JP3938593B2 - Lamp lighting device - Google Patents

Description

  The present invention relates to a lamp lighting device.

  An example of a conventional discharge tube lighting device is shown in FIG. In the discharge tube lighting device of FIG. 1, a voltage V1 is applied to the primary winding of the main transformer T100 by an inverter including a switching circuit, and a voltage VMT is generated on the secondary winding side of the main transformer T100. One end of the secondary winding of the main transformer T100 is connected to one end of the primary winding and the secondary winding of the shunt transformer (balancer) TB100, and the other end of the secondary winding of the main transformer T100 is grounded. One end of a discharge tube Lp100 such as a cold cathode tube is connected to the other end of the primary winding of the shunt transformer TB100, and one end of a discharge tube Lp102 is connected to the other end of the secondary winding of the shunt transformer TB100. Has been. The shunt transformer TB100 is provided with a primary winding and a secondary coil for the purpose of suppressing variations in the current flowing through the discharge tubes due to variations in the characteristics of the discharge tubes and avoiding the occurrence of discharge tubes that are not lit due to differences in the starting characteristics of the respective discharge tubes. The voltage is generated by the current difference of the secondary winding, and is used so that a reverse polarity voltage is generated on the primary winding side and the secondary winding side. The other ends of the discharge tubes Lp100 and Lp102 are connected to one end of a resistor R100, and the other end of the resistor R100 is grounded.

  In the prior art, in such a discharge tube lighting device, the secondary winding of the main transformer T100 and the primary winding and secondary winding of the shunt transformer TB100 are discharged together with the overvoltage limiting circuit 101 for preventing overvoltage. A constant current control circuit 102 for equalizing the current flowing through the tubes Lp100 and Lp102 is used. For this reason, the voltage at the connection point between the resistor R100 and the discharge tubes Lp100 and Lp102 is input to the constant current control circuit 102, and the voltage VMT of the secondary winding of the main transformer T100 and the terminal of the primary winding of the shunt transformer TB100. The output of the detection circuit 103 that detects the voltage and the output of the detection circuit 104 that detects the voltage across the secondary winding of the shunt transformer TB100 are input to the overvoltage limiting circuit 101. The switching of the inverter switching circuit is controlled by the output of the overvoltage limiting circuit 101.

Since a high voltage is required when starting the discharge tube, a high voltage is generated in the shunt transformer TB100 and the main transformer T100. Further, if an abnormality occurs in a certain discharge tube during operation and a circuit becomes open, a high voltage is generated in the shunt transformer TB100 and the main transformer T100. In order to prevent breakdown of the shunt transformer TB100 and the main transformer T100, the overvoltage limiting circuit 101 or the protection circuit and the voltage clamp circuit are provided as described above to limit the maximum voltage of the shunt transformer TB100 and the main transformer T100. It was. In that case, there were the following problems, and there were problems in terms of shape and cost.
(1) Two protection circuits are required. (One system is the overvoltage limiting circuit 101 for the main transformer T100, and the other system is the detection circuits 103 and 104 and the overvoltage limiting circuit 101 for the shunt transformer TB100.)
(2) The voltage generated at the connection between the shunt transformer TB100 and the discharge tube becomes higher than necessary, and the wiring pattern interval, component rating, etc. need to be increased more than necessary.

  More specifically, the maximum value VLAMPmax of the voltage VLAMP generated at the connection between the shunt transformer TB100 and the discharge tube is equal to the maximum value VMTmax of the voltage VMT generated at the secondary winding of the main transformer T100 and the shunt transformer TB100. Is the sum of the maximum value VBmax of the voltage VB generated at the same time. That is, VLAMPmax = VMTmax + VBmax. In addition, VLAMP needs to secure a voltage VLAMPSTRIKE necessary for lighting the discharge tube. On the other hand, since the voltage VB depends on the variation of each discharge tube and the characteristics of the shunt transformer TB100, the VMT needs to be able to generate VLAMPSTRIKE. As a result, there is a possibility that VLAMPmax = VLAMPSTRIKE + VBmax, and wiring pattern intervals and component ratings that can withstand this voltage are required.

  A circuit similar to the circuit shown in FIG. 1 is also disclosed in US Application Publication No. 2004-0155596A1.

Further, in US Application Publication No. 2005-93471A1 and US Application Publication No. 2005-93472A1, a ring balancer that has a plurality of balancing transformers and performs current sharing in a backlight system composed of a plurality of lamps is disclosed. It is disclosed. The primary windings of the balancing transformer in this ring balancer are each connected in series to one specific lamp, and all secondary windings are connected to form a closed loop. As a result, the current on the secondary winding side is shared by the closed loop of the secondary winding, so that the lamp driving current on the primary winding side is also shared.
US Application Publication No. 2004-0155596A1 US Application Publication No. 2005-93471A1 US Application Publication No. 2005-93472 A1

  As described above, the conventional technique has a problem in terms of cost and the like for the reason described above.

  Accordingly, an object of the present invention is to provide a technique for reducing costs in a lighting device for a lamp such as a discharge tube.

  Another object of the present invention is to provide a technique for improving safety in a lamp lighting device.

  Furthermore, the other object of this invention is to provide the technique for lighting a lamp | ramp efficiently and reliably in a lamp lighting device.

  Furthermore, another object of the present invention is to provide a novel technique for making the lamp brightness uniform in a lamp lighting device.

  A lamp lighting device according to a first aspect of the present invention includes an inverter transformer, a switching circuit that is connected to a primary winding of the inverter transformer and performs switching for converting a voltage from an input power source, and a secondary of the inverter transformer. Switching circuit switching based on a balancer connected to the windings to equalize the current flowing through the lamps and a voltage corresponding to the sum of the voltage generated at the secondary winding of the inverter transformer and the voltage generated at the balancer And a control circuit for generating a control signal for controlling.

  Thus, by performing control based on the voltage according to the sum of the voltage generated in the secondary winding of the inverter transformer and the voltage generated in the balancer, a voltage higher than necessary is not applied to the component, and the wiring pattern and This is advantageous in terms of component costs.

  Also, the balancer described above is connected in series between the secondary winding of the inverter transformer and the lamp, and the control circuit described above switches the switching circuit based on the potential at the connection point between the balancer and the lamp. You may make it generate | occur | produce the control signal which controls. Thus, without detecting and controlling the voltage applied to the secondary winding of the inverter transformer (main transformer) directly, the voltage at the connection point between the balancer and the lamp is detected and controlled. Can be reduced. In addition, only with such control, the inverter transformer and the balancer can be operated with no problem, and the lamp can be reliably turned on.

  Further, the balancer described above is provided for each lamp, and includes a first detection circuit that detects a voltage corresponding to a voltage generated in the secondary winding of the inverter transformer, and a voltage generated in a portion in charge of each lamp in the balancer. A second detection circuit that detects a voltage corresponding to the maximum voltage, and a circuit that adds the output voltage of the first detection circuit and the output voltage of the second detection circuit may be further included. For example, a case where the voltage at the connection point between the balancer and the lamp cannot be directly detected is dealt with.

  Further, the balancer described above has a plurality of transformers, and the primary winding of each transformer is connected in series to one lamp in charge and the secondary winding of the inverter transformer, and the secondary winding of the transformer May be connected to form a closed loop with the secondary winding of another transformer. Further, the plurality of transformers described above may have a tertiary winding in which a voltage corresponding to the voltage generated in the primary winding is generated.

