp lighting device according to claim 1, further comprising a resonance circuit having a resonance inductance and a resonance capacitor for applying a voltage according to the output of the inverter circuit to the discharge lamp, and having a peak. The phase detection means detects the peak phase of the discharge voltage in synchronization with the voltage change across the resonance capacitor of the resonance circuit connected in parallel with the discharge lamp.

  This is because, for example, by using a time constant circuit of a resistor and a capacitor for the detection circuit that detects the voltage across the resonant capacitor, the rise and fall of the voltage are determined by the time constant of the resistor and the capacitor, and the voltage Since the falling edge of the signal becomes the peak phase of the discharge voltage, the peak phase of the discharge voltage can be detected by detecting the detection of the falling edge. The falling edge can be detected by using a comparison circuit. When a digital control element is used, it can be input to the I / O port and judged by software.

  A discharge lamp lighting device according to claim 4 is the discharge lamp lighting device according to claim 1, further comprising a resonance circuit having a resonance inductance and a resonance capacitor for applying a voltage according to the output of the inverter circuit to the discharge lamp, and having a peak. The phase detection means detects the peak phase of the discharge voltage in synchronization with the current flowing through the resonance capacitor of the resonance circuit connected in parallel with the discharge lamp being substantially zero.

  This is because the current flowing through the resonant capacitor becomes substantially zero at the peak phase of the discharge voltage. This substantially zero includes both cases of 0 and close to 0, and even if slightly deviated from 0, detection is not hindered.

  The discharge lamp lighting device according to claim 5 is the discharge lamp lighting device according to claim 1, wherein the peak phase detecting means is a maximum value of values obtained by sampling the discharge voltage detected by the discharge voltage detecting means at a predetermined cycle, and One of the minimum values is detected as a peak phase.

  For sampling, for example, a sample / hold circuit for sampling the discharge voltage and an analog / digital converter for digitizing the sampling value are used.

  According to the discharge lamp lighting device of the first aspect, the peak phase of the discharge voltage of the discharge lamp is detected, and the current output from the inverter circuit is detected at the peak phase of the discharge voltage. Since the removed discharge current can be detected, the inverter circuit can be feedback-controlled with the discharge current excluding the influence of the capacitive component with a simple configuration.

  According to the discharge lamp lighting device of the second aspect, in addition to the effect of the discharge lamp lighting device of the first aspect, an intermediate point in a period in which the discharge voltage of the discharge lamp reaches a predetermined reference value is obtained. Since the peak phase is detected, the peak phase of the discharge voltage can be detected with a simple configuration.

  According to the discharge lamp lighting device of claim 3, in addition to the effect of the discharge lamp lighting device of claim 1, in synchronization with the voltage change across the resonant capacitor of the resonant circuit connected in parallel with the discharge lamp. Since the peak phase of the discharge voltage is detected, the peak phase of the discharge voltage can be detected with a simple configuration.

  According to the discharge lamp lighting device of claim 4, in addition to the effect of the discharge lamp lighting device of claim 1, when the current flowing through the resonance capacitor of the resonance circuit connected in parallel with the discharge lamp becomes substantially zero Since the peak phase of the discharge voltage is detected in synchronization with the above, the peak phase of the discharge voltage can be detected with a simple configuration.

