JP2007207700A - Discharge tube lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge tube lighting device capable of establishing synchronization without arranging a base winding on a transformer, simple in extinguishing control of the discharge tube, and capable of saving power and space. <P>SOLUTION: Each inverter unit 14 formed by connecting and arranging a transformer driving circuit part 11, a transformer 12 and the discharge tube 13 is composed, and a plurality of the inverter units 14 are respectively connected to one transmission circuit part 15 through switch circuit parts 16 of a number equal to the number thereof. In addition, an extinguishing control circuit part 17 is connected to the respective switch circuit parts 16. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a discharge tube lighting device for lighting a plurality of discharge tubes, and more particularly to a discharge tube lighting device having a brightness adjusting function.

  A display device using a liquid crystal panel usually lights a discharge tube such as a cold cathode tube as a backlight for illuminating the back surface of the liquid crystal panel. In order to light a discharge tube such as a cold cathode tube, a discharge tube lighting device that generates a high voltage and supplies it to the discharge tube is used. This discharge tube lighting device includes an oscillation circuit section called an inverter for liquid crystal backlight, a circuit section including a step-up transformer and the like, and a discharge tube.

  In recent years, the number of cold-cathode tubes used in one liquid crystal panel display device is increasing with the increase in the screen of the liquid crystal panel. A discharge tube lighting device for lighting a plurality of discharge tubes has a dimming function for controlling the brightness of the discharge tubes in a state where all of the plurality of discharge tubes are lit in order to control the brightness of the liquid crystal panel display. is doing. This dimming function is generally performed by controlling the voltage applied to the discharge tube, but the controllable range is limited due to the restrictions on the characteristics of the discharge tube. In particular, there is a limit to dimming that reduces the brightness of the discharge tube.

  On the other hand, in the liquid crystal panel display device, in order to save power, it is necessary to perform control for suppressing the brightness further than in the past. Therefore, there has been proposed a method of dimming by turning off some of the plurality of lighted discharge tubes as necessary. FIG. 1 is a circuit diagram of a conventional discharge tube lighting device. The discharge tube lighting device shown in FIG. 1 has a function of turning on four cold cathode tubes 1 and turning off two of them.

  As shown in FIG. 1, the conventional discharge tube lighting device selects one of the two transmission circuit units 2 with the switch 5 and outputs the signal output from either one of the transmission circuit units 2 with four transformers 3. The voltage is boosted by the transformer 4 and the four cold cathode tubes 1 connected to the transformers 3 and 4 are turned on. Further, the circuit configuration is such that dimming is performed by turning off two of the four cold-cathode tubes 1 by the on / off operation of the switch 6.

  Further, the drive signals for lighting the discharge tubes 1 must be synchronized. In the discharge tube lighting device shown in FIG. 1, a base winding 7 is provided in the transformer 3 and a feedback signal is sent to the transmission circuit unit 2. It is configured. A discharge tube lighting device using such an electromagnetic transformer is disclosed in Patent Document 1.

JP 2001-319793 A

  However, in the configuration as shown in FIG. 1, a plurality of oscillation circuits exist and the circuit is complicated, and the base 3 is required for the transformer 3 to synchronize the drive signals. There is a problem of becoming larger. Further, the lighting of each discharge tube is controlled by operating the four switches 5 and 6, but there is a problem that the method of controlling the switches becomes complicated and the circuit scale becomes large.

  Therefore, an object of the present invention is to solve the above-described problems of the prior art. Specifically, it is an object of the present invention to provide a discharge tube lighting device that can synchronize without arranging a base winding in a transformer, can be easily controlled to turn off the discharge tube, and save power and space.

  The present invention employs the following means in order to solve the problems of the prior art. That is, according to the present invention, a switch circuit unit is provided in front of the transformer driving circuit unit, and the discharge circuit is turned off by controlling the switch circuit unit according to a turn-off signal from the turn-off control circuit unit, so that the oscillation circuit is united. The gist is to enable synchronization even if the transformer does not have a base winding.

