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WO2013038795A1 - Circuit électrique, dispositif d'éclairage, et dispositif d'affichage d'image - Google Patents

Circuit électrique, dispositif d'éclairage, et dispositif d'affichage d'image Download PDF

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Publication number
WO2013038795A1
WO2013038795A1 PCT/JP2012/068018 JP2012068018W WO2013038795A1 WO 2013038795 A1 WO2013038795 A1 WO 2013038795A1 JP 2012068018 W JP2012068018 W JP 2012068018W WO 2013038795 A1 WO2013038795 A1 WO 2013038795A1
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Prior art keywords
circuit
voltage
power supply
output
smoothing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/JP2012/068018
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English (en)
Japanese (ja)
Inventor
敦幸 田中
山本　智彦
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Sharp Corp
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Sharp Corp
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Publication of WO2013038795A1 publication Critical patent/WO2013038795A1/fr
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/40—Details of LED load circuits
    • H05B45/44—Details of LED load circuits with an active control inside an LED matrix
    • H05B45/48—Details of LED load circuits with an active control inside an LED matrix having LEDs organised in strings and incorporating parallel shunting devices
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/32—Pulse-control circuits
    • H05B45/325—Pulse-width modulation [PWM]
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/37—Converter circuits
    • H05B45/3725—Switched mode power supply [SMPS]
    • H05B45/385—Switched mode power supply [SMPS] using flyback topology
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0003—Details of control, feedback or regulation circuits
    • H02M1/0032—Control circuits allowing low power mode operation, e.g. in standby mode
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
    • Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Definitions

  • the present invention relates to a power supply circuit that obtains direct current from alternating current.
  • the present invention also relates to an illumination device including a power supply circuit and an image display device.
  • LEDs light-emitting diodes
  • LEDs that can be driven with lower power consumption than incandescent bulbs and fluorescent lamps have been used as light sources for backlights of liquid crystal displays and lighting devices.
  • LEDs are advantageous in that they are small in size and strong in impact resistance, and there is no fear of ball breakage.
  • an AC power source typified by a household power source is generally used.
  • the LED is a DC drive element.
  • various power supply circuits that convert AC power into DC have been proposed.
  • Patent Document 1 includes a switching unit that switches ON / OFF of a bypass path that bypasses the next-stage LED block based on the energization amount of the LED block composed of a plurality of light-emitting diodes.
  • a light emitting diode drive circuit is disclosed.
  • Japanese Patent Publication Japanese Patent Laid-Open No. 2011-040701 (published on February 24, 2011)”
  • FIG. 8 is a circuit diagram showing an example of a conventionally used power supply circuit.
  • the power supply circuit includes an AC power supply 110 that supplies an AC voltage, a rectifier circuit 120 that rectifies the AC power supply to obtain a pulsating voltage, a smoothing circuit 130 that smoothes the pulsating voltage, and is smoothed.
  • a high-frequency transformer circuit 140 that converts the value of the pulsating current voltage, a rectifying and smoothing circuit 150 that obtains a DC voltage from the voltage-converted pulsating voltage, and a stabilization circuit 160 that stabilizes the DC voltage output from the power supply circuit. It has. As a result, the power supply circuit generates a DC voltage from the AC voltage.
  • heat loss occurs in each of the rectifier circuit 120, the smoothing circuit 130, the high-frequency transformer circuit 140, the rectifying and smoothing circuit 150, and the stabilization circuit 160.
  • the stabilization circuit 160 Conventionally, in order to obtain a DC voltage from an AC voltage as described above, a large number of circuits are required, and heat loss occurs in each of the circuits, resulting in a decrease in power supply efficiency.
  • the present invention has been made in view of the above-described problems, and a main object of the present invention is to provide a power supply circuit that can suppress generation of heat loss and improve power supply efficiency.
  • a power supply circuit includes a rectifier circuit that generates a pulsating voltage by rectifying an AC voltage, and a DC voltage generated from the pulsating voltage generated by the rectifying circuit.
  • a first output circuit that outputs a DC voltage generated by the smoothing circuit; a second output circuit that outputs a pulsating voltage generated by the rectifier circuit; A switch for switching between the first output circuit and the second output circuit is provided.
  • the power supply circuit switches between the first output circuit and the second output circuit by the switch, so that the voltage output from the power supply circuit is a DC voltage or a pulsating voltage. Switch to.
  • the power efficiency is reduced due to power loss caused by heat generated in each circuit included in the power circuit, such as the rectifier circuit and the smoothing circuit. It will decline.
  • the loss that occurs when the pulsating voltage is obtained is only the loss in the rectifier circuit, whereas the loss that occurs when the DC voltage is obtained is the loss that occurs in the rectifier circuit and the smoothing circuit. Will be included.