  According to the discharge lamp lighting device according to claim 5, in addition to the effect of the discharge lamp lighting device according to claim 1, any one of a maximum value and a minimum value of values obtained by sampling the discharge voltage of the discharge lamp at a predetermined cycle. Since one is detected as the peak phase, the peak phase of the discharge voltage can be detected with a simple configuration.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a configuration diagram of a discharge lamp lighting device, FIG. 2 is a waveform diagram showing the relationship between the discharge voltage, discharge current, and leakage current of the discharge lamp lighting device, and FIG. The first detection method for detecting the peak phase is shown, (a) is a waveform diagram of the shaped discharge voltage, (b) is a waveform diagram of the output of the comparator, and FIG. 4 is a diagram of the discharge voltage of the discharge lamp lighting device. FIG. 5 is a circuit diagram showing a second detection method for detecting the peak phase, FIG. 5 shows the second detection method, (a) is a waveform diagram of the voltage of the resonant capacitor detected by the voltage detection circuit, and (b). Is a waveform diagram of the discharge voltage, FIG. 6 is a circuit diagram showing a third detection method for detecting the peak phase of the discharge voltage in the discharge lamp lighting device, FIG. 7 shows the third detection method, ) Is a waveform diagram of the current detected by the current detection circuit, and (b) is the current flowing through the resonant capacitor. Fig. 8 (c) is a waveform diagram of the discharge voltage, Fig. 8 shows a fourth detection method for detecting the peak phase of the discharge voltage with the discharge lamp lighting device, and (a) is a waveform of the discharge voltage and the discharge current. FIG. 9B is a waveform diagram obtained by sampling the discharge voltage and the discharge current, FIG. 9 shows the fourth detection method, FIG. 9A is a waveform diagram of the discharge voltage and the discharge current, and FIG. It is the wave form diagram which sampled the discharge current, and FIG. 10 is a perspective view of the lighting fixture to which the discharge lamp lighting device is applied.

  As shown in FIG. 1, the discharge lamp lighting device 10 has a commercial power source e connected to an input terminal of a full-wave rectifying element REC that rectifies a commercial power supply voltage, and a direct current rectified to the output terminal of the full-wave rectifying element REC. A booster circuit 11 that boosts the voltage is connected. A capacitor C1 is connected between the output terminals of the booster circuit 11, and an inverter circuit 12 that converts a DC voltage into a high-frequency voltage and outputs it is connected. This inverter circuit 12 is a half-bridge type inverter and has field effect transistors Q1 and Q2 as two switching elements connected in series. A DC cutting capacitor C2 and a resonance circuit 13 having a resonance inductance L1 and a resonance capacitor C3 are connected to both ends of the field effect transistor Q2. A discharge lamp FL such as a hot cathode fluorescent lamp is connected in parallel with the resonant capacitor C3. The heating means for heating the filament of the discharge lamp FL is omitted in the drawing.

  A control circuit 16 is connected to the gates of the field effect transistors Q1 and Q2 as control means for controlling the on / off operation of the field effect transistors Q1 and Q2.

  Further, a voltage dividing circuit 19 composed of a pair of resistors R1 and R2 is connected to both ends of the resonant capacitor C3, and the voltage dividing circuit 19 constitutes a discharge voltage detecting means 20 for detecting the discharge voltage of the discharge lamp FL. Yes.

  A detection winding 23 is connected to one end of the resonance capacitor C3, and current detection means 24 for detecting a current output from the inverter circuit 12 (hereinafter referred to as an output current) is configured by the detection winding 23.

  The discharge voltage detection means 20 and the current detection means 24 are connected to a detection circuit 27 having a function of a peak phase detection means for detecting the peak phase of the discharge voltage detected by the discharge voltage detection means 20. The function of the peak phase detecting means may be provided in the control circuit 16. Here, the peak phase of the discharge voltage refers to the maximum value or the minimum value of the sinusoidal discharge voltage.

  The control circuit 16 has a function of performing feedback control of the inverter circuit 12 based on the output current of the inverter circuit 12 detected by the current detection means 24 in the peak phase of the discharge voltage detected by the peak phase detection means, and input dimming It has a function of controlling the dimming level corresponding to the signal.

  As shown in FIG. 2, at the position of the peak phase of the discharge voltage VL, for example, the leakage current component is capacitive as a capacitive component, so it can be considered to be substantially zero, and only the discharge current IL is detected. Since the output current is the sum of the discharge current IL and the leakage current, the leakage current component is substantially zero at the peak phase position of the discharge voltage VL. By detecting the output current at the peak phase of the discharge voltage VL, it is possible to detect only the discharge current IL with a simple configuration, and the inverter circuit 12 can be feedback controlled by this discharge current IL, which is stable even during deep dimming Lighting can be obtained.