  According to the present invention, an oscillation circuit unit that outputs a drive signal, a plurality of inverter units that are connected to the oscillation circuit unit, a discharge tube that is connected to the inverter unit and lights up, and a light-off control circuit that outputs a light-off signal And a switching circuit portion connected between the turn-off control circuit portion and each of the inverter units, and the inverter unit outputs a driving voltage according to the driving signal; A transformer that boosts the drive voltage and outputs the boosted voltage to the discharge tube, the discharge tube is turned on by the boosted drive voltage output from the transformer, and the turn-off control circuit unit includes the plurality of inverters The extinguishing signal is output from the unit to the switch circuit unit connected to the inverter unit selected in advance, and the switch circuit unit Discharge tube lighting apparatus characterized by stopping the operation of said transformer drive circuit unit in the inverter unit according to the signal to turn off the discharge tube is obtained.

  A discharge tube lighting device according to the present invention includes an oscillation circuit unit that outputs an optimal drive signal for driving a transformer, and an inverter unit that includes a transformer drive circuit unit and a transformer. The inverter unit is connected to one of the oscillation circuit units, and each inverter unit has a basic configuration in which a discharge tube is connected. Furthermore, the discharge tube lighting device according to the present invention includes a turn-off control circuit unit that outputs a turn-off signal for turning off a discharge tube connected to the inverter unit by stopping the operation of the inverter unit selected in advance. And a switch circuit unit that operates in response to the turn-off signal and stops the operation of the inverter unit.

  The transformer drive circuit unit receives the drive signal and outputs a drive voltage for driving the transformer to the transformer. The transformer uses the drive voltage output from the transformer drive circuit unit as an input voltage and boosts and outputs the drive voltage at a set boost ratio. The discharge tube is lit with an output voltage output from the transformer.

  The transformer drive circuit section and the transformer constitute a continuous set of inverter units. By connecting a plurality of the inverter units to one oscillation circuit unit, it becomes possible to light a large number of discharge tubes with only one drive signal output from one oscillation circuit unit. Further, an extinguishing control circuit unit that outputs an extinguishing signal for extinguishing a preselected discharging tube among the plural discharging tubes is provided, and a switch circuit unit that operates according to the extinguishing signal is connected to the inverter unit By disposing, the operation of the inverter unit to which the discharge tube is connected can be stopped and the discharge tube can be controlled to be turned off.

  The extinguishing control circuit unit outputs an extinguishing signal for extinguishing a discharge tube preset by a program or the like to the switch circuit unit. The switch circuit unit may have a function of stopping the operation of the inverter unit in accordance with the turn-off signal, and may have a function of stopping the operation of the transformer drive circuit unit.

  The transformer only needs to have means for boosting the drive voltage to a predetermined voltage to light the discharge tube, and may be an electromagnetic transformer in which a magnetic material is wound, a piezoelectric transformer made of a piezoelectric ceramic material, or the like.

  According to the present invention, an oscillation circuit unit that outputs a drive signal, a plurality of inverter units that are connected to the oscillation circuit unit, a discharge tube that is connected to the inverter unit and lights up, and a light-off control circuit that outputs a light-off signal A switch circuit portion connected between the turn-off control circuit portion and each of the inverter units, the inverter unit amplifying the drive signal and outputting an amplified signal; and A transformer driving circuit unit that outputs a driving voltage in response to the amplified signal and a transformer that boosts the driving voltage and outputs the boosted voltage to the discharge tube. The discharge tube is a boosted drive output from the transformer. The switch circuit that is turned on by a voltage and that is connected to an inverter unit preselected from the plurality of inverter units. The discharge tube lighting device is characterized by outputting the extinguishing signal to the switch circuit unit, wherein the switch circuit unit stops the operation of the amplifier circuit unit in the inverter unit in response to the extinguishing signal and extinguishes the discharge tube. can get.

