JP4132347B2 - Discharge lamp lighting circuit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a discharge lamp lighting circuit for simultaneously lighting two discharge lamps such as fluorescent lamps.
[0002]
[Prior art]
Conventionally, a lighting circuit for simultaneously lighting a plurality of fluorescent lamps has been configured as shown in FIG. That is, as shown in FIG. 4A, a series connection of fluorescent lamps 13 and 14 is connected between both ends of the secondary winding 12 of the drive transformer 11. That is, one end of one heater 15 of the fluorescent lamp 13 is connected to one end of the secondary winding 12, the other end is connected to one end of the other heater 17 of the fluorescent lamp 13 through the starting capacitor 16, and the other end of the heater 17 is connected. Is connected to one end of one heater 18 of the fluorescent lamp 14, the other end of the heater 18 is connected to one end of the other heater 21 of the fluorescent lamp 14 through a starting capacitor 19, and the other end of the heater 21 is the secondary winding. 12 is connected to the other end. Thus, the fluorescent lamps 13 and 14 are lighted simultaneously by applying alternating current power between the both ends of the fluorescent lamps 13 and 14 connected in series.
[0003]
Alternatively, as shown in FIG. 4B, one end of each heater 15, 18 of the fluorescent lamps 13, 14 is connected to one end of the secondary winding 12, and each end of each other heater 17, 21 is connected to the secondary winding. The other end of the wire 12 is connected, the heaters 15 and 18 are connected to the heater winding 22 of the drive transformer 11, the heaters 17 and 21 are connected to the heater winding 23, and the fluorescent lamps 13 and 14 are connected to the transformer 11. Connected in parallel, the fluorescent lamps 13 and 14 are turned on simultaneously.
[0004]
[Problems to be solved by the invention]
In the series lighting system shown in FIG. 4A, when one of the fluorescent lamps 13 and 14 is cut off, that is, cannot be lit, current does not flow to the other fluorescent lamp and the lamp is extinguished. Moreover, even if it tries to light, alternating current power is not applied to a normal fluorescent lamp by the cut-off fluorescent lamp, and it cannot light.
[0005]
In the parallel lighting system shown in FIG. 4B, at the start of lighting, generally, one of the two fluorescent lamps 13 and 14 is turned on first, the voltage between both ends thereof becomes a small value, and the other fluorescent lamp cannot be turned on. There was a case. Even if both fluorescent lamps 13 and 14 are turned on, if one of the fluorescent lamps is cut off, two currents flow through the remaining fluorescent lamps, resulting in unstable lighting, and an inverter that supplies AC power to the drive transformer 11 There was a case where it was damaged.
[0006]
It is an object of the present invention to reliably turn on two discharge lamps and to turn on the other discharge lamp even when one of the discharge lamps is cut off, or to maintain lighting stably. It is to provide a discharge lamp lighting circuit.
[0007]
[Means for Solving the Problems]
According to the present invention, the differential winding choke coil is interposed between at least one end of the secondary winding of the drive transformer and each end of the plurality of discharge lamps.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an embodiment of the present invention. In this embodiment, a push-pull automatic oscillation circuit 31 is configured to supply AC power to the drive transformer 11. That is, the emitters of the switching transistors 32 and 33 are connected to each other and connected to one terminal 34 of the DC power supply, and the collectors of the transistors 32 and 33 are both ends of the capacitor 35 and the primary winding 36 of the drive transformer 11. Connected to both ends, the middle point of the primary winding 36 is connected to the other power supply terminal 39 of the DC power source through the choke coil 37 and the reverse connection protection diode 38, and the feedback winding 41 coupled to the primary winding 36. Both ends are connected to the bases of the transistors 32 and 33. Both ends of the power supply winding 61 coupled to the secondary winding 36 are connected to both ends of the capacitor 63 through the rectifying diode 62, and both ends of the capacitor 63 are connected to both ends of the Zener diode 65 through the resistance element 64. Are connected to the bases and emitters of the transistors 32 and 33 through resistance elements.
[0009]
Oscillation AC power from the oscillation circuit 31 is supplied to the secondary winding 12. A leakage transformer is used as the drive transformer 11.
One end of the secondary winding 12 is connected to one end of each of the fluorescent lamps 13 and 14, and the other end is connected to one end of both coils 43 a and 43 b on the same side of the differential winding choke coil 43. The other ends of the coils 43a and 43b of 43 are connected to the other ends of the fluorescent lamps 13 and 14, respectively. In the differential winding choke coil 43, the windings of the coils 43a and 43b are the same and the winding direction is reversed, or the winding direction is the same and a current is passed in the opposite direction, so that the magnetic fluxes of the windings cancel each other. To be fit. The heaters 15 and 18 of the fluorescent lamps 13 and 14 on the side to which the differential winding choke coil 43 is connected are connected to both ends of the heater windings 44 and 45 of the transformer 11, respectively. The heaters 17 and 21 are connected in common to both ends of the heater winding 46 of the transformer 11.
[0010]
In this configuration, the oscillation circuit 31 starts to oscillate, and a voltage V is induced in the secondary winding 12. At this moment, no current flows through the differential winding choke coil 43, and the operation as a choke coil is not performed. A voltage V is applied across the lamps 13 and 14. As a result, when one of the fluorescent lamps 13 is turned on first, most of the limiting current based on the leakage transformer tends to flow to the fluorescent lamp 13. Along with this, a current flows through the differential winding choke coil 43, and this current causes an operation as a choke coil, and a voltage v that restricts the current flowing through the fluorescent lamp 13 is generated in the coil 43a. The polarity is opposite to the induced voltage V of the secondary winding 12. A voltage v ′ = v having the same polarity as the voltage V of the secondary winding 12 is generated in the coil 43 b connected to the fluorescent lamp 14 by the transformer action of the differential winding choke coil 43. Therefore, the voltage V + v ′ is applied to the unlit fluorescent lamp 14, and the fluorescent lamp 14 is also lit.