  A lamp lighting device according to a second aspect of the present invention includes an inverter transformer, a switching circuit that is connected to a primary winding of the inverter transformer and performs switching for converting a voltage from an input power source, and a secondary of the inverter transformer. A balancer connected to the windings for equalizing the current flowing through the plurality of lamps and a control circuit for generating a control signal for controlling the switching of the switching circuit based on the voltage generated in the balancer, as described above The balancer includes a transformer having a tertiary winding, and a voltage generated in the balancer is detected from the tertiary winding. In this way, even when a voltage dividing capacitor cannot be arranged for reasons such as avoiding discharge, the voltage corresponding to the primary winding can be detected and the lamp lighting device can be controlled based on the detected voltage. become.

  A lamp lighting device according to a third aspect of the present invention includes an inverter transformer, a switching circuit that is connected to a primary winding of the inverter transformer and performs switching for converting a voltage from an input power source, and a secondary of the inverter transformer. A balancer connected to the winding for equalizing the current flowing through the plurality of lamps, and a maximum voltage and a current flowing through the lamps among the voltages corresponding to the voltages detected through the balancer and applied to the plurality of lamps. And a control circuit that detects that all of the lamps are turned on, generates a control signal for ending an activation mode that operates under conditions different from normal operation, and outputs the control signal to the switching circuit. The start-up mode operated under conditions different from the normal operation is a mode that operates at a resonance frequency of a resonance circuit formed on the secondary winding side of the inverter transformer, for example. In this way, it is possible to appropriately determine the end of the startup mode.

  In addition, the control circuit described above has the maximum voltage among the voltages at the connection point between the lamp and the portion in charge of each lamp as the maximum voltage among the voltages applied to the plurality of lamps. A circuit may be included that detects that the total current flowing through all the lamps is equal to or higher than a predetermined level.

Further, the balancer described above has a plurality of transformers, and the primary winding of each transformer is connected in series to one lamp in charge and the secondary winding of the inverter transformer, and the secondary winding of the transformer However, the secondary windings of other transformers may be connected to form a closed loop.

The lamp lighting device according to the fourth aspect of the present invention includes one or a plurality of inverter transformers and a first transformer, and the primary winding of the first transformer is a secondary winding of the one or more inverter transformers. And a first balancer connected to one end of a specific lamp among the plurality of lamps for equalizing the current flowing through the plurality of lamps and a second transformer, and a primary winding of the second transformer Is connected to the other end of the specific lamp among the secondary winding of one or a plurality of inverter transformers and a plurality of lamps, and a second balancer for equalizing the current flowing through the plurality of lamps, and a plurality of lamps Means for supplying voltages having opposite phases to each other. And the location where the secondary winding of the 1st transformer and the secondary winding of the 2nd transformer were connected in series exists . As described above, the currents flowing at both ends of the lamp are made uniform by the first balancer and the second balancer, and the brightness of the plurality of lamps can be made uniform.

  Also, a plurality of first transformers and second transformers are provided, and the first transformers are connected in series with secondary windings having different polarities, and the second transformers have secondary windings having different polarities. The secondary winding of at least one first transformer and the secondary winding of at least one second transformer may be connected in series in the same polarity relationship.

Further, the first balancer described above has a plurality of first transformers, and the primary winding of each first transformer includes one lamp in charge and secondary windings of one or more inverter transformers. And the secondary winding of the first transformer is connected to a terminal of a different polarity of the secondary winding of any other first transformer in the first balancer. Good. The second balancer has a plurality of second transformers, and the primary winding of each second transformer is connected in series to one lamp in charge and the secondary winding of one or more inverter transformers. Then, the secondary winding of the second transformer may be connected to a terminal having a different polarity of the secondary winding of any other second transformer in the second balancer. The secondary winding of the transformer in the first balancer and the secondary winding of the transformer in the second balancer may be connected to form a closed loop.

  The lamp lighting device according to the fifth aspect of the present invention is connected to the primary winding of the first inverter transformer and the first inverter transformer, and performs switching for converting the voltage from the first input power supply. A first switching circuit, a first balancer connected to one end of each of the secondary winding and the plurality of lamps of the first inverter transformer, and for equalizing the current flowing through the plurality of lamps; The first inverter transformer is connected to the primary winding of the second inverter transformer, and the second inverter transformer performs switching for converting the voltage from the second input power source so as to be in the opposite phase to the output of the first inverter transformer. 2 switching circuit, the secondary winding of the second inverter transformer and the other end of each of the plurality of lamps, for equalizing the current flowing through the plurality of lamps Switching of the first switching circuit and the second switching circuit when a change in the current flowing through the lamp is detected by the detection circuit over a predetermined level. And a control circuit for performing current limiting. The first balancer and the second balancer are connected.

  The fact that the current flowing to the lamp has changed more than the specified level means that a problem has occurred in one of the lamps or a problem has occurred in the inverter transformer, so safety is ensured by stopping the operation or limiting the current. To do.

  It is possible to arbitrarily combine the lamp lighting circuit technologies according to the first to fifth aspects described above.

  There are a plurality of circuits for realizing the above configuration, and specific examples are shown below, but the present invention is not limited to these.

  According to the present invention, it is possible to reduce costs in a lamp lighting device such as a discharge tube.

  Further, as another aspect of the present invention, safety can be improved in the lamp lighting device.

  Furthermore, as another aspect of the present invention, the lamp lighting device can efficiently and reliably light the lamp.

Furthermore, another object of the present invention will cormorants it can be made uniform the brightness of the lamp in the lamp lighting device.

A. First Embodiment FIG. 2 shows a circuit example of a lamp lighting device according to a first embodiment. The lamp lighting device according to the first embodiment includes an inverter including a switching circuit, an inverter transformer (main transformer) T1, a shunt transformer (balancer) TB1, lamps Lp1 and Lp2 such as cold cathode tubes, and resistors. R1, voltage dividing and rectifying circuits 10 and 11, rectifying circuit 12, overvoltage limiting circuit 13, constant current control circuit 14, and diodes 15 and 16 are included. The overvoltage limiting circuit 13 includes a comparator 131, a first reference voltage power supply 132, and a MOSFET S1. The constant current control circuit 14 includes comparators 141 and 144, a second reference voltage power supply 142, and a triangular wave generator 143.

  The inverter is connected to the primary winding of the inverter transformer T1, and the voltage V1 is applied to the primary winding of the inverter transformer T1. A voltage VMT is generated on the secondary winding side of the inverter transformer T1. One end of the secondary winding of the inverter transformer T1 is connected to one end of the primary winding and the secondary winding of the shunt transformer TB1. The other end of the secondary winding of the inverter transformer T1 is grounded. The other end of the primary winding of the shunt transformer TB1 is connected to one end of the lamp Lp1, and the other end of the secondary winding of the shunt transformer TB1 is connected to one end of the lamp Lp2. The other end of the lamp Lp1 and the other end of the lamp Lp2 are connected to one end of the resistor R1, and the other end of the resistor R1 is grounded. The voltage on the primary winding side of the shunt transformer TB1 is VB1, and the voltage on the secondary winding side is VB2. The shunt transformer TB1 is used so that the primary winding and the secondary winding have opposite polarities.

  The connection point between the primary winding of the shunt transformer TB1 and the lamp Lp1 is connected to the voltage dividing and rectifying circuit 10, and the voltage dividing and rectifying circuit 10 is connected to the overvoltage limiting circuit 13 via the diode 15. Yes. The connection point between the secondary winding of the shunt transformer TB1 and the lamp Lp2 is connected to the voltage dividing and rectifying circuit 11, and the voltage dividing and rectifying circuit 11 is connected to the overvoltage limiting circuit 13 via the diode 16. . A connection point between the lamps Lp1 and Lp2 and the resistor R1 is connected to the rectifier circuit 12, and the rectifier circuit 12 is connected to the constant current control circuit.