  A discharge tube lighting device according to the present invention has an oscillation circuit section that outputs an optimal drive signal for driving a transformer, and has an inverter unit that includes an amplifier circuit section, a transformer drive circuit section, and a transformer. A plurality of inverter units are connected to one oscillation circuit section, and each inverter unit has a basic configuration in which a discharge tube is connected. Furthermore, the discharge tube lighting device according to the present invention includes a turn-off control circuit unit that outputs a turn-off signal for turning off a discharge tube connected to the inverter unit by stopping the operation of the inverter unit selected in advance. And a switch circuit unit that operates in response to the turn-off signal and stops the operation of the inverter unit.

  The amplifier circuit unit amplifies the drive signal and outputs an amplified signal. The transformer driving circuit unit receives the amplified signal and outputs a driving voltage for driving the transformer to the transformer. The transformer uses the drive voltage output from the transformer drive circuit unit as an input voltage and boosts and outputs the drive voltage at a set boost ratio. The discharge tube is lit with an output voltage output from the transformer.

  The amplifier circuit unit, the transformer drive circuit unit, and the transformer constitute a continuous set of inverter units. By connecting a plurality of the inverter units to one oscillation circuit unit, it becomes possible to light a large number of discharge tubes with only one drive signal output from one oscillation circuit unit. Further, an extinguishing control circuit unit that outputs an extinguishing signal for extinguishing a preselected discharging tube among the plural discharging tubes is provided, and a switch circuit unit that operates according to the extinguishing signal is connected to the inverter unit By disposing, the operation of the inverter unit to which the discharge tube is connected can be stopped and the discharge tube can be controlled to be turned off.

  The extinguishing control circuit unit outputs an extinguishing signal for extinguishing a discharge tube preset by a program or the like to the switch circuit unit. The switch circuit unit may have a function of stopping the operation of the inverter unit according to the turn-off signal, and may have a function of stopping the operation of the amplifier circuit unit.

  The transformer only needs to have means for boosting the drive voltage to a predetermined voltage to light the discharge tube, and may be an electromagnetic transformer in which a magnetic material is wound, a piezoelectric transformer made of a piezoelectric ceramic material, or the like.

  According to the present invention, the inverter unit is connected to the oscillation circuit unit via the switch circuit unit, and the switch circuit unit cuts off the drive signal input to the inverter unit according to the turn-off signal or A discharge tube lighting device characterized by being connected and arranged so as to be connected to the ground is obtained.

  In the discharge tube lighting device according to the present invention, a switch circuit unit is connected and arranged at the subsequent stage of the oscillation circuit unit and at the previous stage of the inverter unit. The switch circuit unit operates according to the extinguishing signal output from the extinguishing control circuit unit, and functions to stop the operation of the inverter unit by cutting off or connecting the drive signal output from the oscillation circuit unit to ground Have

  As described above, according to the present invention, there is provided a discharge tube lighting device that can synchronize without arranging a base winding in a transformer, is simple in discharge tube turn-off control, and realizes power saving and space saving. can get.

  A discharge tube lighting device according to the present invention is connected to an oscillation circuit unit that outputs a drive signal, a transformer drive circuit unit that outputs a drive voltage according to the drive signal, a transformer that boosts the drive voltage, and the transformer. A discharge tube, a turn-off control circuit unit that outputs a turn-off signal, and a switch circuit unit, and the switch circuit unit is controlled by the turn-off signal so that the discharge tube is turned off.

  Hereinafter, a specific example is given and the discharge tube lighting device of the present invention is described in more detail with reference to the drawings.

Example 1
FIG. 2 is a block diagram of the discharge tube lighting device according to the first embodiment. The discharge tube lighting device according to the first embodiment includes an inverter unit 14 in which a transformer drive circuit unit 11, a transformer 12, and a discharge tube 13 are connected and arranged, and a plurality of inverter units 14 are connected to the same number of switch circuit units 16 respectively. One transmitter circuit unit 15 was connected. Further, the light-off control circuit unit 17 is connected to each switch circuit unit 16.

