JP2011054533A - Device for lighting electrodeless discharge lamp, and luminaire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrodeless discharge lamp lighting device, along with a luminaire, capable of suppressing generation of spike current. <P>SOLUTION: In a dimming operation wherein a lighting-up period T on for enlarging output power to an induction coil at a level of lighting up an electrodeless discharge lamp and a lighting-out period T off for lessening the output power to the induction coil at a level of lighting out the electrodeless discharge lamp are periodically and alternately repeated at sufficiently-high frequency at a level of not recognizing blinking with human eyes, switching timing from the lighting-up period T on to the lighting-out period T off is set up to be a zero-crossed point of output voltage to the induction coil. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electrodeless discharge lamp lighting device and a lighting fixture.

  Conventionally, an electrodeless discharge lamp lighting device that turns on an electrodeless discharge lamp by supplying high-frequency power to an induction coil arranged close to the electrodeless discharge lamp and generating plasma by a high-frequency electromagnetic field in the electrodeless discharge lamp. Is provided. This type of electrodeless discharge lamp lighting device includes a resonance unit that forms a resonance circuit together with an induction coil, and a switching unit that is interposed between the DC power source and the resonance unit. By periodically switching the connection, the resonance of the resonance circuit converts the DC power of the DC power source into high-frequency power and supplies it to the induction coil.

  In this type of electrodeless discharge lamp device, as a method of realizing a so-called dimming operation for reducing the light output, there is a method of intermittently lighting the electrodeless discharge lamp (for example, see Patent Document 1). That is, a lighting period in which the output power to the induction coil is increased to the extent that the electrodeless discharge lamp is turned on, and a turn-off period in which the output power to the induction coil is reduced to the extent that the electrodeless discharge lamp is turned off. And alternately repeat periodically at a sufficiently high frequency that it cannot be recognized as blinking. In this method, the light output of the electrodeless discharge lamp can be changed by changing the ratio of the lighting period to the total of the lighting period and the extinguishing period (that is, on-duty). The change of the output power as described above is realized by changing the frequency of operation of the switching unit with respect to the resonance frequency of the resonance circuit formed by the induction coil and the resonance unit.

  As a method of realizing the dimming operation, there is a method of reducing the light output of the electrodeless discharge lamp by reducing the output power to the induction coil, in addition to the method of intermittent lighting as described above. However, since the lighting of the electrodeless discharge lamp cannot be maintained when the output power to the induction coil is reduced to some extent, the method of reducing the light output by reducing the output power as described above can achieve the lower limit of the light output that can be realized. Will be relatively high. On the other hand, if the method is based on intermittent lighting, there is an advantage that the lower limit of the light output that can be realized is lower than the method based on a decrease in output power.

JP 2000-353600 A

  However, in the intermittent lighting of the electrodeless discharge lamp as described above, if the transition from the lighting period to the extinguishing period is made at a point other than the zero crossing point of the output voltage to the induction coil, a spike current is generated, causing electromagnetic noise. There was a possibility.

  This invention is made | formed in view of the said reason, The objective is to provide the electrodeless discharge lamp lighting device and lighting fixture which generation | occurrence | production of a spike current can be suppressed.

  According to the first aspect of the present invention, there is provided an induction coil disposed in proximity to the electrodeless discharge lamp, a resonance unit that constitutes a resonance circuit together with the induction coil, and a DC power source and the resonance unit interposed between the DC power source and the resonance unit. A switching unit that converts DC power input from a DC power source into AC power by periodically switching the electrical connection and supplies the AC power to the induction coil, and a control unit that controls the switching unit, A lighting period in which the switching unit is controlled to increase the output power from the resonance unit to the induction coil to such an extent that the electrodeless discharge lamp is turned on, and the output power from the resonance unit to the induction coil to the extent that the electrodeless discharge lamp is turned off. A dimming operation that periodically and alternately turns off the non-lighting period that controls the switching unit so as to reduce the timing, and the timing of switching from the lighting period to the light-off period in the dimming operation, Characterized by a zero-cross point of the output voltage to the induction coil from the exciting units.

