CN1049305C - Power supply apparatus having high power-factor and low distortion-factor characteristics - Google Patents

Abstract

A rectifier device can commutate the input voltage of the AC power supply. The first and second switch device is arranged between a pair of output terminals of the rectifier device and can alternatively break-over/cut-off. The series-wound circuit of the first capacitor and inductor is arranged between the two ends of one of the first and the second switch device, to operate the output frequency of the rectifier device smoothly. The second capacitor forms a resonance circuit with the inductor together according to the break-over/cut-off operation of first and second switch. The capacitance of the second capacitor is less than the capacitance of the first capacitor.

Description

Discharge lamp lighting device with high power factor and low distortion coefficient characteristics

The invention relates to a lighting device for a discharge lamp, which improves the input factor of an AC power supply, reduces the distortion of the input current, and suppresses harmonic components.

A device having the arrangement disclosed in Japanese Patent Application KOKA1 Publication No. 5-174986 is a known conventional discharge lamp lighting device of this type.

In the discharge lamp lighting device disclosed in Japanese Patent Application KOKA1 Publication No. 5-174986, a half-bridge inverter circuit with two series-connected switching elements is connected to the full-wave rectifier, for industrial AC power supply To rectify the voltage, connect a series circuit of a load circuit with an inductor and a DC blocking capacitor to a switching element in the inverter circuit.

Such a discharge lamp lighting device disclosed in Japanese Patent Application KOKA1 Publication No. 5-174986 will be described as prior art 1 below.

In the prior art, as shown in FIG. 50 , a coil 273 and a capacitor 274 are arranged on the input side of a full-wave rectifier 272 for rectifying the output voltage of a commercial AC power supply 271 . A capacitor 275 whose time constant is set within a certain range is arranged on the output side of the full-wave rectifier 272 . A half-bridge type inverter circuit 278 having two switching elements 276 and 277 connected in series is connected to the capacitor 275 between the full-wave rectifiers 272 in parallel connection. A series circuit of an inductor 279 , a discharge lamp 280 and a DC blocking capacitor 281 is connected to a switching element 277 of an inverter circuit 278 .

The effect of this prior art 1 is not described in detail here. However, its effect can be measured from the accompanying description of purpose and timing chart, etc.

The capacitor 275 on the output side of the full-wave rectifier 272 smoothes the frequency of the AC power source 271 to a certain extent. At the same time, the coil 273 and the capacitor 274 on the input side of the full-wave rectifier 272 generate a resonance voltage. This resonance voltage is generated in synchronization with the switching cycle of the switching element 276 of the half-bridge inverter circuit 278 . During the conduction period of the switching element 276, power is first supplied from the capacitor 275 to the inverter circuit 278, but since the capacity of the capacitor 275 is set to be small, a voltage drop occurs. Thereafter, current flows from the commercial AC power source 271 to the inverter circuit 278 . When the switching element 276 is turned off, the inflow current is cut off, and the above-mentioned resonant voltage is generated. If the circuit constant defined by the coil 273 and the capacitor 274 is set within a predetermined range, the resonance voltage can be made higher than the voltage across the capacitor 275 having a smoothing effect. Therefore, since the resonance voltage is used as a power source, current flows into the capacitor 275 . In this operating condition, input current flows even during periods of low input AC voltage, resulting in high input power factor and reduced input current distortion.

The device in Japanese Patent Application KOKA1 Publication No.: 2-75200 (hereinafter referred to as prior art 2) is another known conventional device.

As shown in FIG. 51, the device includes a pair of switching devices 285 and 286 disposed between the output terminals of a rectifier 284 for receiving an output from an AC power source 282 via a high frequency isolator 283. Diodes 287 and 288 for supplying reverse current are connected in parallel to switching devices 285 and 286 . Two series capacitors 289 and 290 are connected in parallel to switching devices 285 and 286 . The capacity of the capacitor 290 is set larger than the other capacitor 289 . A diode 291 is connected in parallel to a capacitor 289 having a relatively small capacitance. A series circuit of an inductor 292 and a discharge lamp 293 is connected between the node of a pair of switching elements 285 and 286 and the node of capacitors 289 and 290 . In addition, a capacitor 294 is connected between both ends of the filament of the discharge lamp 293 .

According to prior art 2, during the conduction period of switching device 285, the output of rectifier 284 is used to pass current through switching device 285 and to supply inductor 292 and discharge lamp 293, and to charge capacitor 290 with a larger capacity. Energy stored in inductor 292 is used to provide current to capacitor 290 and diode 288 during the period between switching device 285 is off and the other switching device 286 is on. When switching device 286 is turned on, the charge on capacitor 290 is discharged through switching device 286 , inductor 292 and discharge lamp 293 . During the next period between switching device 286 being turned off and the other switching device 285 being turned on, energy stored in inductor 292 is used to provide current to smaller capacitor 289 and diode 287 .

In this manner, a high-frequency alternating current flows in the discharge lamp 293 . Moreover, during the conduction period of the switching device 285, the current charges the capacitor 290 with a larger capacity, making the input current close to a sine wave.

However, in prior art 1, it seems difficult to perform sufficient smooth operation; or sufficiently reduce input current distortion. This is because the current flowing from the AC power source 271 into the inverter circuit 278 near the zero cross point of the AC power source 271 is zero or very small, and a high resonance voltage cannot be obtained. More specifically, if the capacitor 275 is to perform a sufficient smooth operation but cannot supply current near the zero cross point of the AC power source 271, a high resonance voltage cannot be obtained for the above-mentioned reason. During this period, AC voltage 271 cannot provide input current. Therefore, input AC distortion cannot be sufficiently reduced. If the voltage of the capacitor 275 drops near the zero-crossing point of the AC power supply 271, a sufficient smooth voltage cannot be obtained. As described above, in prior art 1, if the circuit constants are set so as to reduce input current distortion, the circuit cannot sufficiently smooth the input voltage. Therefore, the fluctuation of the lamp current is increased, so that the luminous efficiency is lowered, or the fluctuation of light is increased.

In addition, according to prior art 1, when a resonance voltage is generated, a high-frequency ripple voltage appears on the AC power supply side. Therefore, in addition to the inductor 273 and capacitor 274, a dedicated filter is required to reduce the ripple voltage.

According to prior art 2, when the output voltage of the rectifier 284 is at a peak value (when the pulsating output voltage of the rectifier 284 is zero or close to zero), the input current cannot be supplied. During this time, the charge on the larger capacitor 290 is discharged. Therefore, during this period, only the discharge current of the capacitor 29 flows through the diode 291 together with the regenerative current generated based on the discharge current and the energy stored in the inductor 292 . This phenomenon occurs for the following reasons. Therefore, the voltage across the series circuit of capacitors 289 and 290 is greater than the output voltage of rectifier 284 during this period. As described above, according to the prior art 2, the commercial power supply 282 (rectifier 284) cannot supply the input current during certain periods, and as a result, the input current distortion cannot be sufficiently reduced.

The present invention is to solve the above problems, and its purpose is to provide a new and improved discharge lamp lighting device, which reduces the fluctuation of the output current by smoothing the input voltage, improves the input power factor, and reduces the input current. Harmonics in .

Another object of the present invention is to provide a discharge lamp lighting device, which, on the basis of the above-mentioned improved discharge lamp lighting device, uses a relatively simple structure to reliably control the resonance voltage, such as making the peak value of the resonance voltage constant .

Still another object of the present invention is to provide a discharge lamp lighting device which can reliably reduce input current distortion in addition to the above effects.

According to a first aspect of the present invention, there is provided a lighting device for a discharge lamp, comprising a rectifying device for rectifying an output voltage of an AC power source to output an unsmoothed DC voltage, and being arranged in series between output terminals of the rectifying device , the first and second switching devices alternately turned on and off at a frequency higher than the output frequency of the rectifying device, and the first smoothing capacitor arranged in parallel with the first switching device, further comprising: An inductor between the first switching device and the first capacitor; a second capacitor arranged in series with the inductor, corresponding to the on-off of the first and second switches, and synergistically resonant with the inductor ; and a discharge lamp provided in parallel with the inductor and supplied with high-frequency power.

According to the invention, for example, field effect transistors can be used as switching devices. In this case, the parasitic diode that must be included due to the structure of the field effect transistor can be used to pass the reverse current. On the other hand, the switching device can also be mainly constituted by a switching element not including a parasitic diode between the collector and the emitter, such as a bipolar transistor. In this case, a diode is connected in parallel between the collector and the emitter, opposite to its conduction direction. However, if a diode is connected between the emitter and the base due to the structure of the base circuit of the transistor, the diode can be used to allow reverse current to flow.

In addition, in the present invention, according to the above description, the switching devices are alternately turned on/off. However, during the period when one switching device goes from the on state to the off state and the other switching device goes from the off state to the on state, there may or may not be a period in which both switching devices are in the off state. The switching frequency of the switching device pair should be higher than the output frequency of the rectifier device, preferably more than a few kilohertz or higher, more preferably more than 20KHz or higher, which is higher than the audio frequency.

In the present invention, "serial connection form" or "parallel connection form" means connecting a given electronic part with or without intermediary of another electronic part.

In addition, the second capacitor forming the resonance circuit together with the inductor may be placed at any position as long as the resonance circuit can be formed. For example, the second capacitor may be connected in series to the series circuit of the second switching device and the inductor, or may be connected between the output terminals of the rectifying means. Alternatively, part or all of the second capacitor may be connected between one output terminal of the rectifying means and the pair of switching devices.

Also, in the present invention, any type of inductor can be used as long as it can resonate with the second capacitor. For example, choke coils, transformers, and the like may be used. (The above description is also applicable to the following aspects of the present invention.)

According to a second aspect of the present invention, there is provided a lighting device for a discharge lamp, comprising a rectifying device for rectifying an output voltage of an AC power supply to output an unsmoothed DC voltage, and being arranged in series between output ends of the rectifying devices , the first and second switching devices alternately turned on and off at a frequency higher than the output frequency of the rectifying device, and the first smoothing capacitor arranged in parallel with the first switching device, further comprising: An inductor between the first switching device and the first capacitor; a second capacitor arranged in series with the inductor, corresponding to the on-off of the first and second switches, and synergistically resonant with the inductor a control unit, connected to the first switching device, configured to control the conduction period of the first switching device according to the discharge current released by the first capacitor and flowing in the first switching device, to controlling the resonant voltage value generated by the inductor and the second capacitor; an output circuit for obtaining a high-frequency output based on the resonance generated by the inductor and the second capacitor; and a device arranged in parallel with the inductor , A discharge lamp to which high-frequency power is applied.

According to a third aspect of the present invention, the discharge lamp lighting device described in the first or second aspect further includes switch control means for turning on/off the first and second switching devices at a substantially constant frequency, And can change the conduction cycle rate of the switching device.

According to a fourth aspect of the present invention, the discharge lamp lighting device of the first or second aspect further includes switching device control means for turning on/off the first and second switching devices at a substantially constant frequency and capable of The conduction period rate of the switch device is changed, and the switch control device shortens the conduction period of the other switch device when the peak value of the voltage output of each half cycle of the AC power supply is large, and prolongs the conduction period when the peak value is small.

In the present invention, the conduction period of another switching device can be continuously or gradually changed according to the peak value.

According to a fifth aspect of the present invention, the discharge lamp lighting device of the first or second aspect further includes switching control means capable of changing the on/off frequencies of the first and second switching devices.

According to a sixth aspect of the present invention, in the discharge lamp lighting device of the fifth aspect, the first and second switching devices are turned on at a relatively low frequency during a period corresponding to a small peak value of the output voltage of the rectifying means. / cut off, when the peak value rises, it is turned on/off at a relatively high frequency.

According to a seventh aspect of the present invention, in the discharge lamp lighting device of one of the fifth or sixth aspects, the second capacitor is connected in parallel to the other switching device and the inductor.

According to an eighth aspect of the present invention, in the discharge lamp lighting device of one of the first to sixth aspects, the second capacitor is provided between output terminals of the rectifying means.

According to a ninth aspect of the present invention, in the discharge lamp lighting device of one of the first to sixth aspects, the second capacitor is provided between at least one output terminal of the rectifying device and the pair of switching devices, and a diode is connected in parallel to the first capacitor. On the second capacitor, its polarity is the same as the output polarity of the rectifier.