[0011]
In this way, both the fluorescent lamps 13 and 14 are lit. In a state where both the fluorescent lamps 13 and 14 are lit, the current i that is the sum of the currents i ₁ and i ₂ flowing through the fluorescent lamps 13 and 14 is limited to the current i determined by the current limiting action (constant current action) of the transformer 11. Is done. When one of the fluorescent lamps 14 is turned off while both the fluorescent lamps 13 and 14 are lit, the current i limited to the transformer tends to flow to the other fluorescent lamp 13, that is, 2 to one fluorescent lamp 13. A current corresponding to the current flows, but the current is reduced by the choke action of the differential winding choke coil 43, and a current smaller than i flows through the fluorescent lamp 13. The choke coil 43 may be selected so that the current flowing at this time is equal to the current flowing in one fluorescent lamp when normal. Thus, even if one of them breaks, overcurrent flows through one fluorescent lamp and there is no risk of damage.
[0012]
As described above, the differential winding choke coil 43 can be used to turn on the two fluorescent lamps 13 and 14 simultaneously, and even if one of the fluorescent lamps is cut off, it can be operated normally. By using the differential winding choke coil in this way, more fluorescent lamps can be turned on. An example of lighting four fluorescent lamps is shown in FIG.
That is, as shown in FIG. 2A, the same number is assigned to the portion corresponding to FIG. 1, and the end of the secondary winding 12 on the side where the differential winding choke coil 43 is connected is interposed via the differential winding choke coil 51. The other ends of the secondary winding 12 are connected to the connection points of the fluorescent lamps 13 and 14 and the connection points of the fluorescent lamps 52 and 53 through the differential winding choke coil 54, respectively. The You may make it show in FIG. 2B. That is, one end of the secondary winding 12 is connected to one end of the differential winding choke coils 43 and 51 through the differential winding choke coil 54, and the other ends of the differential winding choke coils 43 and 51 are connected to the fluorescent lamps 13 and 14. One end of each of the fluorescent lamps 13, 14, 52, 53 is connected to the other end of the secondary winding 12.
[0013]
Alternatively, as shown in FIG. 3, one end of the fluorescent lamps 13 and 53 is connected to each other, one end of the fluorescent lamps 14 and 52 is connected to each other, and the other end of the fluorescent lamps 13 and 14 is connected to each other. Are connected to each other, and one end of each of the two windings of the differential winding choke coil 55 is connected to a connection point between the fluorescent lamps 13 and 53 and a connection point between the fluorescent lamps 14 and 52. The other ends of the two windings are connected to one end of the secondary winding 12. One end of each of the two windings of the differential winding choke coil 56 is connected to the connection point of the fluorescent lamps 13 and 14 and the connection point of the fluorescent lamps 52 and 53, and each other end of the two windings of the choke coil 56 is 2 Connected to the other end of the next winding 12. According to this configuration, the number of choke coils can be reduced as compared with the case shown in FIGS.
[0014]
As can be understood from the embodiments of FIGS. 1, 2, and 3, by inserting a differential winding choke coil between a plurality of fluorescent lamps that are lit in parallel and the secondary winding 12, a plurality of The fluorescent lamp can be reliably turned on, and even if one or more of the plurality of lit fluorescent lamps are cut off, the other fluorescent lamps are not affected and the lighting state is stably maintained.
[0015]
Many fluorescent lamps can be simultaneously turned on by these methods.
[0016]
【The invention's effect】
As described above, according to the present invention, it is possible to reliably turn on a plurality of discharge lamps with one oscillation circuit and one drive transformer, and even if one of the plurality of discharge lamps being turned off is cut off, The lighting state can be stably maintained without being affected by other discharge lamps. Therefore, the circuit can be simplified and the number of assembly steps can be reduced, and the apparatus can be reduced in size and cost.
[Brief description of the drawings]
FIG. 1 is a connection diagram showing an embodiment of the present invention.
FIG. 2 is a view showing a main part of another embodiment of the present invention.
FIG. 3 is a view showing a main part of still another embodiment of the present invention.
FIG. 4 is a diagram showing a conventional lighting circuit.

Claims (1)

In a discharge lamp lighting circuit for lighting a plurality of discharge lamps in parallel by AC power through a driving transformer,
One end of the secondary winding of the drive transformer is connected to one end on the same side of the differential winding choke coil, and the other end of the differential winding choke coil is connected to one end of each of the two discharge lamps. One end of the other two discharge lamps is connected to each connection point between the two discharge lamps and the differential winding choke coil, and the differential winding choke coil is connected to one end of the secondary winding and the above Interposed between one end of each of the two discharge lamps and the other two discharge lamps,
One winding of a second differential winding choke coil is interposed between the other end of the secondary winding and each other end of the two discharge lamps, and the second differential winding choke coil The other winding is interposed between the other ends of the other two discharge lamps and the other end of the secondary winding .

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