  According to the present invention, the generation of spike currents can be suppressed as compared with the case where switching from the lighting period to the extinguishing period is performed at a point other than the zero cross point of the output voltage from the resonance unit to the induction coil.

  According to a second aspect of the present invention, in the first aspect of the invention, the control unit continues the output of AC power from the resonance unit to the induction coil even during the light extinction period of the dimming operation. The timing of switching from the light-off period to the light-on period is a zero cross point of the output voltage from the resonance unit to the induction coil.

  According to the present invention, the generation of spike currents can be suppressed as compared with the case where switching from the extinguishing period to the lighting period is performed at a point other than the zero cross point of the output voltage from the resonance unit to the induction coil.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the control unit receives a dimming signal for instructing the light output of the electrodeless discharge lamp from the outside, and adjusts the light output of the electrodeless discharge lamp. The duration of the lighting period and the duration of the extinguishing period are respectively determined by calculation so as to obtain an optical output instructed by the optical signal.

  Invention of Claim 4 is equipped with the electrodeless discharge lamp lighting device of any one of Claims 1-3, and the fixture main body which hold | maintains an electrodeless discharge lamp and an electrodeless discharge lamp lighting device, respectively. It is characterized by.

  According to the first aspect of the present invention, the control unit sets the timing of switching from the lighting period to the extinguishing period in the dimming operation as the zero cross point of the output voltage from the resonance unit to the induction coil. As compared with the case where the switching from the lighting period to the extinguishing period is performed at a point other than the zero cross point of the output voltage to the output, the occurrence of spike current is suppressed.

  According to the second aspect of the present invention, the control unit sets the timing of switching from the turn-off period to the lighting period in the dimming operation as the zero cross point of the output voltage from the resonance unit to the induction coil. As compared with the case where the switching from the extinguishing period to the lighting period is performed at a point other than the zero cross point of the output voltage to the output, the occurrence of spike current is suppressed.

(A) (b) is explanatory drawing which shows the waveform of the both-ends voltage of the induction coil in embodiment of this invention, respectively, (b) is the state which reduced the optical output of the electrodeless discharge lamp rather than (a). Show. It is a circuit block diagram which shows the same as the above. It is explanatory drawing which shows the relationship between an operating frequency and output electric power in the same as the above. It is explanatory drawing which shows the time change of an operating frequency in the same as the above. (A) (b) is explanatory drawing which shows the time change of the on-off state of each switching element of the switching part in each same as the above, (b) shows the state which reduced the optical output rather than (a). It is explanatory drawing which shows the waveform of the both-ends voltage of the induction coil in the example of a change same as the above. It is explanatory drawing which shows the relationship with the light output about each of the lighting maintenance frequency | count and the length of a light extinction period in the example of FIG. It is a circuit block diagram which shows another example of a change same as the above. It is explanatory drawing which shows the relationship between a DC output voltage and an optical output in the example of FIG. It is the partially broken front view which shows an example of the lighting fixture using the same. It is a front view which shows another example of the lighting fixture using the same as the above.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  In the present embodiment, as shown in FIG. 2, the induction coil 2 disposed close to the electrodeless discharge lamp 1 and the DC power input from the DC power supply 3 are converted into high-frequency AC power and output to the induction coil 2. Thus, an inverter unit 4 for lighting the electrodeless discharge lamp 1 and a control unit 5 for controlling the inverter unit 4 are provided. As the DC power supply 3, for example, a known DC power supply circuit or a battery can be used.

  More specifically, the electrodeless discharge lamp 1 has a discharge gas containing mercury vapor and a rare gas in a hollow bulb made of a transparent material such as glass and provided with a fluorescent film on the inner surface. It is enclosed. That is, when arc discharge is generated in the bulb by the high frequency electromagnetic field generated by the induction coil 2, the discharge gas generates ultraviolet rays, and the ultraviolet rays are converted into visible light by the fluorescent substance. The electrodeless discharge lamp 1 emits light. Since the electrodeless discharge lamp 1 as described above can be realized by a well-known technique, detailed illustration and description thereof will be omitted.