  Next, a first detection method for detecting the peak phase of the discharge voltage by the peak phase detection means will be described with reference to FIG.

  This first detection method is a method of detecting the peak phase from the discharge voltage VL detected by the discharge voltage detection means 20.

  The discharge voltage VL detected by the discharge voltage detection means 20 has a waveform as shown in FIG. At this time, the voltage reference value Vth is determined and shaped into a waveform as shown in FIG. Since the discharge voltage VL is substantially sinusoidal, the peak point of the discharge voltage VL is the middle point of the period when the output of the comparator is high.

  For example, the period T_VL during which the output of the comparator is at a high level with the pulse of the first discharge voltage VL is measured, and the time period T_VL / 2 from the rising edge of the output of the comparator is measured during the pulse of the second discharge voltage VL. The peak phase can be obtained.

  By detecting the output current at this peak phase, only the discharge current IL excluding the leakage current component can be detected.

  Next, a second detection method for detecting the peak phase of the discharge voltage by the peak phase detection means will be described with reference to FIG. 4 and FIG.

  This second detection method shows a method of detecting the peak phase of the discharge voltage VL using the voltage across the resonance capacitor C3.

  As shown in FIG. 4, in the basic circuit configuration shown in FIG. 1, a voltage detection circuit for detecting the voltage across the resonance capacitor C3 is added. In this voltage detection circuit, a series circuit of a capacitor C and a diode D1 is connected in parallel with the resonance capacitor C3, and a connection point 31 between the capacitor C and the diode D is constituted by a resistor R3 and a capacitor C5 via the diode D. A time constant circuit is connected.

  A voltage CrV_det as shown in FIG. 5A is generated at the connection point 31 between the capacitor C and the diode D1. FIG. 5 (b) also shows the waveform of the discharge voltage VL. At this time, the voltage CrV_det rises with the time constant of the resistor R3 and the capacitor C5, the fall time is determined, and this falling edge becomes the peak phase of the discharge voltage VL.

  Therefore, only the discharge current IL excluding the leakage current component can be detected by detecting the output current in synchronization with the falling edge.

  Note that the edge can be detected by using a comparison circuit, and when a digital control element is used, it can be input to the I / O port and judged by software. Further, since the discharge voltage VL and the voltage across the resonant capacitor C3 are substantially the same, the method for detecting the peak phase of the discharge voltage VL used here can be used for both.

  Next, a third detection method for detecting the peak phase of the discharge voltage by the peak phase detection means will be described with reference to FIGS.

  In this third detection method, a method of detecting the peak phase of the discharge voltage VL using the current flowing through the resonance capacitor C3 is shown.

  As shown in FIG. 6, in the basic circuit configuration shown in FIG. 1, a current detection circuit for detecting the current of the resonant capacitor C3 is added. In this current detection circuit, a resistor R4 is connected in series with the resonance capacitor C3, and a diode D3, a diode D4, and a resistor R5 are connected in parallel with the resistor R4.

  As shown in FIG. 7, the current flowing through the resonant capacitor C3 takes substantially zero at the peak phase of the discharge voltage VL. At this time, the voltage CrC_det at the connection point 34 between the diode D and the resistor of the current detection circuit is generated at the point where the current of the resonance capacitor C3 crosses zero, so by detecting the output current in synchronization with this point, Only the discharge current IL excluding the leakage current component can be detected.

  Note that in order to detect the peak phase of the discharge voltage VL using the current flowing through the resonant capacitor C3, a comparator may be used to shape the waveform like the CrV_det waveform shown in FIG. In this case, the comparator needs to be faster due to the operation of the load, and if the processing is not performed within a quarter cycle of the frequency that requires control, the current direction is reversed and the value cannot be accurately obtained. A comparator having a relationship of: <response time <(operation period at feedback control / 4) − (time from detection to data acquisition) is used.

  Next, a fourth detection method for detecting the peak phase of the discharge voltage by the peak phase detection means will be described with reference to FIGS.