  In the overvoltage limiting circuit 13, the output of the voltage divider and rectifier circuit 10 and the voltage divider and rectifier circuit 11 are input to the positive input terminal of the comparator 131 via the diode 15 or 16. The positive terminal of the reference voltage power supply 132 is connected to the negative input terminal of the comparator 131, and the negative terminal of the reference voltage power supply 132 is grounded. The output of the comparator 131 is connected to the gate of the MOSFET S1. The source of the MOSFET S 1 is grounded, and the drain is connected to the negative input terminal of the comparator 144 in the constant current control circuit 14. The output of the rectifier circuit 12 is connected to the negative input terminal of the comparator 141 in the constant current control circuit 14. The positive input terminal of the reference voltage power supply 142 is connected to the positive input terminal of the comparator 141. Yes. The negative terminal of the reference voltage power supply 142 is grounded. The output of the comparator 141 is connected to the negative input terminal of the comparator 144. A triangular wave generator 143 is connected to the positive input terminal of the comparator 144. The output of the comparator 144 is input to the inverter, and the duty ratio of the switching circuit included in the inverter is changed.

  The operation of the lamp lighting device shown in FIG. 2 will be briefly described. The voltage V1 applied to the primary winding of the inverter transformer T1 by the output of the inverter becomes VMT on the secondary winding side, and is stepped up or down by the shunt transformer TB1 and applied to the lamps Lp1 and Lp2. The operation of the shunt transformer is the same as before, and the primary winding is used for the purpose of suppressing variations in the current flowing through the lamp due to variations in lamp characteristics and avoiding the occurrence of lamps that do not turn on due to differences in the starting characteristics of each lamp. And a voltage is generated by the current difference between the secondary windings. More specifically, as shown in FIG. 3, when the lamp Lp1 is not lit and the lamp Lp2 is lit, a voltage VLamp1 = VMT + VB1 higher than the voltage VMT is applied to the lamp Lp1 by the shunt transformer TB1. Then, a voltage VLamp2 = VMT + VB2 (here, VB2 has a negative value) lower than the voltage VMT is applied to the lamp Lp2. In the example of FIG. 2, since there are only two lamps, VB1 + VB2 = 0. In the example of FIG. 2, VOVP = VMT + VB1 = VMT-VB2.

  The overvoltage limiting circuit 13 compares the higher of the voltages at the connection point between the shunt transformer TB1 and the lamp Lp1 or Lp2 with the output voltage (control target voltage) of the reference voltage power supply 132, and determines the voltage at the connection point. When the higher one is equal to or higher than the output voltage of the reference voltage power supply 132, the output of the MOSFET S1 is turned on, and the negative input terminal of the comparator 131 in the overvoltage limiting circuit 13 is connected to the ground. On the other hand, when the higher one of the voltages at the connection point is lower than the output voltage of the reference voltage power supply 132, the output of the MOSFET S1 is turned off, and the output of the comparator 131 in the overvoltage limiting circuit 13 remains unchanged. Output to the negative input terminal. In the constant current control circuit 14, the current flowing through the lamps Lp 1 and Lp 2 is extracted by the resistor R 1 and input to the comparator 141, and the comparator 141 compares it with the output voltage of the reference voltage power supply 142. If the current flowing through the lamps Lp1 and Lp2 is less than the reference, the output of the comparator 141 is increased, and a control signal is generated so that the on-duty becomes longer in comparison with the triangular wave in the comparator 144. That is, the voltage at the connection point between the shunt transformer TB1 and the lamp Lp1 or Lp2 is controlled to a predetermined voltage (VOVP. VO) while controlling the current flowing through the lamp to be constant by the overvoltage limiting circuit 13 and the constant current control circuit 14. More specifically, the control is performed so that the maximum value VLAMPSTRIKE or VLAMPSTRIKE of the lighting voltage is equal to or less than a voltage obtained by adding a necessary margin.

Here, the details of FIGS. 2 and 3 are as follows. That is,
VMT + VBmax ≦ VOVP (1)
(VBmax is the maximum voltage (positive value) among the voltages applied to the shunt transformer)
VMT + VBmin = VLAMPONmin (2)
(VLAMPONmin is the minimum value of the drive voltage when there are a plurality of lit lamps. VBmin is the lowest voltage (negative value) among the voltages applied to the shunt transformer)
VB1 + VB2 = 0 (3)

From equation (1)
VMT ≦ VOVP−VBmax (1) ′
From equation (3), VBmax> 0 (or all VB = 0 can only be),
VMT ≦ VOVP (4)
Therefore, there is no problem if the inverter transformer T1 has a breakdown voltage equal to or higher than VOVP.

Also, from equation (2)
VMT = VLAMPONmin−VBmin (2) ′
Since VBmin <0 from equation (3),
VMT> VLAMPONmin (5)
When VMT falls below this level, all lamps are turned off.

Furthermore, from equation (1)
VBmax ≦ VOVP−VMT (1) ”
From equation (5), VBmax ≦ VOVP−VLAMPONmin (6)

Also, from equation (2)
VBmin = VLAMPONmin-VMT
Taking the absolute value of both sides,
| VBmin | = VMT−VLAMPONmin (2) ”
From equation (4)
｜ VBmin | ≦ VOVP−VLAMPONmin (7)

  From the equations (6) and (7), there is no problem if the shunt transformer TB1 has a withstand voltage equal to or higher than VOVP-VLAMPONmin.

  Here, if the maximum value of the lamp lighting voltage is VLAMPSTRIKE, the values are summarized as shown in FIG. That is, conventionally, the maximum value of the voltage VMT generated on the secondary winding side of the inverter transformer T1 is VLAMPSTRIKE, the maximum value of the voltage applied to the shunt transformer TB1 is VBmax, and the shunt transformer TB1 and the lamp The maximum value of the voltage at the connection point is VLAMPSTRIKE + VBmax. However, according to the present embodiment, the maximum value of the voltage VMT generated on the secondary winding side of the inverter transformer T1 is VLAMPSTRIKE, and the shunt transformer TB1 The maximum value of the voltage is VLAMPSTRIKE−VLAMPONmin, and the maximum value of the voltage at the connection point between the shunt transformer TB1 and the lamp is VLAMPSTRIKE. Therefore, the voltage at the connection point between the shunt transformer TB1 and the lamp is lower than the conventional one, and the withstand voltage can be lowered. Therefore, an inexpensive transformer can be used, and further, there is a safety problem such as discharge from the wiring pattern of the board. Can also be reduced. That is, it is advantageous to route the wiring pattern. In the example described above, one shunt transformer is used and two lamps are used. However, the present invention can also be applied to a case where a plurality of lamps are lit by a plurality of shunt transformers. For example, when N lamps are turned on by N shunt transformers, VB1 + VB2 +. . . The expression is expanded as + VBN = 0, but substantially the same as above.

  Thus, in the present embodiment, the voltage VMT + VBmax is detected at the connection point between the shunt transformer TB1 and the lamp Lp1 or Lp2. The voltage VMT + VBmax at the connection point is controlled to be equal to or lower than a predetermined voltage (specifically, a maximum value VLAMPSTRIKE or a voltage obtained by adding a necessary margin from VLAMPSTRIKE). By doing this, the control is simplified and the breakdown voltage of the transformer can be lowered.