  The inverter unit 4 is interposed between the resonance unit 41 constituting the resonance circuit together with the induction coil 2 and the DC power source 3 and the resonance unit 41 to periodically switch the connection between the DC power source 3 and the resonance unit 41. A switching unit 42 that causes the induction coil 2 to output AC power generated by resonance of the resonance circuit.

  The switching unit 42 is a drive circuit for periodically turning on and off the switching elements Q1 and Q2 so that the two switching elements Q1 and Q2 are alternately turned on, and a series circuit of the two switching elements Q1 and Q2. Circuit 42a. The frequency at which the drive circuit 42a turns on and off the switching elements Q1 and Q2 (that is, the frequency of the output voltage from the resonance unit 41 to the induction coil 2; hereinafter referred to as “operation frequency”) is controlled by the control unit 5. The Since the drive circuit 42a as described above can be realized by a well-known electronic circuit, detailed illustration and description thereof are omitted.

  One end of the induction coil 2 is connected to the output terminal on the low voltage side of the DC power supply 3 (that is, the circuit ground), and the other end is connected to the connection point of the switching elements Q1 and Q2 of the switching unit 42 via the resonance unit 41. Has been.

  The resonance unit 41 includes a series circuit of an inductor Ls and a series capacitor Cs connected between the connection point of the switching elements Q1 and Q2 of the switching unit 42 and the other end of the induction coil 2, and one end in series with the inductor Ls. A parallel capacitor Cp is connected to the connection point with the capacitor Cs and the other end is connected to the ground. That is, the inverter unit 4 is a so-called half-bridge type inverter circuit.

  Here, the operating frequency is controlled within a range higher than the resonance frequency f0 of the resonance circuit formed by the resonance unit 41 and the induction coil 2, as in the frequencies f1 and f2 shown in FIG. Therefore, as the operating frequency is lowered, the output power from the resonance unit 41 to the induction coil 2 (hereinafter simply referred to as “output power”) increases.

  When the dimming signal, which is an electrical signal instructing the light output of the electrodeless discharge lamp 1, is input from the outside and the light output instructed by the dimming signal is other than the maximum value, the control unit 5 is shown in FIG. As shown in FIGS. 4A and 4B and FIG. 4, a lighting period Ton having a lighting frequency f1 (for example, 135 kHz) that increases the output power to such an extent that the electrodeless discharge lamp 1 lights up, and the operating frequency. Is a frequency sufficiently high so that the extinguishing period Toff with the extinction frequency f2 (> f1, for example, 280 kHz) that reduces the output power to such an extent that the electrodeless discharge lamp 1 is extinguished cannot be recognized as blinking by human eyes. (Hereinafter referred to as “flashing frequency”), a dimming operation that is alternately repeated periodically is performed. The blinking frequency is set to 100 Hz or more, for example. In addition, when the light output instructed by the dimming signal is the maximum value, the control unit 5 performs a full lighting operation in which only the lighting period Ton is continued.

  Further, the light output instructed by the dimming signal has three or more stages, and the controller 5 turns on the lighting period Ton so that the light output of the electrodeless discharge lamp 1 is the light output instructed by the dimming signal. And the ratio of the length of the extinguishing period Toff. In the example of FIG. 1A, the light output is increased in two stages by increasing the light extinction period Toff by one period of output power during the light extinction period Toff (that is, by two zero cross points) as compared with the example of FIG. It is decreasing.

  Furthermore, the control unit 5 sets the timing of switching between the lighting period Ton and the extinguishing period Toff as the zero cross point of the output voltage from the resonance unit 41 to the induction coil 2 (that is, the voltage across the induction coil 2). Specifically, the control unit 5 counts the above-described zero cross points, and ends the lighting period Ton when the number of zero cross points counted after the start of the lighting period Ton reaches a predetermined number of times of lighting maintenance. Then, the extinguishing period Toff is started, and when the number of zero cross points counted after the extinguishing period Toff starts reaches a predetermined extinction maintaining number, the extinguishing period Toff is ended and the lighting period Ton is started. In the above operation, the duration of the lighting period Ton is directly proportional to the number of times that the lighting is maintained, and the duration of the lighting period Toff is directly proportional to the number of times that the lighting is maintained. As a method for the control unit 5 to detect the zero cross point, the zero cross point may be detected based on a detection voltage obtained by appropriately dividing or rectifying the voltage across the induction coil 2, or the switching unit 42. The timing at which the on / off switching of the switching elements Q1 and Q2 of the switching unit 42 is switched may be detected as a zero cross point based on an electrical signal input from the driving circuit 42a. With the above operation, the switching timing between the lighting period Ton and the extinguishing period Toff substantially coincides with the switching timing of the switching elements Q1 and Q2 of the switching unit 42 as shown in FIGS.