In the present invention, the second capacitor may be constituted by two or more capacitors, and these capacitors may be respectively provided between the positive output terminal and the negative output terminal of the rectifying device and the pair of switching devices. An element capable of passing a resonant current is required between the output terminals of the rectifier. For such components, capacitors that pass high-frequency waves are usually used, but special components can also be used.

According to a tenth aspect of the present invention, in the discharge lamp lighting device of the fifth or sixth aspect, an impedance circuit whose impedance decreases as frequency increases is provided in the output circuit.

According to the eleventh aspect of the present invention, in the discharge lamp lighting device of one of the first to tenth aspects, an output circuit is provided between the inductor, the power supply and the output end of the load, and the primary winding of the transformer is connected in series The form is connected to the load, and the output of the secondary winding of the transformer is used to drive and control the first and second switching devices.

According to a twelfth aspect of the present invention, the discharge lamp lighting device of one of the first to tenth aspects further includes a discharge lamp as a load.

According to a thirteenth aspect of the present invention, in the discharge lamp lighting device of the twelfth aspect, the conduction period of the second switching device is set to be longer than that of the discharge lamp during a predetermined period during which the discharge lamp is started. The conduction period during the lighting period.

According to a fourteenth aspect of the present invention, in the discharge lamp lighting device of the first to thirteenth aspects, at least the discharge lamp is mounted on the lamp as a load.

According to a fifteenth aspect of the present invention, there is provided a discharge lamp lighting device comprising rectifying devices which rectify an AC voltage and output an unsmoothed DC voltage, connected in series with each other, and alternately conduction at an output frequency higher than that of the rectifying device. On/off the first and second switching devices for commutating the output of the rectifying device, the first capacitor connected in parallel to the first switching device, the output of the rectifying device is turned on at the second switching device through the second switching device During a period, the first capacitor is charged to perform a smooth operation on the output of the rectifying device. When the first switching device is turned on, the charge is released through the first switching device, and the node inserted between the first and second switching devices and Between the first capacitor, the inductor that can pass the charging current of the first capacitor, the second capacitor that resonates with the inductor according to the on/off operation of the first and second switching devices, and the inductor released according to the first capacitor , and the discharge current value flowing in the first switching device controls the conduction period of the first switching device to control the control unit of the resonance voltage value generated by the inductor and the second capacitor and the resonance generated by the inductor and the second capacitor Based on the output circuit to obtain high-frequency output.

According to a sixteenth aspect of the present invention, there is provided a lighting device for a discharge lamp, which includes a rectifying device connected to an AC power supply, connected in series between a pair of output terminals of the rectifying device, and having an output higher than that of the rectifying device. A series circuit of first and second switching devices with frequency on/off, a first capacitor with a large capacity, and an inductor, the series circuit is connected in parallel to the first switching device, has a small capacity and is set according to the first and The on/off operation of the second switching device forms a resonant second capacitor together with the inductor, has a current detection means for detecting a current flowing in the first switching device, and controls the first switching device based on a detection signal of the current detection means. A control unit for the conduction period of the switching device, and an output circuit for obtaining high-frequency output on the basis of resonance between the inductor and the second capacitor.

In the present invention, the first capacitor also smoothes the output frequency of the rectifying means. In addition, the second capacitor is arranged to form a resonant circuit together with the inductor. In this case, similarly to the nineteenth aspect, the second capacitor may be provided at any position as long as a resonance circuit can be formed.

According to the seventeenth aspect of the present invention, in the discharge lamp lighting device of the fifteenth or sixteenth aspect, the control unit controls the conduction period of the first switching device so that the first capacitor is discharged and the first switching device The peak value of the discharge current flowing inside becomes a predetermined value.

According to the eighteenth aspect of the present invention, in the discharge lamp lighting device of the fifteenth or sixteenth aspect, the control unit controls the conduction period of the first switching device so that the first capacitor is discharged through the inductor and the first switching device. The integrated value of the discharge current becomes a predetermined value.

In the present invention, the discharge current value of the first capacitor rises according to the slope determined by the impedance of the first capacitor, the inductor and the load. Therefore, by controlling the integrated value of the discharge current to a predetermined value, the current value in the first switching device during the off period can be controlled. In the present invention, for example, a saturation current transformer can be used as means for controlling the integral value to a predetermined value. This control may be performed by keeping the first switching device in a conductive state until the saturated current transformer is saturated. However, such means may also be constituted by current detection means and integrating means for integrating the output of the current detection means. In other words, it is possible to detect the time period during which the discharge current flows through the first switching device.

According to a nineteenth aspect of the present invention, in the discharge lamp lighting device of the fifteenth aspect, the control unit controls the conduction period of the first switching device so that the initial value of the resonance current flowing through the second switching device is a predetermined value. value.

According to the twentieth aspect of the present invention, in the discharge lamp lighting device according to one of the seventeenth to nineteenth aspects, the control device determines that the first switching device is turned on according to changes in the voltage values on the first and second switching devices. The predetermined value of the current value of the cycle.

According to a twenty-first aspect of the present invention, in the discharge lamp lighting device of one of the fifteenth to nineteenth aspects, the control unit turns off the second switching device after a current flows through it for a predetermined period of time.

According to a twenty-second aspect of the present invention, in the discharge lamp lighting device of any one of the fifteenth to nineteenth aspects, the control unit causes the second switching device to use the The second switching device turns on for a predetermined time.

According to a twenty-third aspect of the present invention, in the discharge lamp lighting device of any one of the fifteenth to nineteenth aspects, the control unit causes the second switch to device cut-off.

In the twenty-first to twenty-third aspects of the present invention, "a predetermined period of time" can be detected by detecting an integrated value of time or current. In addition, the predetermined time may be changed according to the AC voltage, the output voltage of the rectifier, the output voltage of the output circuit, or the like.

According to a twenty-fourth aspect of the present invention, in the discharge lamp lighting device of one of the fifteenth to nineteenth aspects, the control unit controls the conduction period of the second switching device according to a voltage corresponding to both ends of the first capacitor.

In this case, "according to the voltage across the first capacitor" means that the control can be performed not only directly but also indirectly according to the voltage across the first capacitor, such as according to the first and second capacitors voltage across.

According to a twenty-fifth aspect of the present invention, in the discharge lamp lighting device of one of the fifteenth to nineteenth aspects, the control unit controls the conduction period of the second switching device according to the AC voltage value.

According to a twenty-sixth aspect of the present invention, in the discharge lamp lighting device of one of the fifteenth to nineteenth aspects, the control unit controls the conduction period of the second switching device based on the output of the output circuit.

In the present invention, "the output of the output circuit" means output power, voltage or current. In addition, if a discharge lamp is connected as a load, the power of the discharge lamp, lamp voltage or lamp current can be used.

According to a twenty-seventh aspect of the present invention, the discharge lamp lighting device according to any one of the fifteenth to twenty-sixth aspects further includes a discharge lamp as a load.

According to a twenty-eighth aspect of the present invention, the discharge lamp lighting device of the twenty-seventh aspect is provided as a discharge lamp lighting device, wherein the discharge lamp is mounted on a lighting fixture as a load.

According to a twenty-ninth aspect of the present invention, there is provided a lighting device for a discharge lamp, which includes first and second switching elements connected in series with the output side of the rectifying device, a smoothing capacitor device with a large capacity and a load A circuit of connected inductive means connected in series with one of the first and second switching elements, and resonant capacitive means having a capacity smaller than the smoothing capacitive means, forming a resonant system together with the inductive means.

In the discharge lamp lighting device according to the first or second aspect, the unsmoothed DC voltage of the rectifying means is smoothed by the first capacitor. In addition, the voltage of the first capacitor is set lower than the unsmoothed voltage rectified by the switching device to the rectifying means during the switching period by the effect of the resonant voltage generated by the resonant circuit formed by the second capacitor and the inductor. With this operation, the input current can be ensured even during the period when the voltage peak of the AC mains (rectified unsmoothed DC voltage) is low, thereby improving the input power factor, reducing input current distortion, and reducing input current distortion. harmonic.

In addition, in the discharge lamp lighting apparatus according to the third aspect, the first and second switching devices are turned on/off at a substantially constant frequency, and the conduction cycle rate of these switching devices can be changed. By changing the conduction period, the resonance amplitude can be changed and thus the output voltage can be changed. Also, since the switching frequency is substantially constant, an increase in switching loss can be suppressed compared to a device in which the switching frequency is increased.

In addition, in the discharge lamp lighting device according to the fourth aspect, the conduction cycle rates of the first and second switching devices can be changed. When the peak value of the voltage output in each half cycle of the AC power supply is relatively large, the conduction period of the other switching device is shortened, and vice versa. As in the fourth aspect, changing the conduction rate can adjust the output voltage. Moreover, according to the peak value of the voltage output of each half cycle of the AC power supply, a sufficiently smooth output voltage can be obtained by changing the conduction period of a switching device.

In the discharge lamp lighting apparatuses according to the fifth and sixth aspects, changing the switching frequency can change the absolute conduction period of the other switching device, and the output can be changed as described above.

In the discharge lamp lighting device according to the seventh aspect, since the second capacitor is connected in parallel to the other switching device and the inductor, the above object can be achieved with a simple structure.

In the discharge lamp lighting device according to the eighth aspect, since the second capacitor is connected between the output terminals of the rectifying means, as in the device according to the seventh aspect, the above object can be achieved with a simple structure.

In the discharge lamp lighting apparatus according to the ninth aspect, since the second capacitor is connected between the rectifying means and the pair of switching devices, it is possible to achieve the above objects with a simple structure similarly to the apparatus according to the eighth aspect.

In the discharge lamp lighting device according to the tenth aspect, the output circuit includes an impedance circuit whose impedance decreases as frequency increases. Therefore, even if the oscillation frequency is increased, the impedance of the line for reducing distortion can be kept small, and a sufficient resonance current can be obtained.

In the discharge lamp lighting apparatus according to the eleventh aspect, since the drive transformer stops oscillation of the first and second switching devices when the load is removed, an increase in voltage applied to the first and second switching devices can be prevented.

In the discharge lamp lighting device as the discharge lamp lighting device according to the twelfth aspect, since the discharge lamp is used as a load, it is possible to reduce output fluctuations, improve luminous efficiency, and reduce light fluctuations.

In the discharge lamp lighting device serving as the discharge lamp lighting device according to the thirteenth aspect, since the conduction period of the other switching device during a predetermined start-up operation of the discharge lamp is set smaller than the conduction period during lamp lighting , so start the discharge lamp after sufficient preheating of the filament. Therefore, shortening of the service life of the discharge lamp can be prevented.

In the discharge lamp lighting device for use as a lighting device according to the fourteenth aspect, since the discharge lamp lighting device is mounted on the lamp, luminous efficiency is improved, fluctuations in lamp current are reduced, and light fluctuations are reduced.

In the discharge lamp lighting devices according to fifteenth and sixteenth, the output of the rectifying means charges the first capacitor and maintains the smoothed DC voltage having a value smaller than the peak value of the unsmoothed DC voltage. In addition, a resonance circuit formed by the second capacitor and the inductor generates a resonance voltage according to switching of the first and second switching devices. The resonant voltage forms a period during which the load voltage seen from the rectifier device is substantially lower than the unsmoothed direct voltage over the entire period of the unsmoothed direct voltage. For this mode of operation, even when the peak value of the unsmoothed DC voltage is low, the input current can be guaranteed to be obtained from the AC power supply (a charging current flows in the first capacitor), thereby improving the input power factor and reducing the input voltage. Current distortion, reducing harmonics in the input current. In addition, the resonance voltage is controlled by controlling the conduction period of the first switching device according to the value of the discharge current discharged from the first capacitor and flowing in the first switching device. For example, the conduction period of the first switching device which determines the amplitude of the resonance voltage is controlled so that the peak value of the current flowing in the first switching device becomes a predetermined value. For this mode of operation, as described with reference to Figs. 23A and 23B, the resonance voltage value can be controlled to be constant. Therefore, the voltage value applied to the pair of switching devices can be controlled to prevent breakdown of the switching devices, thereby enabling the use of switching devices with a low breakdown voltage.

Moreover, by changing the predetermined value that determines the conduction period, the output voltage value can be changed arbitrarily, so that the changed voltage value is constant.