B. Second Embodiment FIG. 5 shows a circuit example of a lamp lighting device according to a second embodiment. The lamp lighting device according to the second embodiment is a modification of the lamp lighting device according to the first embodiment, and a balancer 17 portion in FIG. 5 is a portion different from the first embodiment. The balancer 17 includes transformers TB1a and TB1b. The transformers TB1a and TB1b are transformers that generate a voltage in phase with the voltage of the primary winding on the secondary winding side. The first terminal of the primary winding of the transformer TB1a is connected to the first terminal of the secondary winding of the inverter transformer T1, and the second terminal of the primary winding of the transformer TB1a is the first terminal of the lamp Lp1. And is connected to the input terminal of the voltage dividing and rectifying circuit 10. Similarly, the first terminal of the primary winding of the transformer TB1b is connected to the first terminal of the secondary winding of the inverter transformer T1, and the second terminal of the primary winding of the transformer TB1b is the first terminal of the lamp Lp2. The terminal and the voltage divider and the input terminal of the rectifier circuit 11 are connected. The first terminal of the secondary winding of the transformer TB1a is connected to the second terminal of the secondary winding of the transformer TB1b, and the first terminal of the secondary winding of the transformer TB1b is the secondary winding of the transformer TB1a. Connected to the second terminal of the wire. That is, the secondary windings of the transformers TB1a and TB1b form a closed loop by connecting terminals having different polarities. In this way, since the currents flowing through the secondary windings of the transformers TB1a and TB1b are the same, the drive currents of the lamps Lp1 and Lp2 flowing through the primary windings of the transformers TB1a and TB1b are also the same. That is, the brightness of the lamps Lp1 and Lp2 is made uniform.

  Note that the configuration and operation of the parts other than the balancer 17 are the same as those in the first embodiment, and a description thereof will be omitted.

C. Third Embodiment FIG. 6 shows a circuit example of a lamp lighting device according to a third embodiment. The lamp lighting device according to the third embodiment is a modification of the lamp lighting device according to the first and second embodiments. In the present embodiment, a transformer TB1c provided for detecting a voltage in which the primary winding is connected to the lamp, the secondary winding forms a closed loop, and the tertiary winding is generated in the primary winding; TB1d, diodes 20a and 20b connected to the tertiary windings of transformers TB1c and TB1d, a voltage dividing and rectifying circuit 18, and a voltage adding circuit 19 are connected to the current divider transformer TB1 in FIG. 2 or the balancer 17 in FIG. Instead of the voltage dividing and rectifying circuits 10 and 11 and the diodes 15 and 16, they are provided. The transformer TB1c and the transformer TB1d generate a voltage in phase with the voltage of the primary winding in the secondary winding and the tertiary winding.

  The first terminal of the primary winding of the transformer TB1c is connected to the first terminal of the secondary winding of the transformer T1, and the second terminal of the primary winding of the transformer TB1c is connected to the first terminal of the lamp Lp1. It is connected. The first terminal of the primary winding of the transformer TB1d is connected to the first terminal of the secondary winding of the transformer T1, and the second terminal of the primary winding of the transformer TB1d is the first terminal of the lamp Lp2. Connected to the terminal. The first terminal of the secondary winding of the transformer TB1c is connected to the second terminal of the secondary winding of the transformer TB1d, and the first terminal of the secondary winding of the transformer TB1d is the secondary winding of the transformer TB1c. Connected to the second terminal of the wire. That is, the secondary windings of the transformers TB1c and TB1d form a closed loop by connecting terminals having different polarities. In this way, since the currents flowing through the secondary windings of the transformers TB1c and TB1d are the same, the drive currents of the lamps Lp1 and Lp2 flowing through the primary windings of the transformers TB1c and TB1d are also the same. That is, the brightness of the lamps Lp1 and Lp2 is made uniform. This part is the same as in the second embodiment.

  On the other hand, the input terminal of the voltage dividing and rectifying circuit 18 is connected to the first terminal of the secondary winding of the transformer T1. A voltage corresponding to VMT is detected by the voltage dividing and rectifying circuit 18. The first terminal of the tertiary winding of the transformer TB1c is connected to the anode of the diode 20a, and the second terminal is grounded. Similarly, the first terminal of the tertiary winding of the transformer TB1d is connected to the anode of the diode 20b, and the second terminal is grounded. The cathodes of the diodes 20 a and 20 b are connected and further connected to the input terminal of the voltage adding circuit 19. A voltage corresponding to the maximum voltage VBmax appears at the input terminal of the voltage adding circuit 19 among the voltage VB1 on the primary winding side of the transformer TB1c and the voltage VB2 on the primary winding side of the transformer TB1d. In particular, when the primary winding side of the transformer TB1c or TB1d is short-circuited or an abnormality occurs in the lamp Lp1 or Lp2, etc., a large value of voltage appears when the current balance on the primary winding side of the transformer TB1c or TB1d is lost. To do. Therefore, the voltage adding circuit 19 outputs VMT + VBmax, which is a result of adding the voltage corresponding to VMT and the voltage corresponding to VBmax, to the overvoltage limiting circuit 13.

  The following operations and configurations are the same as those in the first and second embodiments. In the first and second embodiments, a voltage dividing and rectifying circuit is provided for each lamp. However, since the voltage to be divided is very high, a high voltage capacitor must be used. Since there are many restrictions such as the distance between parts, there are cases where the circuits as in the first and second embodiments cannot be adopted. In such a case, if the transformers TB1c and 1d having the tertiary winding and the diodes 20a and 20b are used as in the present embodiment, the above-described problem is less likely to occur. On the other hand, since the same voltage as that in the first and second embodiments is detected by the voltage adding circuit 19, the same effect as in the first and second embodiments can be obtained. In other words, the luminance of the lamps Lp1 and Lp2 is made uniform, and the transformer can be used at low cost by reducing the withstand voltage of the transformer.

D. Fourth Embodiment FIG. 7 shows a circuit example of a lamp lighting device according to a fourth embodiment. The lamp lighting device according to the fourth embodiment includes an inverter including a switching circuit, an inverter transformer T2, shunt transformers TB11 to TB1n, voltage dividing and rectifying circuits 22 to 2n, lamps Lp11 to LP1n, and resistors. R21, a lamp voltage detection comparator 26, a lamp current detection comparator 27, an AND circuit 28, and a control circuit 29. The resonance circuit 21 having a resonance frequency higher than the switching frequency in the switching circuit is generated by the leakage component on the secondary winding side of the inverter transformer T2 and the parasitic capacitance between the resonance capacitor, the lamp, and the lamp and the panel. It is configured on the secondary winding side of T2.

  The inverter is connected to the primary winding of the inverter transformer T2. One end of the secondary winding of the inverter transformer T2 is one end of the primary winding and secondary winding of the shunt transformer TB11, one end of the secondary winding of the shunt transformer TB12, and the secondary winding of the shunt transformer TB1n. Connected to one end. The other end of the secondary winding of the inverter transformer T2 is grounded. The other end of the primary winding of the shunt transformer TB11 is connected to the lamp Lp11, and the other end of the secondary winding is connected to one end of the primary winding of the shunt transformer TB12. The other end of the primary winding of the shunt transformer TB12 is connected to the lamp Lp12, and the other end of the secondary winding is connected to one end of the primary winding of the shunt transformer TB1n. The other end of the primary winding of the shunt transformer TB1n is connected to the lamp Lp13, and the other end of the secondary winding of the shunt transformer TB1n is connected to the lamp Lp1n. The other ends of the lamps Lp11 to 1n are connected to one end of a resistor R21, and the other end of the resistor R21 is grounded.