  The transmission circuit unit 15 generates a voltage having a frequency necessary for lighting the discharge tube. The transformer drive circuit unit 11 is a full bridge circuit composed of switching elements, and outputs a drive voltage for driving the transformer 12. The transformer 12 boosts the drive voltage output from the transformer drive circuit unit 11 and outputs the boosted voltage to the discharge tube 13 to light the discharge tube 13. The step-up ratio of the transformer 12 is set according to the specifications of the discharge tube to be used. In the first embodiment, the step-up ratio of the drive voltage and the transformer 12 is set so that an output of 2 kVpp is obtained.

  As the discharge tube 13, a cold cathode tube is generally used, but also in this embodiment, a cold cathode tube having a length of 500 mm and a tube diameter of 2.5 mm was used. A plurality of inverter units 14 in which the transformer driving circuit unit 11 and the transformer 12 are connected and arranged are arranged, and each inverter unit 14 in which the discharge tube 13 is connected to the transformer 12 is connected to one transmission circuit unit 15 via the switch circuit unit 16. Connect to. The switch circuit unit 16 is composed of a switching element. All the switch circuit sections 16 are connected to the extinction control circuit section 17, and the switching element is configured to perform a switching operation by an extinction signal output from the extinction control circuit section 17.

  The extinguishing control circuit unit 17 outputs an extinguishing signal according to a preset extinguishing control operation, and this signal is determined by the configuration of the switch circuit unit 16. In the first embodiment, processing using a digital signal that outputs a high level when the discharge tube is turned on and outputs a low level when the discharge tube is turned on is adopted.

  When the switching element constituting the switch circuit unit 16 receives the low level signal output from the extinguishing control circuit unit 17, the switching operation is released and the drive signal output from the transmission circuit unit is connected to the inverter unit 14 side. Shut off the circuit to be turned on. Thus, the discharge tube 13 connected to the inverter unit 14 is turned off.

  Since the turn-off signal can be set for each of the plurality of inverter units 14 arranged, any discharge tube can be turned off at any timing. Further, since the discharge tubes are lit by the drive signal of one transmission circuit unit, it is not necessary to synchronize the discharge tubes. Therefore, it is not necessary to provide the transformer 12 with a base winding for generating a feedback signal. Further, in the first embodiment, since only one transmission circuit unit is required, a discharge tube lighting device having a simple circuit configuration and easy control can be obtained.

(Example 2)
FIG. 3 is a block diagram of the discharge tube lighting device according to the second embodiment. As in the first embodiment, the discharge tube lighting device according to the second embodiment forms an inverter unit 14 in which a transformer drive circuit unit 11 and a transformer 12 are connected and arranged. A plurality of inverter units 14 each having a discharge tube 13 connected to the transformer 12 were connected to the same transmission circuit unit 15 through the same number of passive element units 18 as the inverter units 14. The switch circuit unit 16 is disposed between the passive element unit 18 and the transformer drive circuit unit 11 and connected to the ground 19. Further, the light-off control circuit unit 17 is connected to each switch circuit unit 16.

  Since the discharge tube lighting device according to the second embodiment has the above-described configuration, each switch circuit unit 16 according to a turn-off signal output from the turn-off control circuit unit 17 according to a preset turn-off control operation as in the first embodiment. Works. When each switch circuit unit 16 receives the turn-off signal, the switch circuit unit 16 causes the drive signal output from the transmission circuit unit 15 to flow to the ground 19 side via the passive element unit 18 formed of a resistor element, a capacitor, a diode, and the like, and thereby the inverter unit. 14 has a function of stopping the operation.

  In the second embodiment, as in the first embodiment, since a turn-off signal can be set for each of the plurality of inverter units 14 arranged, any discharge tube can be turned off at any timing. Further, since the discharge tube is lit by a drive signal of one transmission circuit unit, it is not necessary to synchronize the lighting of each discharge tube, so that a special feedback signal is also generated for the transformer 12. There is no need to provide a base winding. Further, in the second embodiment, as in the first embodiment, only one transmitting circuit unit is sufficient, and the discharge tube lighting device is simple in circuit configuration and easy to control.