In the discharge lamp lighting device according to the seventeenth aspect, since the conduction period of the first switching device can be controlled so that the peak value of the current flowing in the first switching device becomes a predetermined value, it can be obtained as in the fifteenth and tenth The six-sided discharge lamp lighting device has the same effect.

In the discharge lamp lighting device according to the eighteenth aspect, the conduction period of the first switching device is controlled so that the integrated value of the discharge current becomes a predetermined value. With this mode of operation, basically the same effects as those of the discharge lamp lighting device of the seventeenth aspect can be obtained.

In the discharge lamp lighting device according to the nineteenth aspect, the conduction period of the first switching device is controlled such that the initial value of the resonance current flowing in the second switching device becomes a predetermined value. Therefore, also in this case, the current which determines the resonance voltage flowing into the resonance circuit can be made constant to control the value of the resonance voltage at a constant value. In the present invention, the control is based on the value of the discharge current previously flowing through the first switching device, and therefore, the control has a delay. However, no practical problem arises if this delay is shortened to, for example, one high-frequency wave period.

In the discharge lamp lighting apparatus according to the twentieth aspect, the value of the current flowing through the first switching device which determines the conduction period of the first switching device is changed according to the voltage values across the first and second switching devices. For example, changing the detected voltage or a reference signal to which the detected current is compared. For this mode of operation, the voltage across the first and second switching device can be kept constant.

In the discharge lamp lighting device according to the twenty-first aspect, since the second switching device is turned off after a predetermined period of time after a current flows therein, a charging current can be ensured to flow from the rectifying means to the first capacitor. Therefore, input current distortion can be reduced.

In the discharge lamp lighting device according to the twenty-second aspect, since the second switching device is turned off for a predetermined time after the peak portion of the resonance current flows, a charging current is reliably supplied from the rectifying means after the peak portion flows. flows into the first capacitor for a predetermined period of time. Therefore, the same effects as those of the discharge lamp lighting device of the twenty-first aspect can be obtained.

In the discharge lamp lighting device according to the twenty-third aspect, since the input/output current flows into the rectifying device for a predetermined period of time, the same effects as those of the discharge lamp lighting devices of the twenty-first and twenty-second aspects can be obtained .

In the discharge lamp lighting device according to the twenty-fourth aspect, in addition to the operations in the fifteenth to nineteenth aspects, the conduction of the second switching device is controlled according to the voltage value corresponding to the voltage on the first capacitor. The pass cycle is used to control the charging amount of the first capacitor. Therefore, the voltage across the first capacitor can be made constant. With this mode of operation, even if the power supply voltage varies, the voltage on the first capacitor can be kept constant, and the voltage applied to the load can also be kept constant.

In the discharge lamp lighting device according to the twenty-fifth aspect, since the conduction period of the second switching device is controlled according to the AC power supply voltage, the voltage on the first capacitor can be made constant by controlling the charge amount of the first capacitor. With this mode of operation, even if the power supply voltage varies, the voltage on the first capacitor can be kept constant, and the voltage applied to the load can also be kept constant.

In the discharge lamp lighting device according to the twenty-sixth aspect, the charge amount of the first capacitor is controlled by controlling the conduction period of the second switching device according to the output of the output circuit, thereby making the voltage on the first capacitor constant. With this mode of operation, even if the load varies, the voltage on the first capacitor can be kept constant, and the voltage applied to the load can also be kept constant.

In the discharge lamp lighting device used as the discharge lamp lighting device according to the twenty-seventh aspect, the discharge lamp is used as the load. Therefore, in addition to the effect of the discharge lamp lighting device, the output fluctuation is reduced, the luminous effect is improved, and the light fluctuation is reduced.

In the discharge lamp lighting device used as a lighting device according to the twenty-eighth aspect, since the discharge lamp device is arranged in the device body, luminous efficiency is improved and light fluctuation is reduced.

In the discharge lamp lighting device according to the twenty-ninth aspect, the high-frequency voltage generated by the resonant system constituted by the resonant capacitor means and the inductance means becomes the AC voltage rectified by the rectifying means. For this mode of operation, the rectified output voltage is equal to the input voltage to ensure that there is an input voltage even in the cycle of low AC voltage, thereby reducing the distortion of the input current and reducing the resonance component.

Additional objects and advantages of the invention will be set forth in the description which follows, and in part will become apparent from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of intermediary and comprehensive methods, particularly as set forth in the appended claims.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate the preferred embodiment of the invention and, together with the general description given above and the detailed description of the preferred embodiment given below, serve to explain the Principle of the invention.

Fig. 1 is the circuit diagram of the first embodiment of the present invention;

2 is a perspective view of the present invention applied to a lighting device;

3A to 3C are waveform timing diagrams of the voltage of the current on each part illustrating the effect of the embodiment shown in FIG. 1;

Fig. 4 is the circuit diagram of the 2nd embodiment of the present invention;

FIG. 5 is a graph of the conduction period of the switching device in FIG. 4;

6A to 6E are equivalent circuit diagrams illustrating the operation of the embodiment shown in FIG. 4;

Fig. 7 is under the situation that the conduction period of the second switch device is set shorter, the voltage and the electric current of the voltage and electric current of the effect of the embodiment shown in Fig. 4 are illustrated on each component;

Fig. 8 is under the situation that the conduction period of the second switching device is set longer, the voltage and the electric current of the voltage and electric current of the effect of the embodiment shown in Fig. 4 are illustrated on each component;

Fig. 9 is under the situation that the conduction period of the second switching device is set longer, the voltage and the electric current waveform timing chart on each component of the effect of the embodiment shown in Fig. 4;

Fig. 10 is the circuit diagram of the 3rd embodiment of the present invention;

Fig. 11 is the circuit diagram of the 4th embodiment of the present invention;

Fig. 12 is a graph explaining the effect of Fig. 11 embodiment;

Fig. 13 is the circuit diagram of the 5th embodiment of the present invention;

Fig. 14 is a sequence diagram explaining the sixth embodiment of the present invention;

Fig. 15 is a circuit diagram of the seventh embodiment of the present invention;

Fig. 16 is the circuit diagram of the 8th embodiment of the present invention;

Fig. 17 is a circuit diagram of the ninth embodiment of the present invention;

Fig. 18 is a circuit diagram of the tenth embodiment of the present invention;

Fig. 19 is a circuit diagram of the eleventh embodiment of the present invention;

Fig. 20 is a circuit diagram of the twelfth embodiment of the present invention;

21A to 21E are hierarchical circuit diagrams illustrating the operation of the embodiment shown in FIG. 20;

22A and 22B are timing diagrams illustrating the embodiment shown in FIG. 20;

23A and 23B are timing diagrams illustrating the embodiment shown in FIG. 20;

24A to 24C are timing diagrams illustrating the embodiment shown in FIG. 20;

25A to 25C are timing diagrams illustrating the embodiment shown in FIG. 25;

Fig. 26 is a circuit diagram of the thirteenth embodiment of the present invention;

Fig. 27 is a circuit diagram of the 14th embodiment of the present invention;

Fig. 28 is a perspective view schematically illustrating the application of the present invention to a lighting device;

Fig. 29 is a circuit diagram of the fifteenth embodiment of the present invention;

30A to 30C are timing charts showing waveforms of the voltage on the second capacitor and the current in each switching device in the case where the conduction period of the second switching device in FIG. 29 is short;

31A to 31C are timing charts showing waveforms of the voltage on the second capacitor and the current in each switching device when the conduction period of the second switching device in FIG. 29 is large;

FIG. 32 is a timing diagram showing the voltage between the output terminals of the rectifier in FIG. 29;

FIG. 33 is a timing diagram showing load current in FIG. 29;

Fig. 34 is a circuit diagram of the sixteenth embodiment of the present invention;

Fig. 35 is a circuit diagram of the seventeenth embodiment of the present invention;

36 is a timing chart of current waveforms in the second switching device in a case where the voltage between the output terminals of the rectifying means becomes higher;

FIG. 37 is a timing chart of current waveforms in the second switching device when the voltage between the output terminals of the rectifying means becomes lower;

38A to 38E are graphs showing test results, in particular, graphs showing changes in each output terminal as the power supply voltage varies;

Fig. 39 is a circuit diagram of the eighteenth embodiment of the present invention;

Fig. 40 is a circuit diagram of the nineteenth embodiment of the present invention;

Fig. 41 is a circuit diagram of the twentieth embodiment of the present invention;

Fig. 42 is a circuit diagram of the twenty-first embodiment of the present invention;

Fig. 43 is a circuit diagram of the 22nd embodiment of the present invention;

Fig. 44 is a circuit diagram of the 23rd embodiment of the present invention;

FIG. 45 is a timing diagram of current waveforms in the second switching device in FIG. 44;

Fig. 46 is a circuit diagram of the twenty-fourth embodiment of the present invention;

47A to 47C are timing diagrams of current waveforms in the first and second switching devices in FIG. 46;

Fig. 48 is a perspective view illustrating application of the improved discharge lamp lighting device of the present invention to a lighting device;

Fig. 49 is a circuit diagram of a main part structure of a discharge lamp lighting device applied to a DC load circuit;

Fig. 50 is a circuit diagram of prior art 1;

FIG. 51 is a circuit diagram of prior art 2. FIG.

In the first embodiment, the discharge lamp lighting device of the present invention is applied to the discharge lamp lighting device, and the first embodiment and the lighting device will be described below with reference to FIGS. 1 to 3 .

As shown in FIG. 2 , the lamp holder 12 is fixed to both ends of the lamp 11 , and the lower surface of the lamp 11 forms a reflective surface. A load, that is, a fluorescent lamp FL as a discharge lamp is installed between the sockets 12 . A discharge lamp lighting circuit 16 as shown in FIG. 1 is provided in the lamp 11 .

A filter circuit 21 composed of a coil L1 and a capacitor C1 is connected to the commercial AC power supply E of the discharge lamp lighting circuit 16 . To the filter circuit 21, a full-wave rectifier 22 as a high-speed switching rectification means such as a diode bridge is connected. The first and second switching elements Q1 and Q2 constitute a half-bridge type inverter circuit 23 and are connected between output terminals of the full-wave rectifier 22 in series. Freewheeling diodes D1 and D2 are connected in parallel to the first and second switching elements Q1 and Q2.

A series circuit of a primary winding _Tr1a of a magnetic leakage isolation transformer Tr1 as an inductance device and a smoothing capacitor C2 with a _large capacity as a smoothing capacitor device is connected in parallel with the first switching element Q1 to form a circuit 24 . Note that the smoothing capacitor C2 smoothes the power frequency of the industrial AC power supply E.

The filaments FL1 and FL2 of the fluorescent lamp FL are connected to the secondary winding _Tr1b of the isolation transformer _Tr1 . A capacitor C3 for preheating the filament is connected between the filaments FL1 and FL2.

A resonance capacitor C4 having a smaller capacity serving as resonance capacitance means is connected to the second switching element Q2 through the primary winding _Tr1a of the isolation transformer _Tr1 . Note that the resonant capacitor C4, which is much smaller in capacity than the smoothing capacitor C2, is used together with the inductance of the isolation transformer _Tr1 to generate an oscillating waveform whose frequency is the switching frequency of the first and second switching elements Q1 and Q2.

The operation of the embodiment of Fig. 1 will be described below.

First, the noise in the voltage of the commercial AC power supply E is removed by the filter circuit 21 . This voltage is then full-wave rectified in a full-wave rectifier 22 . The first and second switching elements Q1 and Q2 are switched alternately at a high frequency higher than the frequency of the AC power supply to induce a high-frequency AC voltage on the secondary winding _Tr1b of the isolation transformer _Tr1 , thereby lighting the fluorescent lamp FL at a high frequency . In addition, the resonant capacitor C4 and the primary winding of the isolation transformer _Tr1 resonate to provide current with improved power factor when the AC voltage rectified by the full-wave rectifier 22 is at a low level, thereby reducing distortion.

More specifically, when the first switching element Q1 is turned on, current flows through _{a closed circuit formed by the smoothing capacitor C2, the first switching element Q1, the primary winding Tr1a of} the isolation transformer Tr1, and the smoothing capacitor C2. Accordingly, the primary winding _Tr1a of the isolation transformer Tr1 _is charged.