  The connection point between the shunt transformer TB11 and the lamp Lp11 is connected to the voltage dividing and rectifying circuit 22, and the connection point between the shunt transformer TB12 and the lamp Lp12 is connected to the voltage dividing and rectifying circuit 23, and the primary of the shunt transformer TB1n. A connection point between the winding and the lamp Lp13 is connected to the voltage dividing and rectifying circuit 24, and a connection point between the secondary winding of the shunt transformer TB1n and the lamp Lp1n is connected to the voltage dividing and rectifying circuit 2n. In the voltage dividing and rectifying circuits 22 to 2n, capacitors C1 and C2 are connected in series, and one end of C2 is grounded. The cathode of the diode D2 is connected to the connection point between the capacitors C1 and C2, the anode of the diode D2 is connected to the ground, and the anode of the diode D1 is connected to the connection point between the capacitors C1 and C2. The cathode of the diode D1 is the output of the voltage dividing and rectifying circuits 22 to 2n. The outputs of the voltage dividing and rectifying circuits 22 to 2n are output to the lamp voltage detecting comparator 26. The connection point between the lamps Lp11 to Lp1n and the resistor R21 and the lamp current detection comparator 27 are connected.

  The output of the lamp voltage detection comparator 26 and the output of the lamp current detection comparator 27 are input to the AND circuit 28, and the output of the AND circuit 28 is connected to the control circuit 29. The control circuit 29 controls the switching of the switching circuit included in the inverter, and in this case, the control is performed such that the frequency is increased to the resonance frequency of the resonance circuit in the startup mode and is returned to the normal switching frequency when the startup mode ends. To do. Since a certain amount of gain can be obtained without using the resonance frequency, the frequency may be set to a frequency other than the resonance frequency.

  The operation of the circuit shown in FIG. 7 will be described with reference to FIG. First, when the lamp lighting device is turned on as shown in FIG. 8A, the output of the lamp voltage detection comparator 26 and the output of the lamp current detection comparator 27 are ANDed as shown in FIG. 8F. Result is turned off. While the output of the AND circuit 28 is OFF, the control circuit 29 interprets the start mode and sets the switching frequency of the inverter switching circuit to the resonance frequency of the resonance circuit. Note that, since the soft start is performed, the output voltage of the inverter gradually increases. Then, as shown in FIG. 8B, the voltage (ramp voltage) at the connection point between the shunt transformers TB11 to 1n and the lamps Lp11 to 1n gradually increases, and the divided voltage and the output voltage of the rectifier circuits 22 to 2n Gradually increases. Since the lamp voltage is alternating current, the waveform is shown so as to spread vertically in FIG. The ramp voltage detection comparator 26 is supplied with the highest voltage among the output voltages of the voltage dividing and rectifying circuits 22 to 2n. When the output voltage (absolute value) of any one of the voltage dividing and rectifying circuits 22 to 2n exceeds the voltage detection threshold 61 preset in the lamp voltage detection comparator 26, FIG. As shown, the output of the lamp voltage detection comparator 26 is turned on (low active). If there is an unlit lamp, the voltage dividing and output voltages of the rectifier circuits 22 to 2n are higher than when all the lamps are lit. Therefore, the voltage detection threshold 61 is set so that such a state can be detected.

  Further, the lamp current detection comparator 27 takes out the total current (lamp current) flowing through the lamps Lp11 to 1n by the resistor R21, and the lamp current gradually increases by the soft start. As shown in FIG. 8C, when this lamp current exceeds a current detection threshold value 62 preset in the lamp current detection comparator 27, as shown in FIG. The output of the comparator 27 goes high.

  In this way, when only the output of the lamp voltage detection comparator 26 is observed at the start of the start-up stage, the start of the start-up mode is delayed. However, the output of the lamp current detection comparator 27 is low because the initial lamp current does not flow so much, and the output of the lamp voltage detection comparator 26 and the output of the lamp current detection comparator 27 can be combined. The startup mode can be started from the stage when the lamp lighting device is turned on. In the start-up mode, a higher voltage is generated on the secondary winding side of the inverter transformer T2 by the resonance circuit, and the lamp is turned on early. Therefore, it is expected to light up earlier if the start mode is entered early. The lamp current detection threshold 62 is set so that the lamp current exceeds the lamp current detection threshold after the output of the lamp voltage detection comparator 26 becomes low.

  When all the lamps are turned on, the lamp voltage decreases as shown in FIG. When the voltage detection threshold 61 is not reached, the output of the lamp voltage detection comparator 26 becomes high as shown in FIG. That is, as shown in FIG. 8E, since the output of the lamp current detection comparator 27 is high, the output of the AND circuit 28 becomes high as shown in FIG. Switching to the RUN mode (normal mode) is performed. If it does in this way, after confirming lighting of a lamp | ramp, since it transfers to RUN mode, inefficient startup mode can be terminated appropriately. In the control circuit 29, the transition to the RUN mode is detected according to the output of the AND circuit 28, and the switching frequency of the switching circuit is returned to the normal frequency.

  If the end of the activation mode is not instructed even after a predetermined time, there may be a problem with any of the lamps, but here it is assumed that the mode automatically shifts to the RUN mode.

  By performing such a process, it becomes possible to appropriately switch between the start mode and the RUN mode in which the voltage applied to the lamp is increased using resonance.

E. Fifth Embodiment FIG. 9 shows a circuit example of a lamp lighting device according to a fifth embodiment. The lamp lighting device according to the fifth embodiment is a modification of the lamp lighting device according to the fourth embodiment, and a balancer 30 including transformers TB11a to TB1na is provided instead of the shunt transformers TB11 to TB1n. It has been. In the transformers TB11a to TB1na, a voltage in phase with the voltage of the primary winding is generated in the secondary winding. The balancer 30 has the same configuration as the balancer 17 described in the second embodiment.

That is, the first terminal of the primary winding of the transformer TB11a is connected to the inverter transformer T2 via the resonance circuit 21, and the second terminal of the primary winding of the transformer TB11a is connected to the lamp Lp11 and the voltage dividing and rectifying circuit 22. Has been. Similarly, the first terminal of the primary winding of the transformer TB12a is connected to the inverter transformer T2 via the resonance circuit 21, and the second terminal of the primary winding of the transformer TB12a is connected to the lamp Lp12 and the voltage dividing and rectifying circuit 23. It is connected. The first terminal of the primary winding of the transformer TB13a is connected to the inverter transformer T2 via the resonance circuit 21, and the second terminal of the primary winding of the transformer TB13a is connected to the lamp Lp13 and the voltage dividing and rectifying circuit 24. Yes. Further, the first terminal of the primary winding of the transformer TB1na is connected to the inverter transformer T2 via the resonance circuit 21, and the second terminal of the primary winding of the transformer TB1na is connected to the lamp Lp1n and the voltage dividing and rectifying circuit 2n. Has been. The first terminal of the secondary winding of the transformer TB11a is connected to the second terminal of the secondary winding of the transformer TB1na, the second terminal of the secondary winding of the transformer TB11a is trans TB12a two Connected to the first terminal of the next winding. Similarly, the second terminal of the secondary winding of the transformer TB12a is connected to the first terminal of the secondary winding of the transformer TB13a, and the second terminal of the secondary winding of the transformer TB13a is a transformer (not shown). Connected to the first terminal of the secondary winding of TB14a. The second terminal of the secondary winding of the transformer TB1 (n-1) a is connected to the first terminal of the secondary winding of the transformer TB1na.