  The detected values of the discharge voltage and the output current are analog signals. The detection circuit 27 (or control circuit 16) shown in FIG. 1 is provided with sampling means for discretely sampling the analog signals of the discharge voltage and the output current to obtain values at each sampling point. it can. As such sampling means, means comprising a sample / hold circuit and an A / D (analog / digital) converter is widely used. When analog signals of the discharge voltage and output current are detected by this means, sampling values that are discrete in time can be converted into numerical values. That is, the analog signal can be changed to a form in which the numerical value can be calculated by a calculation means such as a CPU.

  FIGS. 8A and 8B are conceptual diagrams in the case of sampling the analog signal of the discharge voltage. For the sake of simplicity, it is assumed that the target is the discharge voltage VL and the discharge current IL, and that the negative potential is not generated under an arbitrary offset. When each analog signal passes through the sample / hold circuit and the A / D converter, the analog signal can be converted into a discrete amount sampled at the set sampling period Ts. At this time, the signals of the discharge voltage VL and the discharge current IL are {v [0], v [1], v [2], ...}, {i [0], i [1], i [2], ...} can be expressed as a set of discrete quantities. Since each value is digitized, a comparison operation or an arithmetic operation can be performed. Theoretically, if the frequency of the signal to be sampled is fsignal, if the sampling frequency fs (= 1 / Ts) has a relationship of fs> 2 * fsignal, the original signal can be reproduced from a discrete quantity. By performing complementation, the original detection signal can be reproduced.

  Here, in order to know the peak phase of the discharge voltage VL, a discretized value as shown in FIG. 8B is used. When the sampled values are sequentially compared as shown in FIG. 8B, v [0] <v [1] <v [2] <v [3]> v [4]> v [5]. . Using this, it can be seen that v [3] is the peak phase of the discharge voltage VL. From this, it can be seen that i [3] of the discharge current IL corresponding to the peak phase v [3] of the discharge voltage VL gives the discharge current IL synchronized with the peak phase of the discharge voltage VL. In this way, the analog signal of the discharge voltage VL is discretely sampled to detect the peak phase of the discharge voltage VL, and the output current is detected in synchronization with the peak phase of the discharge voltage VL. Only the excluded discharge current IL can be easily detected.

  FIG. 9 shows how the discharge current IL is detected in the actual circuit configuration. FIG. 9A shows waveforms of the discharge voltage VL and the input current of the output current of the inverter circuit 12 to the sample / hold circuit. FIG. 9B shows a sample result obtained through the A / D converter. Then, the detected discharge voltage VL and the output current of the inverter circuit 12 are input to the sample / hold circuit as a rectified waveform. Further, at the time of dimming, as shown in FIG. 9, the output current has a leading phase with respect to the waveform of the discharge voltage VL. At this time, v [0] <v [1] <v [2] <v [3]> v [4] is determined by using the calculation means, and the phase v [3] is the peak phase of the discharge voltage VL. Can know. I [3] which is the value of the output current of the inverter circuit 12 in this phase information corresponds to the peak phase of the discharge current IL.

  Here, the discharge voltage VL and the output current of the inverter circuit 12 are sampled simultaneously and independently, so that there is no deviation between the peak phase of the discharge voltage VL and the peak phase of the discharge current IL. Although it is desirable to have an independent sample / hold circuit and A / D converter for each detection amount as a circuit configuration, the discharge voltage VL is one circuit having the sample / hold circuit and the A / D converter. By repeating the determination of the peak phase, the acquisition of phase information, and the detection of the peak phase of the discharge current IL, sampling can be performed substantially simultaneously.

  In addition, the circuit configuration can be simplified by using a microcomputer or DSP (digital signal processor) incorporating a sample / hold circuit and an A / D converter as a control element.

  By detecting the peak phase of the discharge voltage VL by the above detection methods, and detecting the output current of the inverter circuit 12 at the peak phase of the discharge voltage VL, only the discharge current IL excluding the influence of the leakage current component is obtained. It can be detected. Therefore, the inverter circuit 12 can be feedback-controlled by the discharge current IL excluding the influence of the leakage current component with a simple configuration.