Next, when the first switching element Q1 is turned off, the charge on the primary winding _{Tr1a of} the isolation transformer _Tr1 is released through the closed circuit formed by the resonant capacitor C4, the diode D2 and the primary winding _Tr1a of the isolation transformer Tr1. At this time, _the voltage of the resonance capacitor C4 rises due to the resonance action of the resonance capacitor C4 and the primary winding _Tr1a of the isolation transformer Tr1.

When the second switching element Q2 is turned on, current flows in a closed circuit formed by the resonance capacitor C4, the primary winding _Tr1a of the isolation transformer _Tr1 , the second switching element Q2, and the resonance capacitor C4. Accordingly, the primary winding _Tr1a of the isolation transformer Tr1 _is charged. At this time, the voltage on the resonant capacitor C4 drops.

When the voltage on the resonant capacitor C4 drops, and the voltages on the resonant capacitor C4 and the smoothing capacitor C2 become equal to the input voltage, current flows through the full wave rectifier 22 . Therefore, the power factor of the current flowing in the closed circuit formed by the full-wave rectifier 22, the smoothing capacitor C2, the primary winding _Tr1a of the isolation transformer _Tr1 , the second switching element Q2, and the full-wave rectifier 22 is improved, thereby reducing distortion.

When _the second switching element Q2 is turned off, the energy stored in the primary winding _Tr1a of the isolation transformer _Tr1 is discharged through a closed circuit formed by the diode D1, the smoothing capacitor C2 and the primary winding _Tr1a of the isolation transformer Tr1. Therefore, energy is charged into the smoothing capacitor C2.

When implemented with the embodiment shown in Fig. 1, currents and voltages as shown in Figs. 3A to 3B can be obtained. FIG. 3A shows the input current Iin; FIG. 3B shows the output voltage V22 of the full-wave rectifier 22; FIG. 3C shows the voltage of the fluorescent lamp FL. That is, output ripple can be reduced.

In addition, by isolating the primary winding _Tr1a of the transformer Tr1 and the second switching element Q2, _the start-up current flowing to the smoothing capacitor C2 at the time of power-on operation can be reduced.

Also, even if the connections of the smoothing capacitor C2 and the resonant capacitor C4 are exchanged with each other, the effects as described above can be obtained.

Another embodiment of the present invention will be described below with reference to the accompanying drawings.

Referring now to FIGS. 4 to 9, a second embodiment of the present invention will be described. Referring to FIG. 4 , for example, the filter circuit composed of a choke coil 2 and a capacitor 3 is connected to an industrial AC power supply 1 . A full-wave rectifier as rectifier 4 constituted by, for example, a diode bridge or the like is connected to the filter circuit. The rectifying device 4 (diode bridge) is constituted, for example, by high-speed switching diodes. The first and second switching devices 5 and 6 are connected in series between a pair of output terminals of the rectifying device 4 . In this embodiment, these switching devices 5 and 6 are constituted by field effect transistors, using parasitic diodes as diodes for passing reverse current.

A series circuit of a primary winding 7-1 of a magnetic leakage type isolation transformer serving as an inductor 7 and a smoothing capacitor having a large capacity serving as a first capacitor 8 is connected to a switching device, such as in this embodiment. on the first switching device 5 . Note that the first capacitor 8 has a smoothing effect on the power frequency of the commercial AC power supply 1 .

In this embodiment, an output circuit is formed on both ends of the inductor 7 . That is, the secondary winding 7-2 of the inductor 7 is used as an output circuit. A discharge lamp, for example a fluorescent lamp 9, is connected to the second winding 7-2 as a load. A capacitor 10 for preheating the filaments is connected between the filaments of the fluorescent lamp 9 . In this embodiment, the leakage inductance of the inductor 7 is also used as a current limiting inductance for the fluorescent lamp 9 .

In this embodiment, a resonant capacitor serving as the second capacitor 11 with a smaller capacity is connected in parallel to another switching device, ie, the second switching device 6, through the primary group 7-1 of the inductor 7. Note: the capacity of the second capacitor 11 is much smaller than that of the first capacitor 8, and is used to generate an oscillation waveform together with the inductance of the inductor 7, whose frequency is the switching frequency of the first and second switching devices 5 and 6.

Also, in this embodiment, the switch control unit 12 is configured to control the on/off operations of the switching devices 5 and 6 . The switch control unit 12 turns on/off the switching devices 5 and 6 at a substantially constant frequency. In addition, the switch control unit 12 can change the conduction period of the switching device 6 according to the peak value of the output voltage of the AC power supply 1 (the output voltage of the rectifying device 4) as shown in FIG. 5. More specifically, when the AC power supply 1 When the peak value of the output voltage (the output voltage of the rectifying device 4) was larger, the switch control unit 12 shortened the conduction period, and vice versa.Therefore, the conduction period of the first switch device 5 and the second switch device 6 changed oppositely. And , in this embodiment, the conduction period of the second switching device 6 can also be changed according to an external signal. More specifically, the switch control device 12 is composed of a detection circuit 12-1 for detecting an input voltage and a detection circuit for detecting The voltage that 12-1 detects changes the oscillating circuit 12-2 formation of conduction cycle.For oscillating circuit 12-2, can make such as integrated circuit as PWM controller (as: the TL494 that Texas Instruments produces) The switch control unit 12 also includes an external control signal input section 12-3.

Effects of the present invention are described below. The overall operation of the device is now briefly described. First, the noise of the industrial AC power supply 1 voltage is removed by a filter circuit. The voltage is then full-wave rectified in the rectification device 4 . Simultaneously, the first and second switching devices 5 and 6 switch alternately at a frequency higher than the power supply frequency, and a high-frequency AC voltage is induced on the secondary winding 7-2 of the inductor 7, thereby lighting the fluorescent lamp 9 at high frequency. In addition, the second capacitor 11 and the inductor 7 generate a resonance voltage. The resonance voltage has the effect of supplying a current with a changed power factor even when the peak value of the voltage rectified by the rectifying device 4 is small, thereby reducing distortion.

The operation of the circuit will be described in detail below with reference to FIGS. 6A to 9 . Note: Figures 6A to 6E only schematically show the main parts needed to explain the operation of the circuit. The same reference numerals in FIGS. 6A to 6E denote the same components as those in FIG. 4 . Figures 7 to 9 show the voltage and current waveforms of the various components. Referring to FIGS. 7 to 9, the reference symbol V denotes voltage, I denotes current, and each suffix denotes a corresponding component in FIG. 4 (however, “VGS5” in FIGS. , "VGS6" represents the gate-source voltage of the second switching device 6).

First, a period in which the AC power peak (unsmoothed DC voltage) is large will be described with reference to FIGS. 6A to 6E and FIG. 7 . In a cycle with a larger peak value, the switch control unit 12 controls the second switch device according to the detected voltage, and sets the conduction cycle to be shorter.

In the period (a) (“(a)” in FIG. 6A and FIG. 7 ), since a closed loop of the first capacitor 8, the first switching device 5 and the inductor 7 is formed, the charge stored in the first capacitor 8 By this closed circuit release, currents I5 and I8 flow as shown in FIG. 7 .

In period (b) (“(b)” in FIG. 6B and FIG. 7 ), the first switching device 5 is turned off, and the parasitic diode of the second switching device 6 is turned on. Therefore, the inductor 7 and the second capacitor 11 generate series resonance, and the resonance currents I6 and I11 flow as shown in FIG. 7 . For this operation, resonance voltages V11 and V7 as shown in FIG. 7 appear on the second capacitor 11 and the inductor 7 . In addition, a resonant voltage V4 appears across the rectifier 4 , which is equal to the sum of the voltages across the second capacitor 11 and the first capacitor 8 .

In period (c) (“(c)” in FIG. 6c and FIG. 7 ), the second switching device 6 is turned on, and the polarity of the resonance current is reversed. Therefore, the resonance currents I6 and I11 flow in the opposite direction to that in FIG. 6B . Since the resistance component of the resonance circuit is small, the resonance voltages V7 and V11 at periods (b) and (c) become higher than the rectified wave ripple voltage. That is, the resonance voltage rises.

During period (d) (“(d)” in FIG. 6D and FIG. 7 ), the resonance voltage drops, and the voltages on the second capacitor 11 and the first capacitor 8 also tend to drop. Accordingly, the currents I4, I8 and I6 flow from the rectifying device 4 through the first capacitor 8, the inductor 7 and the second switching device 6 as shown in FIG.

In period (e) (“(e)” in FIG. 6E and FIG. 7), the second switching device 6 is turned off, and the parasitic diode of the first switching device 5 is turned on, so, as shown in FIG. Currents I5 and I8 flow in the first switching device 5 and the first capacitor 8 due to the energy in the device 7 . Thereafter, it returns to the state of period (a).

The period when the peak value of the AC power supply voltage is small will be described below with reference to FIG. 8 . During this period, the switch control unit 12 detects the voltage and controls to make the conduction period of the second switching device 6 longer. In this case, the operation of the circuit is basically the same as that shown in FIGS. 6A to 6E. Figure 8 shows the voltage and current waveforms across the components. It should be noted that in the case shown in FIG. 8 , the amplitudes and peak values of the resonant voltages V4 and V11 are larger than those shown in FIG. 7 . This is because the conduction period is long, and the periods (b) and (c) are relatively extended. Also because the charging voltage on the second capacitor 11 becomes lower according to the peak value in the period in which the peak value of the unsmoothed DC voltage is small, the current flowing into the second capacitor 11 at period (b), that is, the initial resonance current increases. Therefore, as the peak of the unsmoothed DC voltage becomes lower, the voltage can rise higher, and the valley of the unsmoothed DC voltage can also be raised. As described above, in the circuit shown in FIG. 4 , the conduction periods of the switching devices 5 and 6 are controlled according to the relationship shown in FIG. 5 . For this reason, the conduction period of the first switching device 5 is shorter in periods with smaller peak values. With this arrangement, the current flowing into the switching device 5 is turned off at the stage where the current value is small. This makes the initial resonance current value at the period (b) smaller. Therefore, as described above, even if the resonance voltage rises due to the voltage charged on the second capacitor 11, the valley voltage value does not increase excessively due to the sharp boost operation.

When experimenting with the embodiment shown in FIG. 4, the waveform of the input current Iin of the AC power supply 1 is shown in FIG. 3A. As mentioned above, this means that during period (d) the current of the rectifying device 4 flows throughout the cycle of the unsmoothed DC voltage of the rectifying device 4 . Therefore, it should be understood that this current improves the input power factor and helps reduce input current distortion. In addition, FIG. 3B shows the waveform of the voltage V4 between the output terminals of the rectifying device 4 , and FIG. 3C shows the waveform of the current in the fluorescent lamp 9 . That is, it should be understood that output ripple can be reduced.

If the conduction period of the second switching device 6 is controlled by an external signal, the output voltage can be changed. More specifically, if the conduction period of the second switching device 6 is set longer, the output voltage becomes higher, and vice versa. Therefore, like this embodiment, when a discharge lamp is used as a load, the lamp can be dimmed/lit arbitrarily. Figure 9 shows the voltage and current waveforms of each component when the conduction period is further shortened.

By connecting the inductor 7 in series with the first capacitor 8 and turning on/off the second switching device 6 at a high frequency, the current flowing into the first capacitor 8 at the time of power-on operation can be reduced.

Even if the connection positions of the first and second capacitors 8 and 11 are changed to exchange them with each other, the effects as described above can be obtained. In this case, also reverse the connection of the switching device that controls the conduction period.

Fig. 10 is a circuit diagram of a third embodiment of the present invention. In this embodiment, an isolation transformer having no additional leakage inductance is used as the inductor 7', and the inductor 15 is connected in series with the primary winding 7'-1 of the isolation transformer. The same reference numerals in FIG. 10 denote the same components in FIG. 4, and therefore, their descriptions are omitted. Note that switching devices 5 and 6 are shown in simplified form. In the present embodiment, the inductor 15 is used as a current-limiting impedance of the fluorescent lamp 9 .

It is easy to understand that for the arrangement shown in FIG. 10 , the same effect as the embodiment of FIG. 4 can be obtained. Thus, descriptions of these effects are omitted.

Fig. 11 is a circuit diagram of a fourth embodiment of the present invention. In this embodiment, an impedance circuit composed of a coil 16 and a capacitor 17 is connected in parallel with the primary winding 7-1 of the isolation transformer as the inductor 7 in the embodiment of FIG. 4 . Note that, as shown in Fig. 12, the characteristic impedance of this impedance circuit is minimum at frequency f1.