(Example 3)
FIG. 4 is a block diagram of the discharge tube lighting device according to the third embodiment. The discharge tube lighting device according to the third embodiment includes an inverter unit 20 in which an amplifier circuit unit 21, a transformer drive circuit unit 11, and a transformer 12 are connected, and a plurality of inverter units 20 in which a discharge tube 13 is connected to the transformer 12 are provided. Each was connected to the same transmission circuit unit 15. The switch circuit unit 16 is connected to the amplifier circuit unit 21. Further, the light-off control circuit unit 17 is connected to each switch circuit unit 16.

  The amplifier circuit unit 21 is an amplifier circuit using a general semiconductor element that amplifies the drive signal output from the transmission circuit unit 15. Since the discharge tube lighting device according to the third embodiment is configured as described above, each switch circuit unit 16 is configured in accordance with a turn-off signal output from the turn-off control circuit unit 17 according to a preset turn-off control operation, as in the first embodiment. Works. Each switch circuit unit 16 has a function of stopping the operation of the inverter unit 20 by stopping the operation of the amplifier circuit unit 21 when receiving the turn-off signal.

  In the third embodiment, as in the first embodiment, since the turn-off signal can be set for each of the plurality of inverter units 20 arranged, any discharge tube can be turned off at any timing. Further, since the discharge tube is lit by a drive signal of one transmission circuit unit, it is not necessary to synchronize the lighting of each discharge tube, so that a special feedback signal is also generated for the transformer 12. There is no need to provide a base winding. Further, in the third embodiment, as in the first embodiment, only one transmitting circuit unit is sufficient, and the discharge tube lighting device is simple in circuit configuration and easy to control.

Example 4
FIG. 5 is a block diagram of a discharge tube lighting device according to the fourth embodiment. In the discharge tube lighting device according to the fourth embodiment, the amplifier circuit unit 21, the transformer drive circuit unit 11, and the transformer 12 are connected to each other to form the inverter unit 20, and the plurality of inverters in which the discharge tube 13 is connected to the transformer 12 The unit 20 was connected to the same transmission circuit unit 15 through the same number of passive element units 18 made up of resistance elements, capacitors, diodes and the like. The switch circuit unit 16 is connected between the amplifier circuit unit 21 and the ground 19. Further, the light-off control circuit unit 17 is connected to each switch circuit unit 16.

  Since the discharge tube lighting device according to the fourth embodiment has the above-described configuration, each switch circuit unit 16 according to a turn-off signal output from the turn-off control circuit unit 17 according to a preset turn-off control operation as in the first embodiment. Works. Each switch circuit unit 16 has a function of stopping the operation of the inverter unit 20 by stopping the operation of the amplifier circuit unit 21 when receiving the turn-off signal.

  FIG. 6 is a circuit diagram of a discharge tube lighting device according to the fourth embodiment. FIG. 6 is a circuit diagram specifically showing a part of the block diagram of the discharge tube lighting device according to the fourth embodiment shown in FIG. The transformer drive circuit unit 11 forms a full bridge circuit using four field effect transistors, and the terminal 26 is connected to a DC power source. This is a drive circuit for driving the transformer 12, and the terminal 27 is connected to a DC power source. The transformer 12 is a piezoelectric transformer made of a lead zirconate titanate-based piezoelectric ceramic material, and a discharge tube is connected to the output terminal 23, but the discharge tube is not shown.

  The amplifier circuit unit 21 is an amplifier circuit configured by a transistor that amplifies a drive signal from the transmission circuit unit input from the terminal 24 via the passive element unit 18. The switch circuit unit 16 is a switch circuit composed of transistors, and is connected to the amplifier circuit unit 21. A stop signal from the control circuit unit is input to the terminal 25.

  A stop signal from the control circuit unit input to the terminal 25 turns on the transistor of the switch circuit unit 16. Then, the base of the transistor constituting the amplifier circuit unit 21 connected to the passive element unit 18 including a resistance element, a capacitor, and a diode is connected to the ground 19, and the amplifier circuit unit 21 stops the amplification operation. When the amplification operation of the amplifier circuit unit 21 is stopped, the operation of the transformer drive circuit unit 11 is also stopped and the discharge tube is stopped.