  • the power supply circuit can eliminate the loss due to the smoothing circuit by switching the output to the pulsating voltage.
  • the power supply circuit outputs a DC voltage when a DC voltage is required, and occurs in the power supply circuit when a DC voltage is not required (for example, when reduction of power consumption is prioritized). Loss can be suppressed and power supply efficiency can be improved.
  • a power supply circuit is generated by a rectifying and smoothing circuit that generates a pulsating voltage by rectifying and smoothing an AC voltage, and the rectifying and smoothing circuit.
  • a first output circuit that outputs a DC voltage generated by the smoothing circuit, and a pulsating voltage generated by the rectifying and smoothing circuit; And a switch that switches between the first output circuit and the second output circuit.
  • the power supply circuit switches between the first output circuit and the second output circuit by the switch, so that the voltage output from the power supply circuit is a DC voltage or a pulsating voltage. Switch to.
  • the power supply is caused by power loss caused by heat generated in each circuit included in the power supply circuit, such as the rectifying and smoothing circuit and the smoothing circuit. Efficiency will decrease.
  • the loss that occurs when the pulsating voltage is obtained is only the loss in the rectifier circuit, whereas the loss that occurs when the DC voltage is obtained is the loss that occurs in the rectifier circuit and the smoothing circuit. Will be included.
  • the power supply circuit can eliminate the loss due to the smoothing circuit by switching the output to the pulsating voltage.
  • the power supply circuit outputs a DC voltage when a DC voltage is required, and occurs in the power supply circuit when a DC voltage is not required (for example, when reduction of power consumption is prioritized). Loss can be suppressed and power supply efficiency can be improved.
  • the power supply circuit outputs a pulsating voltage obtained by rectifying and smoothing the AC voltage from the second output circuit, it is more direct current than when outputting a pulsating voltage obtained by only rectifying the AC voltage. A pulsating voltage close to the voltage can be output.
  • an illumination device includes the above-described power supply circuit and a light source, and the light source is driven by the power supply circuit.
  • the lighting device drives the light source with a DC voltage when a DC voltage is required to drive the light source, and generates a loss in the power supply circuit when a DC voltage is not required. It can suppress and can improve power supply efficiency.
  • An image display device including the above-described illumination device as a backlight device for a display panel is also included in the scope of the present invention.
  • the power supply circuit includes a rectifying circuit that generates a pulsating voltage by rectifying an AC voltage, and a smoothing circuit that generates a DC voltage from the pulsating voltage generated by the rectifying circuit.
  • a first output circuit that outputs the generated DC voltage; a second output circuit that outputs a pulsating voltage generated in the rectifier circuit; the first output circuit and the second output circuit; And a switch for switching.
  • the power supply circuit outputs a DC voltage when a DC voltage output is required, and suppresses a loss generated in the power supply circuit when a DC voltage is not required, thereby improving the power efficiency. Can be improved.
  • FIG. 1 It is a figure which shows the waveform of the voltage in each circuit with which the power supply circuit which concerns on other embodiment of this invention is equipped, (a) shows the waveform of the alternating voltage in an alternating current power supply, (b) is output from a 2nd output circuit. (C) shows the waveform of the DC voltage output from the first output circuit.
  • FIG. It is a circuit diagram which shows an example of a structure of the power supply circuit in a prior art.
  • a lighting device including a power supply circuit is provided in a television receiver (image display device) (hereinafter also referred to as a television), and a backlight (light source) of a liquid crystal display panel provided in the television is provided.
  • a television receiver image display device
  • a backlight (light source) of a liquid crystal display panel provided in the television is provided.
  • the display panel functions as a backlight driving circuit for driving the TV (in other words, the television includes a lighting device including a power supply circuit as a backlight device for a display panel).
  • FIG. 2 is a block diagram illustrating an outline of the television 100 according to the present embodiment.
  • the television 100 includes a power supply circuit 1 and a display device 50.
  • the power supply circuit 1 includes an AC power supply 10, a first rectifier circuit (rectifier circuit) 20, a first output circuit 30, a second output circuit 40, and a switch 45. The details of the power supply circuit 1 will be described later with different drawings.
  • the display device 50 includes a liquid crystal drive circuit 51, a liquid crystal display panel 52, and an LED group (backlight) 53.
  • the liquid crystal driving circuit 51 is supplied with a DC voltage generated from a pulsating voltage generated in the first rectifier circuit 20 described later, and drives the liquid crystal display panel 52 to display an image.
  • the liquid crystal display panel 52 is driven by the liquid crystal driving circuit 51 to display an image.
  • the LED group 53 is a backlight of the liquid crystal display panel 52 and has a plurality of light emitting diodes (LEDs).