In this embodiment, the oscillation frequency of the inverter circuit rises when dimming/lighting the fluorescent lamp 9 (in the left range of "f1" in FIG. 12 ) compared to the oscillation frequency when the fluorescent lamp 9 is fully lit. , reducing the output. When the oscillation frequency increases, the conduction period of the second switching device 6 is shortened. Therefore, as can be understood from the description with reference to FIGS. 8 and 9 , the output is reduced.

In this case, since the characteristic impedance of the impedance circuit will decrease as the frequency increases, the impedance circuit changes from being open to being connected in parallel with the inductor 7 . If the constant of the impedance circuit is set so that when the impedance circuit is connected in parallel with the inductor 7, the resonant frequency of the resonance circuit increases, then such a cycle (see "(b)" in Fig. 7 and Fig. 8 ) can be guaranteed, in which During the cycle, after resonance, current flows from the rectifier 4 . Therefore, the current stop period can be eliminated, and the distortion can be reduced throughout the entire period from the fully lit period to the dimmed/lit period.

Fig. 13 is a circuit diagram of a fifth embodiment of the present invention. In this embodiment, the first switching device in the embodiment shown in FIG. 4 is composed of bipolar transistors 5'-1 and diodes 5'-2 connected in parallel. As the first switching device 5', they are connected in parallel The connected bipolar transistor 6'-1 and diode 6'-2 constitute a second switching device as the second switching device 6'. The primary winding 8 of the driving transformer 18 is connected as the inductor 7 between the fluorescent lamp 9 and the secondary winding 7-2 of the isolation transformer. The secondary winding 18-2 of the drive transformer 18 is connected between the base and the emitter of the bipolar transistor 5'-1 of the first switching device 5'. The secondary winding 18-3 of the drive transformer 18 is connected between the base and emitter of the bipolar transistor 6'-1 of the second switching device 6'. For this arrangement, base current is supplied to the respective switching devices 5' and 6'.

In this embodiment, when the fluorescent lamp 9 is removed to open the circuit, no current flows in the primary winding 18-1 of the driving transformer 18, so there is no output on the secondary windings 18-2 and 18-3 of the driving transformer 18. Therefore, no base current flows in the switching devices 5' and 6', and the oscillation of the circuit as an inverter circuit stops.

Since the oscillation of the inverter circuit stops when the fluorescent lamp 9 is removed, the voltages applied to the first and second switching elements 5' and 6' can be reduced compared with the case of switching even when there is no load. In the no-load state, the resistance component of the impedance circuit is substantially zero. In this state, the kurtosis of the resonant circuit is large, and the resonant voltage is also high. Therefore, if the oscillation continues for a long period of time in the no-load state, a large resonance voltage will be applied to the switching devices 5' and 6', resulting in damage or breakdown of the switching devices 5' and 6'.

If the first and second switching devices 5' and 6' are formed by field effect transistors, the outputs of the respective secondary windings are provided on corresponding gate-source paths. Therefore, also in this case, the same effect as described above can be obtained.

Fig. 14 is a timing chart of the sixth embodiment of the present invention. In this embodiment, the circuit arrangement of the embodiment shown in FIG. 4 is used. When the voltage of the industrial AC power supply 1 (indicated by "(a)" in Figure 14 is low, the inverter oscillates at a predetermined frequency f0, at which frequency the input current becomes one indicated by Figure 14(b) The predetermined value.When the voltage of industrial AC power supply 1 was high, FM modulation was carried out to increase the frequency to the frequency indicated by the dotted line.For this mode of operation, the conduction period of the second switching device is set to be shorter than The conduction period at the frequency f0 reduces the output voltage of the inverter circuit, thereby setting the fluorescent lamp 9 in a dimmed state.

In this way, when the output voltage of the rectifying device 4 is low, the frequency is fixed, and the conditions are set in advance to eliminate the current stop period at this frequency, thereby providing current with improved power factor. For this mode of operation, high power factor can be maintained and distortion can be reduced.

The resonance effect between the inductance of the inductor 7 and the capacitance of the second capacitor 11 determines the waveform of the high-frequency ripple current superimposed on the AC voltage, which cannot be controlled by the first switching device 5 alone. That is, there must be a period within the conduction period of the second switching device 6 during which the voltages of the first capacitor 8 and the second capacitor 11 are lower than the input voltage of the rectifying device 4 . This operation can be done reliably.

It is also possible to apply the control shown in Fig. 14 to embodiments other than the Fig. 4 embodiment.

Fig. 15 is a circuit diagram of a seventh embodiment of the present invention. In this embodiment, similar to the embodiment shown in FIG. 13, the first and second switching devices in the embodiment shown in FIG. 4 are mainly constituted by bipolar transistors as the first and second switching devices 5' and 6'. A series circuit of a third capacitor 19 with a larger capacity and a coil 20 as an impedance element and a fourth capacitor 21 with a smaller capacity are connected in parallel to replace the first capacitor 8 .

The third capacitor 19 requires a large capacity to store energy for smooth operation. Therefore, an electrolytic capacitor is used as the third capacitor 19 . However, if a current with large ripples flows through this electrolytic capacitor, the service life of the capacitor will be shortened. Therefore, in this embodiment, the coil 20 serving as an impedance element is used to prevent high-frequency current from flowing into the capacitor 19 through the capacitor 21 .

Therefore, in this embodiment, the low frequency component is smoothed by the series circuit of the third capacitor 19 and the coil 20, and the high frequency ripple current is supplied to the fourth capacitor 21 to reduce the high frequency ripple current flowing into the third capacitor 19. .

Power is mainly supplied to the inverter circuit by the fourth capacitor 21 . When the voltage on the fourth capacitor 21 drops, the fourth capacitor 21 is charged from the third capacitor 19 .

Fig. 16 is a circuit diagram of an eighth embodiment of the present invention. In this embodiment, the second capacitor in the embodiment of FIG. 4 is improved. More specifically, a series circuit composed of the capacitors 22 and 23 and the switching element 24 as capacitor changing means constitutes the second capacitor.

When the fluorescent lamp 9 is preheated and started, the switching element 24 is turned on, and the capacitor 23 is connected in parallel to the capacitor 22 to increase the combined capacitance. For this operation, the resonant frequency is lowered during the preheat/start cycle to prevent overvoltage and suppress input current distortion.

Fig. 17 is a circuit diagram of a ninth embodiment of the present invention. In this embodiment, the switching element 24 in the embodiment shown in FIG. 16 is replaced by a diode 25 connected thereto and a field effect transistor 26 serving as a capacitor varying means.

In this case, the capacitor 23 cannot be charged when the field effect transistor 26 is turned off. When the field effect transistor 26 is turned on, the capacitor 23 can be charged. Note that capacitor 23 can always be discharged through diode 25. In this method, when only the capacitor 22 is used, the capacity decreases, and when a parallel circuit of the capacitors 22 and 23 is used, it tends to increase, thus changing the capacity.

The embodiment shown in FIG. 17 works in the same manner as the embodiment shown in FIG. 16 and can achieve the same effects.

Fig. 18 is a circuit diagram of a tenth embodiment of the present invention. In this embodiment, the resonant capacitor 22 and the capacitor 23 in the embodiment of FIG. 17 are connected in series.

In this case, when the field effect transistor 26 is turned off, the capacitor 23 cannot be charged. When the field effect transistor 26 is turned on, it can charge the capacitor 23 . Note that capacitor 23 can always be discharged through diode 25. In this manner, when only the capacitor 22 is used, the capacity is reduced, and when a parallel circuit of the resonance capacitor 22 and the capacitor 23 is used, the capacity is increased, so that the capacity can be changed substantially.

This embodiment works in the same manner as the embodiments shown in Fig. 16 and Fig. 18, and can obtain the same effects.

Fig. 19 is a circuit diagram of an eleventh embodiment of the present invention. This embodiment includes a short circuit detection circuit 27b for detecting a short circuit phenomenon based on the output of the voltage detection circuit 27a for detecting the voltage of the first capacitor 8 in the embodiment shown in FIG. The operation of 27b controls the oscillation of the first and second switching devices 5 and 6 .

When the voltage of the first capacitor 8 rises to a predetermined value or higher, the short-circuit detection circuit 27b determines that this is that the fluorescent lamp 9 is taken off, and the first and second switching devices 5 and 6 are stopped from oscillating by the drive circuit 28, thereby stopping Oscillation of the inverter circuit.

In this manner, overvoltage is prevented from being applied to the first and second switching devices 5 and 6 by stopping the oscillation of the inverter circuit when the fluorescent lamp 9 is removed.

The voltage detection circuit 27 a can also detect the lamp current in the fluorescent lamp 9 . When the lamp current reaches a predetermined value or higher, for example, the current in the primary winding 7-1 of the inductor 7 becomes a predetermined value or less, the voltage detection circuit 27a can determine that the fluorescent lamp 9 is turned off.

In addition, the short-circuit detection circuit 27 b may detect the lamp voltage of the fluorescent lamp 9 . When the lamp voltage reaches a predetermined value or higher, the short detection circuit 27b can determine that the fluorescent lamp 9 is removed.

Fig. 20 is a circuit diagram of a twelfth embodiment of the present invention. In this embodiment, the second capacitor 11' is connected between the output terminals of the rectifying device 4 in the embodiment of FIG. 4 .

Effects of the present embodiment will be described below with reference to FIGS. 21A to 21E. 21A to 21E correspond to FIGS. 6A to 6E and FIG. 7 . In period (a) ( FIG. 21A ), current flows from the first capacitor 8 to the switching device 5 ′ and the primary winding 7 - 1 of the inductor 7 .

In period (b) (FIG. 21B), the primary winding 7-1 of the inductor 7, the first capacitor 8, the second capacitor 11', the parasitic diode 6'-2, and the primary winding 7-1 of the inductor 7 form a closed circuit . During this period, the inductor 7 and the second inductor 11' generate series resonance. Since the capacity of the first capacitor 8 is set to be greatly larger than that of the second capacitor 11', in this case, the resonance condition is mainly determined by the inductance of the inductor 7 and the capacity of the second capacitor 11'.

In the period (c) (FIG. 21C), when the switching device 6' is turned on, and the polarity of the resonance current is reversed, the resonance current flows in the opposite direction to that of the period (b).

In the period (d), due to the resonance in the period (c), when the voltage on the second capacitor 11' gradually drops below the output voltage of the rectifying device 4, a current flows from the rectifying device 4 to the first capacitor 8 , the primary winding 7-1 of the inductor 7 and the circuit formed by the second switching device 6' charges the first capacitor 8. At this time, as described above, since the capacity of the first capacitor 8 is greatly larger than that of the second capacitor 11', almost no current flows into the second capacitor 11' due to the impedance relationship between the two capacitors.

During period (e) (FIG. 21D), current flows into the parasitic diode 5'-2 and the first capacitor 8 due to the energy stored on the inductor 7. Thereafter, return to the state of period (a).

As described above, the twelfth embodiment operates in the same manner as the Fig. 4 embodiment, can reduce distortion, and can obtain the same effect.

According to the experiment, as shown in Fig. 22B, the distortion of the input current Iin is reduced compared with the input voltage Vin shown in Fig. 22A, and the fluctuation of the lamp current IL shown in Fig. 23B is reduced compared with the input voltage Vin shown in Fig. 23A Also small.

In addition, the waveforms of the drain-source voltage VDS and the drain current ID of the second switching device 6' are the same as those shown in FIG. 24A. In the period (b) when the output voltage of the rectifying device 4 is high, the waveforms of the voltage VDS and the current ID are the same as those shown in FIG. 24B. In the period (c) when the output voltage of the rectifying device 4 is low, the waveforms of the voltage VDS and the current ID are the same as those shown in FIG. 24C.

In addition, the waveforms of the output voltage V4 and the output current I4 of the rectifying device 4 are as shown in FIG. 25A. During the period (b) when the voltage of the commercial AC power supply 1 is low, the waveforms of the voltage V4 and the current I4 are as shown in FIG. 25B. During the period (c) when the output voltage of the rectifying device (c) is high, the waveforms of the voltage V4 and the current I4 are shown in FIG. 25C.

Fig. 26 is a circuit diagram of a thirteenth embodiment of the present invention. In this embodiment, the first capacitor 8' is connected to the second switching device 6' side of the embodiment of Fig. 20 .