  Then, when the light output is newly instructed by the dimming signal, the control unit 5 sets the number of lighting maintenance times so that the light output of the electrodeless discharge lamp 1 matches the light output instructed by the dimming signal. Calculate the number of times the lamp is turned off. Here, in this embodiment, since the lighting frequency f1 is lower than the extinguishing frequency f2, that is, the interval between the zero cross points during the lighting period Ton is longer than the interval between the zero cross points during the extinguishing period Toff. Since the fluctuation range of the light output by increasing / decreasing the number of times is larger than the fluctuation range of the light output by increasing / decreasing the number of times of maintaining the light extinction once, the light output is roughly changed by changing the number of times the light is maintained to keep the light off The light output is finely adjusted by changing the number of times. That is, the controller 5 changes the number of times that the light is turned off within a predetermined adjustment range such that the overall fluctuation range of the light output is smaller than the fluctuation range of the light output corresponding to the number of times that the lighting is maintained. Then, when the light output is increased by one step from the state where the number of times that the extinction is maintained is other than the minimum value of the adjustment range, the light output is increased by decreasing the number of times that the extinction is maintained, and the number of times that the extinction is maintained is the minimum of the adjustment range When the light output is increased by one step from the value state, the number of times of maintaining the lighting is increased once, and the number of times of maintaining the extinction is set to the maximum value of the adjustment range. If the adjustment range is changed according to the number of times of lighting maintenance so that the adjustment range becomes wider as the number of times of lighting maintenance is smaller, the light output can be changed more finely than when the adjustment range is made constant. . Since the control unit 5 as described above can be realized by using, for example, a well-known integrated circuit called a microcomputer, detailed illustration and description thereof are omitted.

  According to the above configuration, compared to the case where the switching between the lighting period Ton and the lighting period Toff is performed at a point other than the zero cross point, the spike current at the time of switching between the lighting period Ton and the lighting period Toff is less likely to occur.

  In addition, since the light output is changed by changing both the number of times that the lighting is maintained and the number of times that the light is kept off, the light output can be changed more finely than when the light output is changed only by changing the number of times of lighting. In particular, for example, when the operating frequency f1 during the lighting period Ton is lowered to reduce the manufacturing cost, or when the blinking frequency is increased to suppress noise due to the action of the electromagnetic field of the induction coil 2, When the operating frequency f1 and the blinking frequency are close to each other, the number of zero cross points in each lighting period Ton is reduced, and the above effect becomes remarkable.

  Here, when the light output of the electrodeless discharge lamp 1 is decreased only by increasing the number of times of extinction maintenance (that is, extending the extinction period Toff) without changing the number of times of lighting maintenance, the extinction period Toff increases as the light output decreases. As a result, the plasma in the electrodeless discharge lamp 1 is reduced at the start of the lighting period Ton, and thus the power required for re-lighting is increased, resulting in an increase in electromagnetic noise and an increase in power consumption. On the other hand, in the present embodiment, the light output of the electrodeless discharge lamp 1 is also reduced by reducing the number of times that the lighting is maintained, so that it is possible to avoid the extinguishing period Toff being too long.

  In addition, as shown in FIG. 6, the control part 5 controls the drive circuit 42a so that each switching element Q1, Q2 of the switching part 42 may be maintained in the OFF state during the extinguishing period Toff, so that the resonance part 41 The output power to the induction coil 2 may be reduced to zero. In this case, since there is no restriction on the timing of switching from the turn-off period Toff to the turn-on period Ton, as shown in FIG. 7, the length (duration) of the turn-off period Toff is continuously changed, so The light output of the electric lamp 1 can be continuously changed.