  • the LED group 53 is driven by a DC voltage supplied from the first output circuit 30 included in the power supply circuit 1 or a pulsating voltage supplied from the second output circuit 40.
  • FIG. 1 is a circuit diagram showing a configuration of a power supply circuit 1 according to the present embodiment.
  • the power supply circuit 1 includes an AC power supply 10, a first rectifier circuit (rectifier circuit) 20, a first output circuit 30, a second output circuit 40, and an LED group 53. It has.
  • the first rectifier circuit 20 is a circuit that generates a pulsating voltage by full-wave rectifying the AC voltage supplied from the AC power supply 10. As shown in FIG. 1, the first rectifier circuit 20 has four diodes 21 to 24, and the diodes 21 to 24 constitute a so-called diode bridge circuit.
  • the cathode terminal of the diode 21 is connected to one end of the AC power supply 10, the anode terminal is connected to the anode terminal of the diode 23, and the cathode terminal of the diode 23 is connected to the other end of the AC power supply 10.
  • the anode terminal of the diode 22 is connected to the cathode terminal of the diode 21, the cathode terminal is connected to the cathode terminal of the diode 24, and the anode terminal of the diode 23 is connected to the cathode terminal of the diode 23.
  • the cathode terminals of the diode 22 and the diode 24 are connected to an input terminal of a switch 45 described later.
  • the first output circuit 30 is a circuit that outputs a DC voltage generated from the pulsating voltage generated in the first rectifier circuit 20, and outputs a DC voltage to the LED group 53 in FIG. 1.
  • the LED group 53 is driven by a DC voltage supplied from the first output circuit 30.
  • the first output circuit 30 includes a first smoothing circuit (smoothing circuit) 31, a high-frequency transformer circuit 32, a second rectifier circuit 33, a second smoothing circuit 34, and a stabilization circuit. 35.
  • the first smoothing circuit 31 is a circuit that smoothes the pulsating voltage generated in the first rectifier circuit 20.
  • the first smoothing circuit 31 has a capacitor 311 as shown in FIG. One end of the capacitor 311 is connected to one end of the output terminal of the switch 45, and the other end is connected to the anode terminals of the diode 21 and the diode 23, and one end of the input terminal of the switching circuit 353 provided in the stabilization circuit 35 described later. It is connected.
  • the high-frequency transformer circuit 32 is a circuit that changes the smoothed pulsating voltage to a desired (necessary) voltage. As shown in FIG. 1, the high-frequency transformer circuit 32 includes a primary coil 321 and a secondary coil 322. One end of the primary coil 321 is connected to one end of the capacitor 311, and the other end is connected to the output terminal of the switching circuit 353.
  • the second rectifier circuit 33 is a circuit that rectifies the voltage converted in the high-frequency transformer circuit 32 and brings it close to a DC voltage.
  • the second rectifier circuit includes a diode 331 and a diode 332.
  • the anode terminal of the diode 331 is connected to one end of the secondary coil 322, the cathode terminal is connected to the cathode terminal of the diode 332, and the anode terminal of the diode 332 is connected to the other end of the secondary coil 322.
  • the second smoothing circuit 34 is a circuit that further smoothes the voltage rectified in the second rectifier circuit 33 to obtain a DC voltage.
  • the second smoothing circuit 34 includes a choke coil 341 and a capacitor 342. One end of the choke coil 341 is connected to the diode 331 and the cathode terminal of the diode 332, the other end is connected to one end of the capacitor 342, and the other end of the capacitor 342 is connected to the anode terminal of the diode 332.
  • the stabilization circuit 35 is a feedback circuit that operates so that the DC output voltage is always a constant value.
  • the stabilization circuit 35 includes a detection circuit 351, a pulse width conversion circuit 352, and a switching circuit 353.
  • the input terminal of the detection circuit 351 is connected to one end of the capacitor 342 and the anode terminal of the LED group 53, and the output terminal is connected to the input terminal of the pulse width conversion circuit 352.
  • the input terminal of the pulse width conversion circuit 352 is connected to the output terminal of the detection circuit 351, and the output terminal is connected to the other end of the input terminal of the switching circuit 353.
  • One end of the input terminal of the switching circuit 353 is connected to the other end of the capacitor 311, the other end of the input terminal is connected to the output terminal of the pulse width conversion circuit 352, and the output terminal is connected to the other end of the primary coil 321. It is connected.
  • the detection circuit 351 detects the output voltage of the first output circuit 30 and supplies the detection result to the pulse width conversion circuit 352.
  • the pulse width conversion circuit 352 generates a pulse signal that controls ON / OFF in the switching circuit 353 based on the detection result supplied from the detection circuit 351.
  • the switching circuit 353 switches ON / OFF of the primary coil 321 according to the pulse signal supplied from the pulse width conversion circuit 352.