When the first switching device 5' is turned on, a current flows through the closed circuit formed by the rectifying device 4, the first switching device 5', the primary winding 7-1 of the inductor 7, the first capacitor 8' and the rectifying device 4, Accordingly, the first capacitor 8' is charged. At this time, a current with improved power factor flows.

When the first switching device 5' is turned off, a current flows through the closed circuit formed by the first capacitor 8', the diode 6'-2, the primary winding 7-1 of the inductor 7 and the first capacitor 8'.

When the second switching device 6' is turned on, a current flows through the closed circuit formed by the first capacitor 8', the primary winding 7-1 of the inductor 7, the second switching device 6' and the first capacitor 8'.

When the second switching device 6' is turned off, a regenerative current flows through the primary winding 7-1 of the inductor 7, the diode 6'-2, the second capacitor 11', the first capacitor 8' and the primary winding 7 of the inductor 7 -1 forms a closed circuit. Consequently, the voltage across the second capacitor 11' rises. When the first switching device 5 ′ is turned on, the voltage on the second capacitor 11 ′ drops to be equal to the output voltage of the rectifying device 4 .

As described above, the thirteenth embodiment operates in the same manner as the embodiment of Fig. 20, and can reduce distortion to obtain the same effect.

Fig. 27 is a circuit diagram of a fourteenth embodiment of the present invention. This embodiment is similar to the embodiment shown in FIG. 26 . However, in this embodiment, the first capacitor 11'' is used as part or all of the second capacitor 11' between the output terminal of the rectifying device 4 and the pair of switching devices 5 and 6. Connected in parallel to the capacitor 11'' is a diode 27 directed in the same direction as the output polarity of the rectifier device 4. In this embodiment, the second capacitor 11 is used to pass high-frequency waves while the resonance effect is basically formed by the capacitor 11'''. Alternatively, a predetermined resonant action may be performed by a combination of capacitors 11'' and 11'. Also, these capacitors may be combined with a second capacitor connected in parallel to any one of the switching devices, and a predetermined resonance action is performed by the three capacitors.

In this embodiment, two or more capacitors 11''' may be provided between the positive and negative output terminals of the rectifying device 4 and the pair of switching devices 5 and 6.

Fig. 28 shows a situation where the present invention is applied to a lighting device. Referring to Fig. 28, reference numeral 261 denotes a lighting fixture, which is mounted directly to the ceiling. A discharge lamp lighting device composed of the discharge lamp lighting devices according to the second to fourteenth embodiments is provided in the lamp 261 . Note that the discharge lamp lighting device does not have to be arranged inside the lamp 261 , and can also be arranged outside the lamp 261 . In addition, although the lighting device in this embodiment belongs to the type that is installed directly on the ceiling, another type of device may also be used.

The present invention is not limited to the above-described embodiments. For example, for the rectifier 4, the high-speed rectifier may be replaced by a low-speed rectifier, and a high-speed diode may be connected to the output side of the low-speed rectifier. In addition, the above-described embodiments can also be appropriately combined with each other. For example, an operation of changing the on/off frequency of each switch and an operation of changing the rate of the conduction cycle can be performed.

The 15th to 24th embodiments in which the discharge lamp lighting device of the 1st to 14th embodiments are further improved will be described below.

Several embodiments obtained by modifying the basic example in consideration of the above points are described below.

Referring now to Fig. 29, a fifteenth embodiment of the present invention will be described. Reference numeral 101 denotes an industrial AC power supply. To this AC power source 101, a filter circuit 105 composed of a common mode choke coil 102, a choke coil 103, a capacitor 104, and the like is connected. To the filter circuit 105 is connected a rectifying device 106 as a full-wave rectifier. The rectifying means is constituted by, for example, a diode having high-speed switching characteristics. In addition, the first and second switching devices 107 and 108 are connected in series between the output terminals of the rectifying device 106 .

A series circuit of a primary winding 109 - 1 of a magnetic leakage type isolation transformer as an inductor 109 and a smoothing capacitor having a larger capacity as a first capacitor 110 is connected to the first switching device 107 in parallel. The first capacitor 110 has a smoothing effect on the output frequency of the rectifying device 106 .

In this embodiment, an output circuit is formed across the inductor 109 . That is, the secondary winding 109-2 of the inductor 109 is used as an output circuit. A discharge lamp 111, for example a fluorescent lamp, is connected to the secondary winding 109-2 as a load. A capacitor 112 for preheating the filament is connected between the filaments of the discharge lamp 111 . In this embodiment, the leakage inductance of the inductor 109 is also used as the current limiting impedance of the discharge lamp 111 .

A resonant capacitor serving as the second capacitor 113 having a smaller capacity is connected in parallel to the second switching device 108 through the primary winding 109 - 1 of the inductor 109 . The capacity of the second capacitor 113 is much smaller than that of the first capacitor 110 . The second capacitor 113 resonates with the inductance of the inductor 109 at the switching frequency of the switching devices 107 and 108 .

Reference numeral 114 denotes a control unit that controls on/off operations of the switching devices 107 and 108 . The control unit 114 turns on/off the switching device pair 107 and 108 alternately at a substantially constant frequency, and controls the conduction period of the switching device 107 so that the peak value of the current flowing in the switching device 107 is a predetermined value. In this embodiment, the control unit includes detection means 114-1 for detecting the current in the switching device 107, means 114 for rectifying the output of the detection means 114-1 to output the current during the period (a) shown in FIG. 31A -2. A comparator 114-4 for comparing the output of the rectifying device 114-2 with the value of the reference signal source 114-3 and an oscillator 114 that outputs a cutoff signal to the switching device 107 according to the output of the comparator 114-4 -5. In this embodiment, the oscillating device 114-5 includes an oscillator 114-6, a flip-flop 114-7 receiving the outputs of the oscillator 114-4 and the comparator 114-4, Q and Q The output buffer pair 114-8a and 114-8b, and an isolation device 114-9 such as a transformer or an optocoupler are interposed between the switching device 107 on the high voltage side and the buffer 114-8a.

In this embodiment, the output frequency or conduction period of the oscillation device 114-5 can be changed according to an external control signal. In this case, for example, the output frequency of the oscillator 114-6 may be changed. Note that the oscillating device 114-5 may be constituted by an integrated circuit as a main part. The oscillating device 114-5 is not limited to the one in this embodiment, and various changes can be made.

The effect of this embodiment will be described below with reference to FIGS. 30A to 33 . In Figures 30A to 31C, Figures 30A and 31A show the voltage on the second capacitor 113; Figures 30B and 31B show the current in the first switching device 107; Figures 30C and 31C show the second switch current within device 108 . 30A to 30C correspond to periods when the unsmoothed DC voltage is relatively high. 31A to 31C correspond to the period when the voltage is lower. Referring to Figures 30A to 31C, the time axis t corresponds to the switching frequency spread. 38 and 39 show the voltage between the outputs of the rectifying device 106 and the lamp current in the discharge lamp 111, respectively. Referring to FIGS. 38 and 39 , the time axis t corresponds to the frequency of the AC source 101 .

The basic operation of this embodiment is the same as that of the second embodiment shown in FIG. 5 . In this embodiment, when the peak value of the current discharged by the first capacitor 110 through the switching device 107 reaches a predetermined value, that is, reaches the value of the reference signal source 114-3 (level A in FIGS. 30B and 31B ), the oscillation means Switching device 107 is turned off. For this operation, the closed circuit formed by the inductor 109, the second capacitor 113 and the parasitic diode of the second switching device 108 resonates, and when the second switching device 108 is turned on, the resonance current is reversed. In this case, since the peak value of the current flowing through the switching device 107 is controlled at a predetermined value before resonance occurs, the peak value of the resonance voltage is also constant. Since the voltage on the first capacitor 110 is constant, as shown in FIG. 32, if the power supply voltage does not change and the like, the voltage of the rectifying means 106 is also kept constant. Therefore, since the voltage applied to the switching devices 107 and 108 is constant, the switching devices 107 and 108 are not broken down due to overload. In addition, as shown in FIG. 33, the lamp current hardly contains low-frequency (input frequency of the rectifying means) ripple. Note that in this case, as in the case shown in Figure 3, the input current waveform is a sine wave.

In a period in which the peak value of the output voltage (unsmoothed DC voltage) of the rectifying device 106 is small ( FIGS. 31A to 31C ), the conduction time of the first switching device 107 is shorter than in the period in which the peak is large. , so the conduction period of the second switching device 108 is extended accordingly.

Fig. 34 is a circuit diagram of a sixteenth embodiment of the present invention. The same reference numerals in FIG. 34 as those in FIG. 29 denote the same components, and descriptions of these reference numerals are omitted (the same applies to the following embodiments). The difference between this embodiment and the embodiment in FIG. 29 lies in the control unit 161 . The control unit 161 includes a current detecting device 161-1 for detecting the current in the second switching device 108 and a rectifying device 161-2 for outputting an initial value of the resonance current according to the detection signal of the current detecting device 161-1. As shown in FIG. 6B , the rectifying device 161 - 2 rectifies and outputs the current flowing during the period (b). The control unit 161 also includes a delay means 161-3, which maintains the output of the rectifying means 161-2 and performs an output operation during the timed turn-on of the first switching device 107 in one or several cycles after the maintaining operation. The control unit 161 further includes a comparison device 161-5 for comparing the output of the delay device 161-3 with the value of the reference signal 161-4 and an oscillation device 161 for cutting off the first switching device 107 according to the output of the comparison device 161-5. -6. The oscillating device 161-6 may be the one shown in FIG. 29 .

In this embodiment, the peak value of the discharge current flowing in the first switching device 107 is detected and used as the initial value of the resonant circuit flowing in the second switching device 108 . As shown in Figs. 6A to 6E, these values are equal. Therefore, as shown in the figure, according to the control operation in the embodiment shown in FIG. 29, the control of the peak value of the discharge current flowing through the second switching device 108 is delayed by one or several cycles, but the same value as that of FIG. 29 can be obtained. The embodiment shown has the same effect.

Fig. 35 is a circuit diagram of a seventeenth embodiment of the present invention. This embodiment is also different from the control unit 171 of the embodiment shown in FIG. 29 . More specifically, in addition to the components included in the control unit 114 of FIG. 29 , the control unit 171 also includes a circuit for detecting the voltage between the output terminals of the rectifying device 106, that is, the voltage between the first and second capacitors 110 and 113. Voltage detecting device 117-1, for taking out the detection signal of voltage detecting device 171-1 and delaying the device 171-2 for a period of time by such as integrated circuit etc. this signal, and for connecting the output of device 171-2 with the reference signal The comparator 171-4 compares the value of the source 171-3. The means 171 - 2 can adapt to the variation of the low frequency voltage whose frequency is almost equal to the output frequency of the rectifying means 106 . The oscillation device 114-5 shortens the conduction period of the second switching device 10 when the output voltage increases and lengthens the conduction period of the second switching device 108 when the output voltage decreases according to the signal of the comparator 171-4. Therefore, in this embodiment, the switching frequencies of the first and second switching devices 107 and 108 can be changed.

The effect of this embodiment will be described below with reference to FIGS. 36 and 37. FIG.

36 and 37 show the current flow in the second switching device 108 . FIG. 36 shows the current flow in the case of a high voltage between the outputs of the rectifier device 106 . Fig. 37 shows the current at this lower voltage. The control unit 171 utilizes the effect of the voltage detection device 171-1, and when the voltage between the output terminals of the rectifying device 106, that is, the voltage between the first and second capacitors 110 and 113 ends, starts to have a low-frequency voltage increase, shorten the second capacitor. The conduction period of the second switching device 108 . Therefore, the charging cycle of the first capacitor 110 is shortened, and the charging amount is reduced. For this, the low frequency voltage in the voltage between the first and second capacitors 110 and 113 is reduced. Contrary to this, when the voltage between the output terminals of the rectifying means 106, that is, the low-frequency voltage in the voltage between the first and second capacitors 110 and 113 decreases, the conduction period of the second switching device 108 is extended. Therefore, the charging cycle of the first capacitor 110 is prolonged, and the charging amount is increased.

Thus, when the voltage between the output terminals of the rectifying device 106, that is, the voltage between the first and second capacitors 110 and 113 starts to change due to a change in the voltage of the AC power source 110, a change in load, and the like, the control unit 171 operates as The above method works to control the voltage at a constant value.