  Alternatively, as shown in FIG. 8, a known DC power supply circuit capable of changing the output voltage is used as the DC power supply 3, and instead of the control unit 5 changing the length of the turn-off period Toff, the DC power supply as shown in FIG. 3, even if the light output of the electrodeless discharge lamp 1 is finely adjusted by changing the Vdc (hereinafter referred to as “DC output voltage”) Vdc. The light output can be continuously changed. More specifically, the DC power supply 3 in FIG. 8 includes a diode bridge DB that full-wave rectifies AC power input from an external AC power supply AC, an inductor L1 connected between the DC output terminals of the diode bridge DB, and a switching element. A series circuit of Q3, a series circuit of a diode D1 and an output capacitor C1 connected in parallel to the switching element Q3, and a chopper drive circuit 31 that periodically drives the switching element Q3 on and off. This is a known boost converter (boost chopper circuit) having both ends as output ends. The chopper drive circuit 31 detects the voltage across the output capacitor C1 (that is, the DC output voltage) Vdc, and the switching element Q3 is set so that the detected DC output voltage Vdc is a voltage instructed by the control unit 5. Feedback control of on-duty. In the example of FIG. 8, the dimming signal input from the outside is an on-duty rectangular wave corresponding to the instructed optical output, and is indicated by voltage division by resistors R1 and R2 and smoothing by capacitor C2. After being converted to a DC voltage having a voltage value corresponding to the optical output to be output, it is input to the control unit 5.

  The above-mentioned various electrodeless discharge lamp lighting devices can be held in the fixture main body 61 together with the electrodeless discharge lamp 1 as shown in FIGS. The lighting fixture 6 can be a street light as shown in FIG. 10 or a security light as shown in FIG. 11 by appropriately selecting the shape and structure of the fixture body 61. Since such various lighting fixtures 6 can be realized by well-known techniques, detailed illustration and description thereof will be omitted.

DESCRIPTION OF SYMBOLS 1 Electrodeless discharge lamp 2 Induction coil 3 DC power supply 5 Control part 6 Lighting fixture 41 Resonance part 42 Switching part 61 Appliance main body Ton lighting period Toff extinction period

Claims (4)

An induction coil disposed close to the electrodeless discharge lamp;
A resonating part that forms a resonant circuit with the induction coil;
Switching between the DC power supply and the resonance unit, which periodically switches the electrical connection between the DC power supply and the resonance unit, converts DC power input from the DC power supply to AC power and supplies it to the induction coil And
A control unit for controlling the switching unit,
The control unit includes a lighting period for controlling the switching unit so that the output power from the resonance unit to the induction coil is increased to the extent that the electrodeless discharge lamp is turned on, and the induction coil from the resonance unit to the extent that the electrodeless discharge lamp is turned off. A dimming operation in which the switching unit is controlled so as to reduce the output power to the dimming operation can be periodically repeated alternately, and the timing of switching from the lighting period to the extinguishing period in the dimming operation, An electrodeless discharge lamp lighting device, characterized in that a zero cross point of an output voltage from a resonance part to an induction coil is used.   The control unit continues the output of AC power from the resonance unit to the induction coil even during the extinguishing period of the dimming operation, and the timing of switching from the extinguishing period to the lighting period in the dimming operation is determined by the resonance unit. The electrodeless discharge lamp lighting device according to claim 1, wherein a zero-cross point of the output voltage from to the induction coil is set.   The control unit receives a dimming signal indicating the light output of the electrodeless discharge lamp from the outside, and the duration of the lighting period so that the light output of the electrodeless discharge lamp is the light output indicated by the dimming signal. The electrodeless discharge lamp lighting device according to claim 1 or 2, wherein the duration of the extinguishing period is determined by calculation.   A lighting fixture comprising: the electrodeless discharge lamp lighting device according to any one of claims 1 to 3; and a fixture main body that holds the electrodeless discharge lamp and the electrodeless discharge lamp lighting device, respectively.

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