  • the switching circuit 353 can be configured by a transistor, a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), or the like.
  • the high-frequency transformer circuit 32, the second rectifier circuit 33, the second smoothing circuit 34, and the stabilization circuit 35 constitute a voltage changing circuit that changes the value of the output DC voltage. Specifically, the pulsating voltage whose value has been converted by the high-frequency transformer circuit 32 and the stabilization circuit 35 is rectified and smoothed by the second rectifier circuit 33 and the second smoothing circuit 34 to output a direct current. The voltage value has been changed.
  • the first smoothing circuit 31 and the second smoothing circuit 34 constitute a smoothing circuit, but the present invention is not limited to this.
  • the smoothing circuit may be configured by only the first smoothing circuit 31, or the smoothing circuit may be configured by only the second smoothing circuit 34.
  • the second output circuit 40 is a circuit that directly outputs the pulsating voltage generated in the first rectifier circuit 20.
  • the pulsating voltage is directly output to the LED group 53.
  • the 2nd output circuit 40 can mention conducting wire as the simplest structure.
  • One end of the second output circuit 40 is connected to the other end of the output terminal of the switch 45, and the other end is connected to the anode terminal of the LED group 53.
  • the second output circuit 40 is a conductive wire
  • the present invention is not limited to this.
  • a configuration in which a circuit with a smaller loss than the power loss in the first output circuit 30 described later (for example, a configuration in which only the first smoothing circuit 31 is provided) may be employed.
  • the switch 45 is a circuit that switches between the first output circuit 30 and the second output circuit 40 as a circuit that outputs a voltage to the LED group 53.
  • the input terminal of the switch 45 is connected to the cathode terminals of the diode 22 and the diode 24, and one end of the output terminal is connected to one end of the capacitor 311 included in the first smoothing circuit 31 included in the first output circuit 30. The other end is connected to one end of the second output circuit 40.
  • FIG. 3 is a diagram illustrating voltage waveforms in each circuit included in the power supply circuit 1 according to the present embodiment.
  • 3A is a diagram showing a waveform of an AC voltage in the AC power supply 10
  • FIG. 3B is a pulsating voltage rectified in the first rectifier circuit 20 (that is, output from the second output circuit 40).
  • C is a diagram illustrating a waveform of a DC voltage output from the first output circuit 30.
  • the power supply circuit 1 first full-wave rectifies the AC voltage shown in FIG. 3A supplied from the AC power supply 10 into the pulsating voltage shown in FIG. In the normal mode, the pulsating voltage rectified in the first rectifier circuit 20 is supplied to the first smoothing circuit 31 included in the first output circuit 30 via the switch 45.
  • the first smoothing circuit 31 smoothes the supplied pulsating voltage and supplies the smoothed pulsating voltage to the high-frequency transformer circuit 32.
  • the high frequency transformer circuit 32 converts the voltage supplied from the first smoothing circuit 31 into a desired voltage.
  • the voltage converted in the high-frequency transformer circuit 32 is further rectified by the second rectifier circuit 33 and then smoothed by the second smoothing circuit 34 to become a DC voltage shown in FIG.
  • the DC voltage smoothed by the second smoothing circuit 34 is always kept constant by appropriately switching between conduction and interruption of the primary coil 321 in the switching circuit 353 provided in the stabilization circuit 35.
  • a DC voltage is generated from the AC voltage shown in FIG. 3A by the operation of the first output circuit 30 described above.
  • the DC voltage generated in the first output circuit 30 is supplied to the LED group 53. That is, the LED group 53 is driven by a DC voltage supplied from the first output circuit 30.
  • the power supply circuit 1 is the value of the DC voltage output in the voltage changing circuit configured by the high-frequency transformer circuit 32, the second rectifier circuit 33, the second smoothing circuit 34, and the stabilization circuit 35.
  • the value of the DC voltage output from the first output circuit 30 can be arbitrarily changed by changing. Therefore, the power supply circuit 1 can drive the LED group 53 with a DC voltage having a desired value by arbitrarily changing the value of the voltage output from the first output circuit 30 in the normal mode. That is, the power supply circuit 1 can arbitrarily change the luminous intensity of the LED group 53 in the normal mode.
  • the luminous intensity (luminance) of the LED group 53 can be increased by increasing the value of the DC voltage output from the first output circuit 30, and the luminous intensity of the LED group 53 can be decreased by decreasing the value.
  • the power supply circuit 1 first rectifies the AC voltage shown in FIG. 3A supplied from the AC power supply 10 into the pulsating voltage shown in FIG. In the power saving mode, the pulsating voltage rectified in the first rectifier circuit 20 is supplied to the second output circuit 40 via the switch 45. In other words.