38A to 38E show the test results of this embodiment. Figure 38A shows the voltage on the first capacitor 110; Figure 38B shows the voltage across the rectifier 106; Figure 3C shows the distortion coefficient of the input current; Figure 38D shows the lamp power; Figure 38E shows the second The conduction period of the switching device 108 . The abscissa represents the voltage (V) of the AC power supply.

The following are the test conditions:

AC power supply 101: 200V (effective value), 50Hz

Discharge lamp 111: 40W fluorescent lamp × 2

(FLR40SW/M/36 manufactured by Toshiba Lighting Co., Ltd.)

Switching frequency of the first and second switching devices 107 and 108: about 35KHz

First capacitor 110: 220 μF

Second capacitor 113: 16.6 μF

As can be seen in FIGS. 38A to 38E, even if the voltage on the first capacitor 110 increases/decreases with respect to the rated voltage of 200V, the peak value of the current in the first switching device 107 is always set at a predetermined value, and according to The voltage across the rectifying means 106 controls the conduction period of the second switching device 108 (FIG. 38E). For this operation, the voltage across the rectifying means 106 (FIG. 38B) can be maintained at a substantially constant voltage of 560V. It is therefore also possible to maintain the lamp power (FIG. 38D) at a substantially constant power of 60W. In addition, the distortion coefficient of the input current (FIG. 38C) can be kept at a substantially constant value of about 6.5%. As can be understood from the relationship when the voltage of the AC power source 101 rises above the rated voltage shown in FIGS. 38A and 38E , the conduction period of the second switching device 108 is shortened to lower the voltage of the first capacitor 110 .

Fig. 39 is a circuit diagram of an eighteenth embodiment of the present invention. In this embodiment, in addition to the operation of the embodiment shown in FIG. 29 , the predetermined value of the conduction period of the first switching device 107 is also determined according to the voltage change between the output terminals of the rectifying device 106 . More specifically, the control unit 411 includes a voltage detecting device 411-2 for detecting the voltage between the output terminals of the rectifying device 106, and rectifies the detection signal of the voltage detecting device 411-1, and outputs a signal with a predetermined time constant. Synthetic signal output means 411-1. The output of the rectifying means 114-2 is changed according to the output of the output means 411-1. More specifically, when the detection signal of the voltage detecting means 411-1 starts to rise, the output of the rectifying means 114-2 is changed. Therefore, in this case, the conduction period of the first switching device 107 becomes relatively short, and the resonance voltage varies. In addition, when the detection signal of the voltage detection means 411-1 starts to rise, the opposite operation is performed. For this operation, the voltage at the output of the rectifier device 106 can be kept constant.

Fig. 40 is a circuit diagram of a nineteenth embodiment of the present invention. In this embodiment, parallel circuits of bipolar transistors and diodes are used as the first and second switching devices 107' and 108

In addition, a saturated current transformer 422 is used as means for detecting the peak value of the current in the first switching device 107'. That is, the input winding 422-1 of the saturated current transformer 422 is connected to the input winding 109-1 of the inductor 109 in series. Its output windings 422-2 and 422-3 are arranged between the bases and emitters of the switching devices 107' and 108', respectively. Although the parallel circuit for adjusting impedance composed of capacitors and diodes is not shown in the figure, if necessary, they can be connected in series to the output windings 422-2 and 422-3 respectively, and the discharge circuits can be connected in parallel connected to this capacitor.

In this embodiment, the voltage detecting means 423 for detecting the voltage on the rectifying means 106, that is, the summed voltage of the first and second capacitors 110 and 113 is composed of a rectifier 423-1, a smoothing capacitor 423-2, and a voltage dividing circuit 423 -3 composition. This embodiment further includes an error amplifier 425 receiving the output of the voltage dividing circuit 423 - 3 and the value of the reference source 424 , a voltage dividing voltage 426 outputting a signal according to the output of the error amplifier 425 , and a transistor 427 . The base current of the transistor 427 is controlled by the output of the voltage divider circuit 426 to change its conductivity. In this manner, transistor 427 operates in the same manner as a variable resistor to control the conduction period of switching device 108'.

In this embodiment, when the value of the current flowing in the switching device 107' reaches a predetermined value, the current transformer 422 is saturated. Since the current flowing in the switching device 107' basically increases with the voltage on the first capacitor 110 and the impedance of the inductor 109, the saturation time of the saturated current transformer 422 can be set in advance to be the same as that flowing in the switching device 107'. The time when the peak value of the current reaches the predetermined value coincides. When the current transformer 422 is saturated, the switching device 107' is turned off and the switching device 108' is turned on. Additionally, when the current transformer 422 is saturated by the current flowing in the switching device 108', the switching device 108' is turned off and the switching device 107' is turned on. Then, repeat this operation. Therefore, during the peak amplification period of the unsmoothed DC voltage of the rectifying device 106, the current value flowing in the first capacitor 110 and the second switching device 108' is relatively large. As a result, the current transformer saturates faster and, therefore, the conduction period of the switching device 108' is set shorter. In contrast to this, the conduction period of the switching element 108' is set to be longer in periods in which the peak value of the unsmoothed DC voltage of the rectifier device 106 is smaller. For this operation, the conduction periods of the first and second switching devices 107' and 108' are controlled according to the relationship shown in FIG. If an overcurrent flows due to an external surge voltage during the turn-on operation, the current transformer 422 is quickly saturated to turn off the second switching device 108', thereby preventing the overcurrent from continuing to flow.

At the same time, the voltage across the rectifying device 106 is detected by the voltage detecting device 423, and the conductivity of the transistor 427 is controlled according to an error signal based on a predetermined value. Specifically, for example, when the voltage across the rectifying device 106 decreases due to a change in power supply voltage or a change in load, the conductivity of the transistor 427 is reduced. When the conductivity of the transistor 427 decreases, its resistance increases, prolonging the conduction period of the second switching device 108'. For this operation, the charging time of the first capacitor 110 is also extended to provide the voltage across the first capacitor 110 .

Therefore, in this embodiment, the resonance voltage can be made constant, and the voltages across the first and second capacitors 110 and 113 can also be made constant. Therefore, it is possible to prevent voltage variations across the first capacitor 110 from being caused by power supply voltage variations, load variations, and the like.

In an example not according to the present embodiment, although the voltage of the first capacitor 110 also hardly changes with respect to the switching frequency due to the smoothing effect, the voltage will vary with changes in the power supply voltage or the like. For this reason, if eg the supply voltage varies and rises, the voltage of the first capacitor 110 will be constant at a voltage higher than a predetermined value. If the supply voltage decreases, the voltage of capacitor 112 will be constant at a voltage lower than a predetermined value. When this voltage is constant at a high voltage, an excessive voltage will be applied across the switching device. When the voltage is constant at low voltage, the predetermined load power cannot be supplied.

In this embodiment, the device for detecting and controlling the voltage across the rectifying device can be omitted.

Fig. 41 is a circuit diagram of a twentieth embodiment of the present invention. Fig. 41 shows only the main part of this embodiment, and the remaining parts are omitted. Note that the structure of omitted parts may be the same as the embodiment shown in FIG. 40 . In this embodiment, means for detecting the output voltage of the AC power source 101 (the input voltage of the rectifying means 106) is used as the means 431 for controlling the conduction period of the switching device 108. To detect the output voltage of the AC power source 101, the rectifiers 431-1 and 431-2 are connected to the output terminals of the AC power source 101, and the outputs of the rectifiers 431-1 and 431-2 are input to the time constant circuit 431-3. The output of the time constant circuit 431-3 is input to the same error amplifier 425 as in FIG. 40 . Similar to the error amplifier of FIG. 40, the error amplifier 425 compares the output of the time constant circuit 431-3 with the value of the reference signal source 424, and controls the driving circuit 426 and the transistor 427.

Therefore, in this embodiment, even if the output voltage of the AC power source varies, the output voltage can be kept constant.

Fig. 42 is a circuit diagram of a twenty-first embodiment of the present invention. In this embodiment, when it is detected that the output current of the rectifying device 106 flows for a predetermined time, the second switching device 108 is turned off. More specifically, a current detection device 411, a delay device 442, a reference signal source 443 and a comparator 444 are additionally provided to control the oscillation device 114-5. Since the effects of the present embodiment can be easily understood from the above description, descriptions of the effects are omitted. Although not shown in the figure, the resonance voltage can be made constant by the same control means as shown in Fig. 29, 34 or 39.

Fig. 43 is a circuit diagram of a twenty-second embodiment of the present invention. In this embodiment, the conduction period of the pair of switching devices 107 and 108 is controlled according to the power supplied to the fluorescent lamp 111 as a load. More specifically, current detection means 451 and voltage detection means 452 are provided, and the oscillation means 114-5 is controlled by the control means 153 which receives the detection outputs of these detection means. In this embodiment, too, the resonance voltage can be made constant by the same control means as in Fig. 29, 34 or 39.

Since the effects of the present embodiment can be easily understood from the above description, descriptions of the effects are omitted. In this embodiment, the conduction period of the switching device pair 107 and 108 can be controlled only according to the lamp current or the lamp voltage. In addition, it is also possible to control the conduction period of only one of the switching devices. Also, the switching frequency can be changed.

Fig. 44 is a circuit diagram of a twenty-third embodiment of the present invention. Fig. 44 only shows the main part of this embodiment, and the remaining components are omitted. In this embodiment, the connection relationship between the first and second capacitors 110 and 113 is reversed in the vertical direction with respect to FIG. 29 . Therefore, the connection relationship of the first and second switches 107 and 108 is also reversed. In addition, in the present embodiment, after the discharge current of the first capacitor 110 flows to the first switching device 107 through the inductor 109 for a predetermined period of time, the first switching device 107 is turned off. More specifically, this embodiment includes a current detection device 461, a comparison device 462 for detecting whether the detection value obtained by the current detection device 461 passes through a zero cross point and rises, and a comparison device 462 for detecting that the detection value obtained by the current detection device 461 passes through zero. The timing means 463 which controls the oscillating means 114-5 after the crossing point.

Effects of the present embodiment will be described with reference to FIG. 45 . FIG. 45 shows the current flowing in the first switching device 107 . The comparing means 462 detects the zero-crossing time t1 in FIG. 45 . The timing means 463 turns off the first switching device 107 after the zero crossing time t1. Therefore, as seen from the above description, the resonance voltage is kept constant.

In this embodiment, after the current flowing in the parasitic diode of the first switching device 107 stops flowing, the first switching device 107 may be turned off for a predetermined period of time. In this case, if the first switching device 107 is a field effect transistor, the circuit shown in FIG. 44 can be used without modification. If the first switching device 107 is a bipolar transistor, the point in time when the current flowing in the cross-coupled diode stops flowing can be detected.

Fig. 46 is a circuit diagram of a twenty-fourth embodiment of the present invention. In this embodiment, the second switching device 108 is turned off after a predetermined period of time when current flows into the second switching device 108 . More specifically, the present embodiment includes current detecting means 481 for detecting the current flowing in the second switching device 108, integrating means 482 for integrating the detection value of the current detecting means 481, and integrating the output of the integrating means 482 Comparing means 483 for comparison with a reference value. The oscillating means 114-5 is controlled by the output of the comparing means 483. Note that, for example, the oscillator 114-5 outputs a signal with a constant frequency.

Effects of the present embodiment are described with reference to FIGS. 47A to 37C. FIG. 47A shows the current flowing in the second switching device 108 ; FIG. 47B shows the current flowing in the first switching device 107 ; and FIG. 47C shows the output current of the rectifying device 106 . For example, if the comparison means 483 is set so that when the integral value reaches the shaded region of the current waveform as shown in Figure 47A, the output signal makes the second switching device 108 cut off, then as shown in Figure 47C, the rectification means 106 can reliably supply current. That is, the rectifying device 106 may supply current after the peak of the resonance current occurs. For this kind of operation, high input power factor can be achieved, input current distortion can be reduced, and constant output voltage can be obtained.

Fig. 48 is a perspective view of the present invention applied to a lighting device. Reference numeral 201 denotes a lighting fixture of the type directly mounted on the ceiling. The discharge powder 111 is installed on the lamp 201 . A discharge lamp lighting device as in one of the fifteenth to twenty-fourth embodiments is provided in the lamp 201 as the discharge lamp lighting device. Note that the discharge lamp lighting device does not necessarily need to be arranged inside the lamp 201 , it can be arranged outside the lamp 201 . Although the lighting device of this embodiment is of the type directly mounted on the ceiling, another type may be used.