  That is, the secondary windings of the transformers TB11a and TB1na form a closed loop by connecting terminals having different polarities. In this way, since the currents flowing through the secondary windings of the transformers TB11a and TB1na are the same, the drive currents of the lamps Lp11 to Lp1n flowing through the primary windings of the transformers TB11a and TB1na are also the same. That is, the brightness of the lamps Lp11 to Lp1n is made uniform.

  Other configurations and operations are the same as those of the lamp lighting device according to the fourth embodiment, and a description thereof will be omitted.

F. Sixth Embodiment FIG. 10 shows a circuit example of a lamp lighting device according to a sixth embodiment. The lamp lighting device according to the sixth embodiment is a modification of the lamp lighting device according to the fourth embodiment, and a balancer 30a including capacitors CB1 to CBn is provided instead of the shunt transformers TB11 to TB1n. It has been. One end of the capacitor CB1 is connected to the transformer T2 via the resonance circuit 21, and the other end of the capacitor CB1 is connected to the first terminal of the lamp Lp11. One end of the capacitor CB2 is connected to the transformer T2 via the resonance circuit 21, and the other end of the capacitor CB2 is connected to the first terminal of the lamp Lp12. One end of the capacitor CB3 is connected to the transformer T2 via the resonance circuit 21, and the other end of the capacitor CB3 is connected to the first terminal of the lamp Lp13. One end of the capacitor CB n is connected to the transformer T2 via the resonant circuit 21, the other end of the capacitor CBn is connected to a first terminal of the lamp Lp1n.

  Even with such a configuration, as in the fourth and fifth embodiments, it is possible to appropriately switch between the start mode and the RUN mode that increase the voltage applied to the lamp using resonance. Become.

G. Seventh Embodiment FIG. 11 shows a circuit example of a lamp lighting device according to a seventh embodiment. The lamp lighting device according to the seventh embodiment is a modification of the lamp lighting device according to the fourth embodiment, and includes a balancer 30b having transformers TB11b to TB1nb instead of shunt transformers TB11 to TB1n. In addition, diodes D3 to D6 are provided instead of the voltage dividing and rectifying circuits 22 to 2n. In the transformers TB11b to TB1nb, a voltage in phase with the voltage of the primary winding is generated in the secondary winding and the tertiary winding.

That is, the first pin of the primary winding of the transformer TB11b is connected to the inverter transformer T2 via the resonant circuit 21, a second terminal of the primary winding of the transformer TB11b is connected to the lamp Lp11. Similarly, the first terminal of the primary winding of the transformer TB12b is connected to the inverter transformer T2 via the resonance circuit 21, and the second terminal of the primary winding of the transformer TB12b is connected to the lamp Lp12. The first terminal of the primary winding of the transformer TB13b is connected to the inverter transformer T2 via the resonance circuit 21, and the second terminal of the primary winding of the transformer TB13b is connected to the lamp Lp13. Further, the first terminal of the primary winding of the transformer TB1nb is connected to the inverter transformer T2 via the resonance circuit 21, and the second terminal of the primary winding of the transformer TB1nb is connected to the lamp Lp1n. The first terminal of the secondary winding of the transformer TB11b is connected to the second terminal of the secondary winding of the transformer TB1nb, and the second terminal of the secondary winding of the transformer TB11b is the second terminal of the transformer TB12b. Connected to the first terminal of the next winding. Similarly, the second terminal of the secondary winding of the transformer TB12b is connected to the first terminal of the secondary winding of the transformer TB13b, and the second terminal of the secondary winding of the transformer TB13b is a transformer (not shown). Connected to the first terminal of the secondary winding of TB14b. The second terminal of the secondary winding of the transformer TB1 (n−1) b is connected to the first terminal of the secondary winding of the transformer TB1nb.

  That is, the secondary windings of the transformers TB11b and TB1nb form a closed loop by connecting terminals having different polarities. In this way, since the currents flowing through the secondary windings of the transformers TB11b and TB1nb are the same, the drive currents of the lamps Lp11 to Lp1n flowing through the primary windings of the transformers TB11b and TB1nb are also the same. That is, the brightness of the lamps Lp11 to Lp1n is made uniform.

  Further, the first terminal of the tertiary winding of the transformer TB11b is connected to the anode of the diode D3. The second terminal of the tertiary winding of the transformer TB11b is grounded. The first terminal of the tertiary winding of the transformer TB12b is connected to the anode of the diode D4. The second terminal of the tertiary winding of the transformer TB12b is grounded. The first terminal of the tertiary winding of the transformer TB13b is connected to the anode of the diode D5. The second terminal of the tertiary winding of the transformer TB13b is connected. The first terminal of the tertiary winding of the transformer TB1nb is connected to the anode of the diode D6. The second terminal of the tertiary winding of the transformer TB1nb is grounded. The cathodes of the diodes D3 to D6 are connected to each other and further connected to the input terminal of the lamp voltage detection comparator 26.

  A voltage corresponding to the voltage of the primary winding is generated in the tertiary windings of the transformers TB11b to TB1nb. Since the cathodes of the diodes D3 to D6 connected to the tertiary windings of the transformers TB11b to TB1nb are connected, the maximum voltage generated in the tertiary windings of the transformers TB11b to TB1nb, that is, according to the primary winding The maximum voltage occurs among the voltages. When such a circuit is employed, unlike the fourth to sixth embodiments, the lamp voltage is not detected. However, the detected voltage is a voltage according to the lamp voltage, and the operation is the same as that of the fifth embodiment if the threshold value is set appropriately.

  In the fifth and sixth embodiments, a voltage dividing and rectifying circuit is provided for each lamp. However, since the voltage to be divided is very high, a high voltage capacitor must be used. Since there are many restrictions such as the distance between parts in the circuit, there are cases where the circuits as in the fifth and sixth embodiments cannot be adopted. In such a case, if the transformers TB11b and 1nb having the tertiary winding and the diodes D3 to D6 are used as in the present embodiment, the above problem does not occur. Even in the tertiary winding, it is possible to detect a change in the voltage in the primary winding that occurs according to the lamp voltage, and the lamp voltage detection comparator 26 can detect the lamp voltage unbalanced state via the diodes D3 to D6. It is like that.

H. Eighth Embodiment FIG. 12 shows a circuit example of a lamp lighting device according to an eighth embodiment. The lamp lighting device according to the eighth embodiment includes a first inverter including a switching circuit, a second inverter including a switching circuit, a first inverter transformer T3, a second inverter transformer T4, and 1 Compared to shunt transformers TB21 to TB2n having primary to tertiary windings, shunt transformers TB31 to TB3n having primary to tertiary windings, diodes D11 to D1n, diodes D21 to D2n, and lamps Lp31 to LP3n And a control circuit 32. In the shunt transformers TB21 to TB2n and TB31 to TB3n, voltages having the same phase as the voltage of the primary winding are generated in the secondary winding and the tertiary winding.