  In the fourth embodiment, as in the first embodiment, since the turn-off signal can be set for each of the plurality of inverter units 20 arranged, any discharge tube can be turned off at any timing. Further, since the discharge tube is lit by the drive signal of one transmission circuit unit, it is not necessary to synchronize the lighting of each discharge tube, so that it is difficult to generate a feedback signal. Can be used as a transformer. Further, in the fourth embodiment, as in the first embodiment, only one transmitting circuit unit is sufficient, and the discharge tube lighting device is simple in circuit configuration and easy to control.

  As described above, according to the present invention, it is possible to provide a discharge tube lighting device that achieves synchronization without arranging a base winding in a transformer, can easily control discharge of the discharge tube, and achieves power saving and space saving. It becomes.

  The discharge tube lighting device according to the present invention can be used not only as an inverter device for lighting a backlight of a liquid crystal display device but also widely used as a power supply device in various high voltage generators.

The circuit diagram of the conventional discharge tube lighting device. 1 is a block diagram of a discharge tube lighting device according to Embodiment 1. FIG. FIG. 6 is a block diagram of a discharge tube lighting device according to a second embodiment. FIG. 6 is a block diagram of a discharge tube lighting device according to a third embodiment. FIG. 6 is a block diagram of a discharge tube lighting device according to a fourth embodiment. 6 is a circuit diagram of a discharge tube lighting device according to Embodiment 4. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cold cathode tube 2 Transmitter circuit part 3, 4, 22 Transformer 5, 6 Switch 7 Base winding 11 Transformer drive circuit part 12 Transformer 13 Discharge tube 14, 20 Inverter unit 15 Transmitter circuit part 16 Switch circuit part 17 Light-off control circuit part 18 Passive element section 19 Ground 21 Amplifying circuit section 23 Output terminals 24, 25, 26, 27 terminals

Claims (3)

  An oscillation circuit unit that outputs a drive signal, a plurality of inverter units connected to the oscillation circuit unit, a discharge tube that is lit by being connected to the inverter unit, an extinction control circuit unit that outputs an extinction signal, and the extinction control A circuit unit and a switch circuit unit connected between the inverter units, wherein the inverter unit outputs a driving voltage in accordance with the driving signal, and boosts the driving voltage. The discharge tube is turned on by the boosted drive voltage output from the transformer, and the turn-off control circuit unit is preselected from the plurality of inverter units. The extinguishing signal is output to the switch circuit unit connected to the inverter unit, and the switch circuit unit is operated in advance according to the extinguishing signal. Discharge tube lighting apparatus characterized by turning off the discharge tube by the operation of the transformer driving circuit of the inverter unit is stopped.   An oscillation circuit unit that outputs a drive signal, a plurality of inverter units connected to the oscillation circuit unit, a discharge tube that is lit by being connected to the inverter unit, an extinction control circuit unit that outputs an extinction signal, and the extinction control A circuit unit and a switch circuit unit connected between each inverter unit, the inverter unit amplifying the drive signal and outputting an amplified signal, and according to the amplified signal A transformer driving circuit unit that outputs a driving voltage and a transformer that boosts the driving voltage and outputs the driving voltage to the discharge tube. The discharge tube is lit by the boosted driving voltage output from the transformer. The extinguishing control circuit unit transmits the extinguishing signal to the switch circuit unit connected to an inverter unit selected in advance from the plurality of inverter units. Outputs, the switch circuit is a discharge tube lighting apparatus characterized by turning off the discharge tube by stopping the operation of the amplification circuit in the inverter unit in response to the OFF signal.   The inverter unit is connected to the oscillation circuit unit via the switch circuit unit, and the switch circuit unit cuts off or connects the drive signal input to the inverter unit according to the turn-off signal to ground. 3. The discharge tube lighting device according to claim 1, wherein the discharge tube lighting device is connected and arranged.

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