  • the second output circuit 40 supplies the supplied pulsating voltage to the LED group 53 as it is. Accordingly, the LED group 53 is driven by the pulsating voltage supplied from the second output circuit 40 and shown in FIG.
  • the power efficiency conversion efficiency from the AC power source to the output voltage of the power source circuit 1
  • the power efficiency can be improved by driving the LED group 53 with the pulsating voltage.
  • the first rectifier circuit 20 the first smoothing circuit 31, the high-frequency transformer circuit 32, the second rectifier circuit 33, and the second included in the power supply circuit 1 for converting an AC voltage into a DC voltage.
  • the power supply efficiency is reduced by power loss (heat generation loss) caused by heat generated in each element included in the smoothing circuit 34 and the stabilization circuit 35.
  • the power saving mode since the circuit except the first rectifier circuit 20 is bypassed by the second output circuit 40, the first smoothing circuit 31, the high-frequency transformer circuit 32, the second rectifier circuit 33, and the second smoothing are performed. Losses that occur in the circuit 34 and the stabilization circuit 35 can be eliminated. That is, in the power saving mode, the loss generated in the power supply circuit 1 is only the loss generated in the first rectifier circuit 20. That is, when the output of the DC voltage is not required, the power supply circuit 1 can eliminate the loss due to the circuits other than the first rectifier circuit 20 by switching the output to the pulsating voltage.
  • the power supply circuit 1 can reduce the decrease in power supply efficiency and efficiently drive the LED group 53 by the power saving mode. In other words, the power supply circuit 1 suppresses loss generated in the power supply circuit 1 and improves power supply efficiency when output of a DC voltage is not necessary (for example, when reduction of power consumption is given priority). be able to.
  • the power supply circuit 1 can switch between the first output circuit 30 and the second output circuit 40 by the switch 45. That is, the power supply circuit 1 can switch between the normal mode and the power saving mode by the switch 45.
  • the power supply circuit 1 can change the luminous intensity of the LED group 53 by switching to the normal mode, and further reduces the decrease in power supply efficiency by switching to the power saving mode, and efficiently drives the LED group 53. be able to.
  • FIG. 4 is a block diagram illustrating an outline of the television 200 according to the present embodiment.
  • the television 200 includes a power supply circuit 2 and a display device 50.
  • the power supply circuit 2 includes an AC power supply 10, a rectifying / smoothing circuit 60, a first output circuit 30 ′, a second output circuit 40, and a switch 45. The details of the power supply circuit 2 will be described later with different drawings.
  • the LED group 53 is a backlight of the liquid crystal display panel 52 and has a plurality of light emitting diodes (LEDs).
  • the LED group 53 is driven by a DC voltage supplied from the first output circuit 30 ′ included in the power supply circuit 2 or a pulsating voltage supplied from the second output circuit 40.
  • FIG. 5 is a circuit diagram showing a configuration of the power supply circuit 2 according to the present embodiment.
  • the power supply circuit 2 includes an AC power supply 10, a rectifying / smoothing circuit 60, a first output circuit 30 ′, a second output circuit 40, and an LED group 53. Yes.
  • the rectifying / smoothing circuit 60 is a circuit that generates a pulsating voltage by rectifying and smoothing an AC voltage supplied from the AC power supply 10.
  • the rectifying / smoothing circuit 60 includes a first rectifying circuit 61 and a first smoothing circuit 62 as shown in FIG. 5 in order to generate a pulsating voltage.
  • the first rectifier circuit 61 is a circuit that rectifies an AC voltage supplied from the AC power supply 10.
  • the first rectifier circuit 61 includes four diodes 611 to 614 as shown in FIG.
  • the cathode terminal of the diode 611 is connected to one end of the AC power supply 10, the anode terminal is connected to the anode terminal of the diode 613, and the cathode terminal of the diode 613 is connected to the other end of the AC power supply 10.
  • the anode terminal of the diode 612 is connected to the cathode terminal of the diode 611, the cathode terminal is connected to the cathode terminal of the diode 614, and the anode terminal of the diode 613 is connected to the cathode terminal of the diode 613.
  • the cathode terminals of the diode 612 and the diode 614 are connected to one end of a capacitor 621 described later.
  • the first smoothing circuit 62 is a circuit that smoothes the voltage rectified in the first rectifier circuit 61.
  • the first smoothing circuit 62 includes a capacitor 621 as shown in FIG. One end of the capacitor 621 is connected to the cathode terminals of the diode 612 and the diode 614, and the other end is connected to the anode terminals of the diode 611 and the diode 613.
  • the rectifying / smoothing circuit 60 rectifies the AC voltage supplied from the AC power supply 10 in the first rectifying circuit 61 and smoothes it in the first smoothing circuit 62, thereby generating a pulsating voltage.