Modifications to the present invention are not limited to the above-described embodiments. For example, the high-speed rectifier can be replaced by a low-speed rectifier, a high-speed diode can be connected to the output side of the low-speed rectifier. In addition, the above-mentioned embodiments may be appropriately combined with each other.

FIG. 49 shows the configuration of a main part of a discharge lamp lighting device applied to a DC load circuit 551. As shown in FIG.

In this structure, the DC load circuit 551 is connected to the secondary winding side of the transformer 7" through the rectifying circuit 550, and the primary winding of the transformer is connected to the nodes of the above-mentioned first and second switching devices 5' and 6' and the above-mentioned first One and the second capacitors 8 and 11 at the node.

The DC load circuit 551 includes resistive loads as well as common electronic devices and circuits that require DC power.

Therefore, as described above, according to the present invention, the following effects can be obtained.

According to the first or second aspect of the present invention, since the rectifying means can supply the input current substantially over the entire period of the rectified unsmoothed DC voltage, a smooth output can be obtained, and the waveform of the input current of the AC power source can be made to be the same as Similar to a sine wave, reducing distortion.

According to the third aspect of the present invention, by changing the conduction period of one of the switching devices, the energy stored in the inductor can be changed to adjust the output voltage. In addition, since the switching frequency is basically constant, even if the switching frequency increases, the switching loss will not increase.

According to the fourth aspect of the present invention, the output voltage can be adjusted in the same way as the third aspect of the present invention by changing the conduction cycle rate of the switching device pair. In addition, a sufficient smooth output voltage can be obtained by changing the conduction period of the switching device according to the peak value of the voltage output in each half cycle of the AC power supply.

According to the fifth and sixth aspects of the present invention, by changing the switching frequency, the absolute conduction period of another switching device can be changed, and the output voltage can also be changed.

According to the seventh aspect of the present invention, since the second capacitor is connected in parallel to the other switching device and the inductor, a simple arrangement can be realized.

According to the eighth aspect of the present invention, since the second capacitor is connected between the output terminals of the rectifying means, similarly to the seventh aspect of the present invention, a simple arrangement can be realized.

According to the ninth aspect of the present invention, since the second capacitor is connected between the rectifying means and the pair of switching devices, a simple arrangement can be realized similarly to the seventh aspect of the present invention.

According to the tenth aspect of the present invention, the output circuit includes an impedance circuit whose impedance decreases as frequency increases. Therefore, even if the oscillation frequency is increased, the impedance of the line for reducing distortion can be kept small, so that a sufficiently small resonance current can be obtained.

According to the eleventh aspect of the present invention, since the drive transformer stops oscillation of the first and second switching devices when the load is removed, an increase in voltage applied to the first and second switching devices can be prevented.

According to the twelfth aspect of the present invention, output fluctuation can be reduced to improve luminous efficiency, thereby reducing light fluctuation.

According to the thirteenth aspect of the present invention, since the conduction period of the other switching device is set shorter than the lamp on-period during the predetermined period of the starting operation of the discharge lamp, the discharge lamp is started after the filament is sufficiently preheated. Therefore, shortening of the service life of the discharge lamp can be prevented.

According to the fourteenth aspect of the present invention, the luminous efficiency is improved, and the fluctuation of the lamp current is reduced, thereby reducing the light fluctuation.

According to the 15th and 16th aspects of the present invention, since the rectifying means can supply the input current substantially over the entire period of the rectified unsmoothed DC voltage, the waveform of the input current of the AC power source can be made to be similar to a sine wave, reducing distortion. In addition, since the current in the first switching device which determines the magnitude of the resonance voltage is directly controlled, the resonance voltage can be controlled at an arbitrary value or made constant.

In the discharge lamp lighting device according to the seventeenth aspect of the present invention, since the conduction period of the first switching device is controlled so that the peak value of the current flowing in the first switching device becomes a predetermined value, the resonance voltage can be made constant. . This operation prevents excessive voltage from being applied to the switching device and causing it to break down. Moreover, this operation also makes it unnecessary to use a switching device having a high breakdown voltage, thus preventing an increase in cost.

In the discharge lamp lighting device according to the eighteenth aspect of the present invention, since the integral of the current flowing in the first switching device is controlled to a predetermined value, substantially the same effects as those of the seventeenth aspect can be obtained.

In the discharge lamp lighting device according to the nineteenth aspect of the present invention, since the initial value of the resonance current flowing in the first switching device is controlled at a predetermined value, substantially the same effects as those of the seventeenth aspect can be obtained.

In the discharge lamp lighting apparatus according to the twentieth aspect of the present invention, the predetermined value of the current which determines the conduction period of the first switching device is changed according to the voltage values across the first and second switching devices. Therefore, the voltages on the first and second switching devices can be kept constant regardless of the variation of the power supply voltage, the variation of the load, and the like.

In the discharge lamp lighting device according to the 21st aspect of the present invention, since the second switching device is turned off after a predetermined time period of current flowing through the second switching device, the charging current can be reliably supplied to the first capacitor. Therefore, the power factor can be improved and the input current distortion can be reduced.

In the discharge lamp lighting device according to the 22nd aspect of the present invention, since the second switching device is turned off for a predetermined time after the peak value of the resonance current flows, the charging current can be reliably supplied to the first capacitor. Therefore, the same effects as those of the twenty-first aspect can be obtained.

In the discharge lamp lighting device according to the 23rd aspect of the present invention, since the input/output current flows for a predetermined time in the rectifying means, the same effects as those of the 21st and 22nd aspects can be obtained.

In the discharge lamp lighting device according to the twenty-fourth aspect of the present invention, since the conduction period of the second switching device is controlled based on the voltage value corresponding to the voltage on the first capacitor, it is possible to control the charge amount of the first capacitor , to keep the voltage on the first capacitor constant. With this mode of operation, even if the power supply voltage varies, the voltage on the first capacitor can be kept constant, and the voltage applied to the load can also be kept constant.

In the discharge lamp lighting device according to the twenty-fifth aspect of the present invention, since the conduction period of the second switching device is controlled according to the AC power supply voltage, by controlling the charge amount of the first capacitor, the voltage on the first capacitor can be made constant. With this mode of operation, even if the power supply voltage varies, the voltage on the first capacitor can be kept constant, and the voltage applied to the load can also be kept constant.

In the discharge lamp lighting device according to the twenty-sixth aspect of the present invention, since the conduction period of the second switching device is controlled based on the output of the output circuit, the power supplied to the load can be made constant.

According to the twenty-seventh aspect of the present invention, in order to apply the present invention to a discharge lamp lighting device, a discharge lamp is used as a load of the discharge lamp lighting device. Therefore, output fluctuation is further reduced to improve luminous efficiency and reduce light fluctuation.

According to the 28th aspect of the present invention, in order to apply the present invention to a lighting device, the discharge lamp lighting device according to the 21st aspect is provided in the device body. Therefore, luminous efficiency is improved, distortion of lamp current is reduced, and light fluctuation is reduced.

In the discharge lamp lighting device according to the 29th aspect of the present invention, the high frequency voltage generated by the resonance system of the resonance capacitor means and the inductor means is formed in the AC voltage rectified by the rectifying means. For this operation, it makes the rectified output voltage equal to the input voltage, ensuring that there is input current even when the AC voltage is low, thereby reducing input current distortion and reducing the harmonic component of the input current.

Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention, in its broadest aspects, should not be limited by the specific details shown and described herein. Thus, various modified discharge lamp lighting devices can be made without departing from the spirit and scope of the general inventive concept of the invention as defined in the appended claims and their equivalents.

Claims (18)

1, a kind of lighting apparatus for discharge lamp, has output voltage rectification with AC power, export not level and smooth direct voltage rectifying device, be one another in series is arranged between the output of described rectifying device with connecting, replace first and second switching devices of break-make with the frequency higher than the output frequency of described rectifying device, and first capacitor of the level and smooth usefulness that is arranged in parallel with described first switching device, it is characterized in that, also comprise:

Series connection is arranged at the inductor between described first switching device and first capacitor;

Connect with described inductor be provided with, corresponding to the break-make of described first and second switches, with second capacitor of the collaborative resonance of described inductor; And

With described inductor discharge lamp that be arranged in parallel, that be carried out High frequency power.

2. lighting apparatus for discharge lamp, have the direct voltage that the output voltage rectification of AC power output is not level and smooth rectifying device, be one another in series is arranged between the output of described rectifying device with connecting, replace first and second switching devices of break-make with the frequency higher than the output frequency of described rectifying device, and first capacitor of the level and smooth usefulness that is arranged in parallel with described first switching device, it is characterized in that, also comprise:

Series connection is arranged at the inductor between described first switching device and first capacitor;

Connect with described inductor be provided with, corresponding to the break-make of described first and second switches, with second capacitor of the collaborative resonance of described inductor;

Control unit, link to each other with described first switching device, discharging current that be used for discharging according to described first capacitor and that flow in described first switching device is controlled the turn-on cycle of described first switching device, to control the resonance potential value that described inductor and described second capacitor produce;

Output circuit is used for obtaining high frequency output based on the resonance of described inductor and the generation of described second capacitor; And

With described inductor discharge lamp that be arranged in parallel, that be carried out High frequency power.

3. device as claimed in claim 1 or 2 is characterized in that, further comprises switch controlling device, is used to make described first and second switching devices with constant basically frequency conduction and cut-off, and can change the turn-on cycle rate of described switching device.

4. device as claimed in claim 1 or 2, it is characterized in that, further comprise switch controlling device, be used to make described first and second switching devices to end with substantially invariable frequency conducting, and can change the turn-on cycle rate of described first and second switching devices, described switch controlling device shortens the turn-on cycle of described second switch device when the electric output peak value of the every half period of described AC power is big, when this peak value hour, prolong this turn-on cycle.

5. device as claimed in claim 1 or 2 is characterized in that, further comprises the switch controlling device that can change the described first and second switching device conduction and cut-off frequencies.

6. device as claimed in claim 5, it is characterized in that described first and second switching devices are in the cycle less corresponding to the peak value of the output voltage of described rectifying device, with lower frequency conduction and cut-off, when this peak value increases, with higher frequency conduction and cut-off.

7. device as claimed in claim 1 or 2 is characterized in that, described second capacitor is parallel-connected on described second switch device and the described inductor.

8. device as claimed in claim 1 or 2 is characterized in that, described second capacitor is arranged between the output of described rectifying device.

9. device as claimed in claim 1 or 2, it is characterized in that, described output circuit is coupled on the described inductor, the elementary winding of a transformer is connected in series in load, power to the load by described output circuit, described first and second switching devices are carried out drive controlling by the output of described Secondary winding of transformer.

10. device as claimed in claim 1 or 2 is characterized in that, further comprises the discharge lamp as load that is arranged in the described output circuit.

11. device as claimed in claim 10 is characterized in that, described discharge lamp is installed on the lighting.

12. device as claimed in claim 2 is characterized in that, described control unit is controlled the turn-on cycle of described first switching device, and making discharging current that first capacitor discharges and that flow in described first switching device is a predetermined value.

13. device as claimed in claim 2 is characterized in that, described control unit is controlled the turn-on cycle of described first switching device, and making described first capacitor is a predetermined value by the discharging current that described inductor and described first switching device discharge.

14. device as claimed in claim 2 is characterized in that, described control unit changes the predetermined value of the current value of the described first switching device turn-on cycle of decision according to the magnitude of voltage on described first and second switching devices.

15., it is characterized in that described control unit flows into described rectifying device at one of input and output electric current at least ends described second switch device after one period scheduled time as claim 2,12,13 or 14 described devices.

16., it is characterized in that described control unit is according to the turn-on cycle of controlling described second switch device corresponding to the magnitude of voltage of the voltage on described first capacitor as claim 2,12,13 or 14 described devices.

17., it is characterized in that described control unit is controlled the turn-on cycle of described second switch device according to ac voltage as claim 2,12,13 or 14 described devices.

18., it is characterized in that described control unit is controlled the turn-on cycle of described second switch device according to the output of described output circuit as claim 2,12,13 or 14 described devices.

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