  The first inverter is connected to the primary winding of the first inverter transformer T3. The circuit surrounded by the one-dot chain line including the first inverter is a master circuit. One end of the secondary winding of the first inverter transformer T3 is one end of the primary winding and secondary winding of the shunt transformer TB21, one end of the secondary winding of the shunt transformer TB22, and the secondary of the shunt transformer TB2n. Connected to one end of the winding. The other end of the secondary winding of the first inverter transformer T3 is grounded. The other end of the primary winding of the shunt transformer T21 is connected to the lamp Lp31, and the other end of the secondary winding is connected to one end of the primary winding of the shunt transformer T22. The other end of the primary winding of the shunt transformer T22 is connected to the lamp Lp32, and the other end of the secondary winding is connected to one end of the primary winding of the shunt transformer T2n. The other end of the primary winding of the shunt transformer T2n is connected to the lamp Lp3n, and the other end of the secondary winding of the shunt transformer T2n is connected to one end of the secondary winding of the shunt transformer T3n.

  The second inverter is connected to the primary winding of the second inverter transformer T4. The circuit surrounded by the one-dot chain line including the second inverter is a slave circuit. One end of the secondary winding of the second inverter transformer T4 is one end of the primary winding and the secondary winding of the shunt transformer TB31, one end of the secondary winding of the shunt transformer TB32, and the secondary of the shunt transformer TB3n. Connected to the other end of the winding. The other end of the secondary winding of the second inverter transformer T4 is grounded. The other end of the primary winding of the shunt transformer TB31 is connected to the lamp Lp31, and the other end of the secondary winding is connected to one end of the primary winding of the shunt transformer TB32. The other end of the primary winding of the shunt transformer TB32 is connected to the lamp Lp32, and the other end of the secondary winding is connected to the primary winding of the shunt transformer TB3n. The other end of the primary winding of the shunt transformer TB3n is connected to the lamp Lp3n, and the other end of the secondary winding of the shunt transformer TB3n is connected to one end of the secondary winding of the shunt transformer TB2n. Thus, the lamps Lp31 to Lp3n are differentially driven. That is, the first inverter and the second inverter oscillate with the phase inverted by 180 °. Further, the secondary windings of the shunt transformers TB21 to TB2n are configured to connect terminals having different polarities. Similarly, the secondary windings of the shunt transformers TB31 to TB3n are connected to terminals having different polarities. Furthermore, terminals of the same polarity are connected to the secondary winding of the shunt transformer TB2n and the secondary winding of the shunt transformer TB3n.

  Furthermore, one end of the tertiary winding of the shunt transformer TB21 is connected to the anode of the diode D11, and the other end is grounded. The cathode of the diode D11 is input to the comparator 31. One end of the tertiary winding of the shunt transformer TB22 is connected to the anode of the diode D12, and the other end is grounded. The cathode of the diode D12 is input to the comparator 31. One end of the tertiary winding of the shunt transformer TB2n is connected to the anode of the diode D1n, and the other end is grounded. The cathode of the diode D1n is input to the comparator 31. Furthermore, one end of the tertiary winding of the shunt transformer TB31 is connected to the anode of the diode D21, and the other end is grounded. The cathode of the diode D21 is input to the comparator 31. One end of the tertiary winding of the shunt transformer TB32 is connected to the anode of the diode D22, and the other end is grounded. The cathode of the diode D22 is input to the comparator 31. One end of the tertiary winding of the shunt transformer TB3n is connected to the anode of the diode D2n, and the other end is grounded. The cathode of the diode D2n is input to the comparator 31.

  The output of the comparator 31 is input to the control circuit 32, and the output of the control circuit 32 controls the first and second inverters.

  As described above, since the shunt transformers TB21 to 2n and the shunt transformers TB31 to 3n are all connected not only in the master circuit but also in the slave circuit, the currents flowing through the lamps Lp31 to Lp3n are made uniform. . Accordingly, the luminance at both ends of the lamps Lp31 to Lp3n is also made uniform. In the lamp lighting circuit of FIG. 12, the tertiary windings of the shunt transformers TB21 to 2n and the shunt transformers TB31 to 3n detect the voltage generated in each shunt transformer, and this voltage signal is diode-OR connected. Are input to the comparator 31.

If the terminals of the secondary winding of the first inverter transformer T3 of the master circuit are short-circuited, for example, by a human touch, the output voltage of the first inverter transformer T3 decreases. Then, since also the second inverter transformer T4 is operated in the first inverter transformer T3 in parallel driven same duty over the slave circuit, the output voltage of the first inverter transformer T3, the second inverter transformer T4 It becomes lower than the output voltage. Thus, when a voltage difference is generated between the outputs of the first and second inverter transformers, a difference is generated between the lamp current on the master circuit side and the lamp current on the slave circuit side. At this time, in the shunt transformer, a voltage is generated to make the lamp current on the master circuit side coincide with the lamp current on the slave circuit side, and an attempt is made to balance the current.

  As a result, a voltage higher than that during normal operation is generated in the tertiary winding in the shunt transformer, and this voltage can be detected by the comparator 31. When the voltage variation is detected, the comparator 31 outputs a detection signal to the control circuit 32, and the control circuit 32 responds to the detection signal to the switching circuit included in the first and second inverters. Stop switching. The output of the comparator 31 is latched and continues until the power is turned on again. Further, not only when a problem occurs in the inverter transformer T3 or T4, but also when a problem occurs in any one of the lamps Lp31 to 3n, for example, the current flowing through the shunt transformer is fluctuated. Can be detected.

  In the example of FIG. 12, the current is detected by providing a tertiary winding in each shunt transformer, but it may be detected by another method. In addition, since the shunt transformer in the master circuit and the shunt transformer in the slave circuit are connected, an operation for equalizing the current flowing in all the shunt transformers is performed. Therefore, when an imbalance occurs in any one of the shunt transformers, the influence is exerted on other shunt transformers. Therefore, if a circuit for detecting a change in current is provided in at least one of the shunt transformers, the occurrence of a problem can be detected as a result.

  Thus, according to the eighth embodiment, the abnormality of the lamp lighting circuit is detected and the operation of the lamp lighting circuit is stopped, so that the safety can be improved. Moreover, safety may be improved by limiting the output current without stopping. Note that there may be one inverter transformer.

I. Ninth Embodiment FIG. 13 shows a circuit example of a lamp lighting device according to a ninth embodiment. The lamp lighting device according to the ninth embodiment is a modification of the lamp lighting device according to the eighth embodiment, and instead of the shunt transformers TB21 to TB22, transformers TB21a to TB2na are used. Transformers TB31a to TB3na are used instead of TB31 to TB3n. In the transformers TB21a to TB2na and the transformers TB31a to TB3na, a voltage having the same polarity as the voltage of the primary winding is generated in the secondary winding and the tertiary winding.

  The first terminal of the primary winding of the transformer TB21a is connected to the first terminal of the transformer T3, and the second terminal of the primary winding of the transformer TB21a is connected to the first terminal of the lamp Lp31. The first terminal of the primary winding of the transformer TB22a is connected to the first terminal of the transformer T3, and the second terminal of the primary winding of the transformer TB22a is connected to the first terminal of the lamp Lp32. The first terminal of the primary winding of the transformer TB2na is connected to the first terminal of the transformer T3, and the second terminal of the primary winding of the transformer TB2na is connected to the first terminal of the lamp Lp3n. Further, the first terminal of the primary winding of the transformer TB31a is connected to the first terminal of the transformer T4, and the second terminal of the primary winding of the transformer TB31a is connected to the second terminal of the lamp Lp31. Yes. The first terminal of the primary winding of the transformer TB32a is connected to the first terminal of the transformer T4, and the second terminal of the primary winding of the transformer TB32a is connected to the second terminal of the lamp Lp32. The first terminal of the primary winding of the transformer TB3na is connected to the first terminal of the transformer T4, and the second terminal of the primary winding of the transformer TB3na is connected to the second terminal of the lamp Lp3n.