  • the first output circuit 30 ′ is a circuit that outputs a DC voltage generated from the pulsating voltage generated in the rectifying and smoothing circuit 60, and outputs a DC voltage to the LED group 53 in FIG. 5.
  • the LED group 53 is driven by a DC voltage supplied from the first output circuit 30 ′.
  • the first output circuit 30 ′ includes a high-frequency transformer circuit (voltage change circuit) 32, a second rectifier circuit 33, a second smoothing circuit (smoothing circuit) 34, and a stabilization circuit 35. It has.
  • the high frequency transformer circuit 32 is a circuit that converts (changes) the voltage supplied from the AC power supply 10 into a desired voltage. As shown in FIG. 5, the high-frequency transformer circuit 32 includes a primary coil 321 and a secondary coil 322. One end of the primary coil 321 is connected to one end of an output terminal of a switch 45 described later, and the other end is connected to an output terminal of the switching circuit 353.
  • the second output circuit 40 is a circuit that directly outputs the pulsating voltage generated in the rectifying / smoothing circuit 60.
  • the pulsating voltage is directly output to the LED group 53.
  • the 2nd output circuit 40 can mention conducting wire as the simplest structure.
  • the LED group 53 is driven by a DC voltage supplied from the second output circuit 40.
  • One end of the second output circuit 40 is connected to the other end of the output terminal of the switch 45, and the other end is connected to the anode terminal of the LED group 53.
  • the second output circuit 40 is a conductive wire
  • the present invention is not limited to this.
  • a configuration in which a circuit with a smaller loss than the power loss in the first output circuit 30 ′ described later may be employed.
  • the switch 45 is a circuit that switches between the first output circuit 30 ′ and the second output circuit 40 as a circuit that outputs a voltage to the LED group 53.
  • the input terminal of the switch 45 is connected to one end of the capacitor 621, one end of the output terminal is connected to one end of the primary coil 321 included in the high-frequency transformer circuit included in the first output circuit 30 ′, and the other end of the output terminal is the first. 2 is connected to one end of the output circuit 40.
  • FIG. 6 is a diagram illustrating voltage waveforms in each circuit included in the power supply circuit 2 according to the present embodiment.
  • 6A is a diagram showing a waveform of an AC voltage in the AC power supply 10
  • FIG. 6B is a pulsating voltage rectified and smoothed by the rectifying / smoothing circuit 60 (that is, the second output circuit).
  • (C) is a diagram illustrating a waveform of a DC voltage output from the first output circuit 30 ′.
  • the power supply circuit 2 first full-wave rectifies the AC voltage shown in FIG. 6A supplied from the AC power supply 10 in the first rectifier circuit 61 provided in the rectifying / smoothing circuit 60.
  • the voltage rectified in the first rectifier circuit 61 is supplied to the first smoothing circuit 62.
  • the first smoothing circuit 62 smoothes the supplied voltage.
  • the rectifying / smoothing circuit 60 rectifies and smoothes the first rectifying circuit 61 and the first smoothing circuit 62 to generate a pulsating voltage shown in FIG.
  • the pulsating voltage generated in the rectifying / smoothing circuit 60 is supplied to the high-frequency transformer circuit 32 included in the first output circuit 30 ′ via the switch 45.
  • the high-frequency transformer circuit 32 converts the pulsating voltage supplied from the rectifying / smoothing circuit 60 into a desired voltage.
  • the voltage converted in the high-frequency transformer circuit 32 is further rectified by the second rectifier circuit 33 and then smoothed by the second smoothing circuit 34 to become a DC voltage shown in FIG. 6C.
  • the DC voltage smoothed by the second smoothing circuit 34 is always kept constant by appropriately switching between conduction and interruption of the primary coil 321 in the switching circuit 353 provided in the stabilization circuit 35.
  • a DC voltage is generated from the AC voltage shown in FIG. 6A by the operation of the first output circuit 30 'described above.
  • the DC voltage generated in the first output circuit 30 ′ is supplied to the LED group 53. That is, the LED group 53 is driven by the DC voltage shown in FIG. 6C supplied from the first output circuit 30 '.
  • the power supply circuit 2 can arbitrarily change the value of the voltage output from the first output circuit 30 ′ by changing a desired voltage obtained in the high-frequency transformer circuit 32. Therefore, the power supply circuit 2 can drive the LED group 53 with a DC voltage having a desired value by arbitrarily changing the value of the voltage output from the first output circuit 30 ′ in the normal mode. That is, the power supply circuit 2 can change the luminous intensity of the LED group 53 in the normal mode.
  • the luminous intensity (luminance) of the LED group 53 can be increased by increasing the value of the DC voltage output from the first output circuit 30 ′, and the luminous intensity of the LED group 53 can be decreased by decreasing the value. .