  The discharge lamp lighting device 10 thus configured can be applied to a lighting fixture as shown in FIG. This lighting fixture includes a fixture main body 41 in which the discharge lamp lighting device 10 is disposed, sockets 42 on which both ends of the fixture main body 41 are mounted with straight tube-type discharge lamps FL, and the like.

It is a block diagram of the discharge lamp lighting device which shows one embodiment of this invention. It is a wave form diagram which shows the relationship between the discharge voltage, discharge current, and leakage current of a discharge lamp lighting device same as the above. The 1st detection method which detects the peak phase of discharge voltage with a discharge lamp lighting device same as the above is shown, (a) is the waveform figure of the shaped discharge voltage, (b) is the waveform figure of the output of a comparator. It is a circuit diagram which shows the 2nd detection method which detects the peak phase of discharge voltage with a discharge lamp lighting device same as the above. The second detection method is shown, wherein (a) is a waveform diagram of the voltage of the resonant capacitor detected by the voltage detection circuit, and (b) is a waveform diagram of the discharge voltage. It is a circuit diagram which shows the 3rd detection method which detects the peak phase of discharge voltage with a discharge lamp lighting device same as the above. The third detection method is shown, wherein (a) is a waveform diagram of the current detected by the current detection circuit, (b) is a waveform diagram of the current flowing through the resonant capacitor, and (c) is a waveform diagram of the discharge voltage. The fourth detection method for detecting the peak phase of the discharge voltage by the discharge lamp lighting device is shown. (A) is a waveform diagram of the discharge voltage and discharge current, and (b) is a waveform diagram obtained by sampling the discharge voltage and discharge current. is there. The fourth detection method is shown, wherein (a) is a waveform diagram of the discharge voltage and discharge current, and (b) is a waveform diagram obtained by sampling the discharge voltage and discharge current. It is a perspective view of the lighting fixture to which the same discharge lamp lighting device is applied.

Explanation of symbols

10 Discharge lamp lighting device
12 Inverter circuit
13 Resonant circuit
16 Control circuit as control means
20 Discharge voltage detection means
24 Current detection means
27 Detection circuit as peak phase detection means
C3 resonant capacitor
FL discharge lamp
Q1, Q2 Field effect transistors as switching elements

Claims (5)

An inverter circuit that converts a DC voltage into a high-frequency voltage by the operation of the switching element;
Discharge voltage detecting means for detecting the discharge voltage of the discharge lamp;
Current detection means for detecting current output from the inverter circuit;
Peak phase detection means for detecting the peak phase of the discharge voltage detected by the discharge voltage detection means;
Control means for feedback-controlling the switching elements of the inverter circuit with the current detected by the current detection means in the peak phase of the discharge voltage;
A discharge lamp lighting device comprising: The discharge lamp according to claim 1, wherein the peak phase detecting means detects, as a peak phase, an intermediate point in a period in which the discharge voltage detected by the discharge voltage detecting means reaches a predetermined reference value. Lighting device. Comprising a resonance circuit having a resonance inductance and a resonance capacitor for applying a voltage according to the output of the inverter circuit to the discharge lamp;
2. The discharge lamp lighting device according to claim 1, wherein the peak phase detection means detects the peak phase of the discharge voltage in synchronization with a voltage change at both ends of the resonance capacitor of the resonance circuit connected in parallel with the discharge lamp. . Comprising a resonance circuit having a resonance inductance and a resonance capacitor for applying a voltage according to the output of the inverter circuit to the discharge lamp;
The peak phase detection means detects the peak phase of the discharge voltage in synchronization with the current flowing through the resonance capacitor of the resonance circuit connected in parallel with the discharge lamp being substantially zero. Discharge lamp lighting device. The peak phase detection means detects either one of a maximum value and a minimum value of values obtained by sampling the discharge voltage detected by the discharge voltage detection means at a predetermined cycle as a peak phase. Discharge lamp lighting device.

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