The first terminal of the secondary winding of the transformer TB21a is connected to the first terminal of the secondary winding of the transformer TB31a. These terminals are terminals having the same polarity. On the other hand, the second terminal of the secondary winding of the transformer TB21a is connected to the first terminal of the secondary winding of the transformer TB22a. The second terminal of the secondary winding of the transformer TB22a is connected to the first terminal of the secondary winding of the transformer TB23a (not shown). The second terminal of the secondary winding of the transformer TB2 (n-1) a is connected to the first terminal of the secondary winding of the transformer TB2na. As described above, the secondary windings of the upper transformers TB21a to TB2na are connected to terminals having different polarities.

  Further, the second terminal of the secondary winding of the transformer TB2na is connected to the second terminal of the secondary winding of the transformer TB3na. These terminals are terminals having the same polarity. On the other hand, the first terminal of the secondary winding of the transformer TB3na is connected to the second terminal of the secondary winding of the transformer TB3 (n-1) a (not shown). The first terminal of the secondary winding of the transformer TB33a is connected to the second terminal of the secondary winding of the transformer TB32a. The first terminal of the secondary winding of the transformer TB32a is connected to the second terminal of the secondary winding of the transformer TB31a. In this way, the secondary windings of the lower transformers TB31a to TB3na are connected to terminals having different polarities.

  As described in the eighth embodiment, since the lamps Lp31 to Lp3n are differentially driven, the upper transformers TB21a to TB2na and the lower transformers TB31a to TB3na are driven with different polarities. Therefore, although the terminals of the same polarity are connected to the secondary winding of the transformer TB21a and the secondary winding of the transformer TB31a, since the lamp LP31 is driven differentially, terminals having different polarities are actually used. Is connected. Similarly, the same polarity terminal is connected to the secondary winding of the transformer T2na and the secondary winding of the transformer TB3na. However, since the lamp LP3n is differentially driven, the actual polarity is different. They are connected to each other. That is, the secondary windings of the transformers TB21a to TB2na and the secondary windings of the transformers TB31a to TB3na constitute a closed loop, but terminals having different polarities are connected to each other.

  In the ninth embodiment, the lamps Lp31 to Lp3n are differentially driven in this way to equalize the currents flowing through the lamps, and to uniform the brightness of the lamps Lp31 to Lp3n.

  The configuration and operation of the other parts are the same as in the eighth embodiment.

  Although the embodiment of the present invention has been described above, the present invention is not limited to this, and for example, the above-described embodiments can be arbitrarily combined. Further, in accordance with the above-described purpose, there may be a case where the circuit can be partially replaced with another circuit having the same function.

It is a figure which shows the example of the conventional lamp lighting circuit. It is a figure which shows the lamp lighting circuit in the 1st Embodiment of this invention. It is a figure for demonstrating the principle in the 1st Embodiment of this invention. It is a figure showing the effect in the 1st Embodiment of this invention. It is a figure which shows the lamp lighting circuit in the 2nd Embodiment of this invention. It is a figure which shows the lamp lighting circuit in the 3rd Embodiment of this invention. It is a figure which shows the lamp lighting circuit in the 4th Embodiment of this invention. (A) thru | or (f) is a signal waveform diagram for demonstrating operation | movement of the lamp lighting circuit in the 4th Embodiment of this invention. It is a figure which shows the lamp lighting circuit in the 5th Embodiment of this invention. It is a figure which shows the lamp lighting circuit in the 6th Embodiment of this invention. It is a figure which shows the lamp lighting circuit in the 7th Embodiment of this invention. It is a figure which shows the lamp lighting circuit in the 8th Embodiment of this invention. It is a figure which shows the lamp lighting circuit in the 9th Embodiment of this invention.

Explanation of symbols

T1, T2, T3, T4 Inverter transformers TB1, TB11, TB12, TB1n, TB21, TB22, TB2n, TB31, TB32, TB3n, TB11a, TB12a, TB1na, TB21a, TB22a, TB2na, TB11b, TB11b, TB12b, TB12b, TB12b, TB12b , TB3na Shunt transformer, Transformer 13 Overvoltage limiting circuit 14 Constant current control circuit CB1, CB2, CB3, CBn Capacitor D3, D4, D5, D6 Diode 18 Voltage dividing and rectifying circuit 19 Voltage adding circuit 17, 30, 30a, 30b Balancer Lp1, Lp2, Lp11, Lp12, Lp13, Lp1n, Lp31, Lp32, Lp3n lamp

Claims (3)

A first balancer including a first transformer, wherein one end of a primary winding of the first transformer is connected to one end of a specific lamp among the plurality of lamps, and equalizes current flowing through the plurality of lamps. When,
A first transformer including a second transformer, wherein one end of a primary winding of the second transformer is connected to the other end of the specific lamp among the plurality of lamps, and the current flowing through the plurality of lamps is made uniform. 2 balancers,
Means connected to one end of the secondary winding of the first transformer and one end of the secondary winding of the second transformer, and for supplying a voltage so as to be in opposite phases to both ends of the plurality of lamps; ,
Have
The other end of the secondary winding of the specific first transformer of the first transformer and the other end of the secondary winding of the specific second transformer of the second transformer are connected,
The other end of the secondary winding of the first transformer other than the specific first transformer is connected to the other end of the primary winding of any one of the first transformers other than the first transformer. ,
The other end of the secondary winding of the second transformer other than the specific second transformer is connected to the other end of the primary winding of any one of the second transformers other than the second transformer. Lamp lighting device. A first balancer including a first transformer, wherein one end of a primary winding of the first transformer is connected to one end of a specific lamp among the plurality of lamps, and equalizes current flowing through the plurality of lamps. When,
A first transformer including a second transformer, wherein one end of a primary winding of the second transformer is connected to the other end of the specific lamp among the plurality of lamps, and the current flowing through the plurality of lamps is made uniform. 2 balancers,
Means connected to the other end of the primary winding of the first transformer and the other end of the primary winding of the second transformer, and for supplying a voltage to both ends of the plurality of lamps in opposite phases to each other; ,
Have
A plurality of the first transformer and the second transformer;
The first transformers are connected in series with secondary windings having different polarities,
The second transformers are connected in series with secondary windings having different polarities,
A lamp lighting device, wherein at least one secondary winding of the first transformer and at least one secondary winding of the second transformer are connected in series in the same polarity relationship. A first balancer including a first transformer, wherein one end of a primary winding of the first transformer is connected to one end of a specific lamp among the plurality of lamps, and equalizes current flowing through the plurality of lamps. When,
A first transformer including a second transformer, wherein one end of a primary winding of the second transformer is connected to the other end of the specific lamp among the plurality of lamps, and the current flowing through the plurality of lamps is made uniform. 2 balancers,
Means connected to the other end of the primary winding of the first transformer and the other end of the primary winding of the second transformer, and for supplying a voltage to both ends of the plurality of lamps in opposite phases to each other; ,
Have
The first balancer has a plurality of first transformers;
The secondary winding of the first transformer is connected to a terminal of a different polarity of the secondary winding of any other of the first transformer in the first balancer;
The second balancer has a plurality of second transformers;
The secondary winding of the second transformer is connected to a terminal of a different polarity of the secondary winding of any other second transformer in the second balancer;
The lamp lighting device, wherein the secondary winding of the transformer in the first balancer and the secondary winding of the transformer in the second balancer are connected to form a closed loop.

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