  • the power supply circuit 2 first rectifies the AC voltage shown in FIG. 6A supplied from the AC power supply 10 in the first rectifier circuit 61 provided in the rectifying and smoothing circuit 60.
  • the voltage rectified in the first rectifier circuit 61 is supplied to the first smoothing circuit 62.
  • the first smoothing circuit 62 smoothes the supplied voltage.
  • the rectifying / smoothing circuit 60 rectifies and smoothes the first rectifying circuit 61 and the first smoothing circuit 62 to generate a pulsating voltage shown in FIG.
  • the pulsating voltage rectified in the rectifying / smoothing circuit 60 is supplied to the second output circuit 40 via the switch 45.
  • the second output circuit 40 supplies the supplied pulsating voltage to the LED group 53 as it is.
  • the LED group 53 is driven by the pulsating voltage supplied from the second output circuit 40 and shown in FIG.
  • the power efficiency can be improved by driving the LED group 53 with the pulsating voltage.
  • the power supply efficiency is reduced due to power loss (heat generation loss) caused by heat generated in each element included in the stabilization circuit 35.
  • the power supply circuit 2 can eliminate the loss due to the circuits other than the rectifying and smoothing circuit 60 by switching the output to the pulsating voltage.
  • the power supply circuit 2 can reduce the decrease in power supply efficiency and efficiently drive the LED group 53 by the power saving mode. In other words, the power supply circuit 2 suppresses the loss generated in the power supply circuit 2 and improves the power supply efficiency when the output of the DC voltage is not necessary (for example, when reduction of power consumption is given priority). be able to.
  • the power supply circuit 2 can switch between the first output circuit 30 ′ and the second output circuit 40 by the switch 45. That is, the power supply circuit 2 can switch between the normal mode and the power saving mode by the switch 45.
  • the power supply circuit 2 can change the luminous intensity of the LED group 53 by switching to the normal mode, and further reduces the decrease in power supply efficiency by switching to the power saving mode, thereby driving the LED group 53 efficiently. Can do.
  • the power supply circuit 2 outputs the pulsating voltage obtained by rectifying and smoothing the AC voltage from the second output circuit 40, compared with the case where the pulsating voltage obtained by only rectifying the AC voltage is output. A pulsating voltage close to a DC voltage can be output.
  • a power supply circuit includes a rectifier circuit that generates a pulsating voltage by rectifying an AC voltage, and a smoothing that generates a DC voltage from the pulsating voltage generated by the rectifier circuit.
  • a first output circuit that outputs a DC voltage generated by the smoothing circuit, a second output circuit that outputs a pulsating voltage generated by the rectifier circuit, and the first output circuit.
  • a switch for switching between the output circuit and the second output circuit.
  • the power supply circuit switches between the first output circuit and the second output circuit by the switch, so that the voltage output from the power supply circuit is a DC voltage or a pulsating voltage. Switch to.
  • the power efficiency is reduced due to power loss caused by heat generated in each circuit included in the power circuit, such as the rectifier circuit and the smoothing circuit. It will decline.
  • the loss that occurs when the pulsating voltage is obtained is only the loss in the rectifier circuit, whereas the loss that occurs when the DC voltage is obtained is the loss that occurs in the rectifier circuit and the smoothing circuit. Will be included.
  • the power supply circuit can eliminate the loss due to the smoothing circuit by switching the output to the pulsating voltage.
  • the power supply circuit outputs a DC voltage when a DC voltage is required, and occurs in the power supply circuit when a DC voltage is not required (for example, when reduction of power consumption is prioritized). Loss can be suppressed and power supply efficiency can be improved.
  • a power supply circuit includes a rectifying / smoothing circuit that generates a pulsating voltage by rectifying and smoothing an AC voltage, and a pulse generated by the rectifying / smoothing circuit.
  • a first output circuit that outputs a DC voltage generated by the smoothing circuit, and a pulsating voltage generated by the rectifying and smoothing circuit;
  • a second output circuit and a switch for switching between the first output circuit and the second output circuit are provided.
  • the power supply circuit switches between the first output circuit and the second output circuit by the switch, so that the voltage output from the power supply circuit is a DC voltage or a pulsating voltage. Switch to.
  • the power supply is caused by power loss caused by heat generated in each circuit included in the power supply circuit, such as the rectifying and smoothing circuit and the smoothing circuit. Efficiency will decrease.
  • the loss that occurs when the pulsating voltage is obtained is only the loss in the rectifier circuit, whereas the loss that occurs when the DC voltage is obtained is the loss that occurs in the rectifier circuit and the smoothing circuit. Will be included.
  • the power supply circuit can eliminate the loss due to the smoothing circuit by switching the output to the pulsating voltage.
  • the power supply circuit outputs a DC voltage when a DC voltage is required, and occurs in the power supply circuit when a DC voltage is not required (for example, when reduction of power consumption is prioritized). Loss can be suppressed and power supply efficiency can be improved.
  • the power supply circuit outputs a pulsating voltage obtained by rectifying and smoothing the AC voltage from the second output circuit, it is more direct current than when outputting a pulsating voltage obtained by only rectifying the AC voltage. A pulsating voltage close to the voltage can be output.
  • the first output circuit includes a voltage changing circuit that changes a value of a DC voltage to be output.
  • the power supply circuit can change the value of the DC voltage output from the first output circuit.
  • the power supply circuit can drive a device connected to the power supply circuit with a DC voltage having a desired value.
  • the luminous intensity (brightness) is increased by increasing the direct current voltage output from the first output circuit, and the first output circuit The luminous intensity can be lowered by reducing the output DC voltage.
  • the power supply circuit can change the value of the output voltage by switching the output circuit to the first output circuit, and the power supply efficiency can be improved by switching to the second output circuit.
  • an illumination device includes the above-described power supply circuit and a light source, and the light source is driven by the power supply circuit.
  • the lighting device drives the light source with a DC voltage when a DC voltage is required to drive the light source, and generates a loss in the power supply circuit when a DC voltage is not required. It can suppress and can improve power supply efficiency.
  • the light source is preferably a light emitting diode.
  • the lighting device when the light emitting diode is driven, when the reduction of power consumption is required rather than the driving by the DC voltage, the lighting device suppresses the loss generated in the power supply circuit, and the power efficiency Can be improved.
  • the lighting circuit can change the value of the output voltage by switching the output circuit of the power supply circuit to the first output circuit, and can change the luminous intensity of the light emitting diode. Furthermore, the power supply efficiency can be improved by switching the output circuit of the power supply circuit to the second output circuit.
  • An image display device including the above-described illumination device as a backlight device for a display panel is also included in the scope of the present invention.
  • the present invention can be suitably used as a power supply circuit for driving a lighting device and a backlight of a liquid crystal display.

Landscapes

  • Dc-Dc Converters (AREA)
  • Circuit Arrangement For Electric Light Sources In General (AREA)

Abstract

La présente invention concerne un circuit électrique (1) qui comprend un premier circuit redresseur (20) qui génère une tension pulsatoire à partir d'une tension alternative, un premier circuit de sortie (30) qui produit une tension continue générée à partir de la tension pulsatoire, un second circuit de sortie (40) qui produit la tension pulsatoire, et un commutateur pour commuter entre le premier circuit de sortie (30) et le second circuit de sortie (40).
PCT/JP2012/068018 2011-09-13 2012-07-13 Circuit électrique, dispositif d'éclairage, et dispositif d'affichage d'image Ceased WO2013038795A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2011-199778 2011-09-13
JP2011199778 2011-09-13

Publications (1)

Publication Number Publication Date
WO2013038795A1 true WO2013038795A1 (fr) 2013-03-21

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH1141825A (ja) * 1997-07-14 1999-02-12 Victor Co Of Japan Ltd 電源切替装置
JPH11136858A (ja) * 1997-10-28 1999-05-21 Konica Corp 省電力モードを有する機器の電源装置、省電力制御装置及び画像形成装置
JP2005020992A (ja) * 2003-06-06 2005-01-20 Sony Corp 電源装置
JP2005252635A (ja) * 2004-03-04 2005-09-15 Alps Electric Co Ltd 送受信装置
JP2008310963A (ja) * 2007-06-12 2008-12-25 Toshiba Lighting & Technology Corp Ｌｅｄ点灯装置およびｌｅｄ照明器具
JP2011040701A (ja) * 2009-07-14 2011-02-24 Nichia Corp 発光ダイオード駆動回路及び発光ダイオードの点灯制御方法

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH1141825A (ja) * 1997-07-14 1999-02-12 Victor Co Of Japan Ltd 電源切替装置
JPH11136858A (ja) * 1997-10-28 1999-05-21 Konica Corp 省電力モードを有する機器の電源装置、省電力制御装置及び画像形成装置
JP2005020992A (ja) * 2003-06-06 2005-01-20 Sony Corp 電源装置
JP2005252635A (ja) * 2004-03-04 2005-09-15 Alps Electric Co Ltd 送受信装置
JP2008310963A (ja) * 2007-06-12 2008-12-25 Toshiba Lighting & Technology Corp Ｌｅｄ点灯装置およびｌｅｄ照明器具
JP2011040701A (ja) * 2009-07-14 2011-02-24 Nichia Corp 発光ダイオード駆動回路及び発光ダイオードの点灯制御方法

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