Power supply apparatus and display apparatus

• US 20060192501A1
• Filed: 12/03/2004
• Published: 08/31/2006
• Est. Priority Date: 05/17/2004
• Status: Active Grant

• Current Assignee: Saturn Licensing LLC (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Oyama, Yoshiki, Kanoi, Nobuhiko, Ogura, Noburo
• Granted Patent: US 7,764,022 B2
• Time in Patent Office: Days
• US Class Current: 315/308
• CPC Class Codes: H02M 1/007 Plural converter units in cascade push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826
• CPC Class Codes: H02M 1/008 Plural converter units for generating at two or more independent and non-parallel outputs, e.g. systems with plural point of load switching regulators
• CPC Class Codes: H02M 7/53803 with automatic control of output voltage or current
• CPC Class Codes: H05B 41/2827 using specially adapted components in the load circuit, e.g. feed-back transformers, piezoelectric transformers; using specially adapted load circuit configurations
• CPC Class Codes: H05B 45/24 using electrical feedback from LEDs or from LED modules
• CPC Class Codes: H05B 45/37 Converter circuits
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]
• CPC Class Codes: H05B 45/38 using boost topology
• CPC Class Codes: H05B 45/382 with galvanic isolation between input and output

Abstract

A liquid crystal display apparatus is capable of reducing a power loss incurred by a power-supply section in a process of generating a power-supply voltage for driving a backlight section. In the configuration of the power-supply section, a main power-supply circuit and an inverter circuit (or a DC-DC converter) are connected to an input-voltage generation unit in parallel to each other, which is used for rectifying and smoothing the commercial alternative current power. The main power-supply circuit and the inverter circuit (or the DC-DC converter) each include an isolation transformer including a primary-side winding not isolated from the commercial alternative current power and a secondary winding provided on the secondary side. The direct current input voltage is supplied to the primary side to be subjected to a power conversion process to generate an output voltage on the secondary side of the isolation transformer. Thus, the number of power conversion process stages for supplying power to the backlight section connected to the inverter circuit (or the DC-DC converter) is reduced by 1. As a result, the power loss incurred by the power-supply section can be reduced to a value smaller than that of the conventional one.

Claims

1. A power-supply apparatus comprising:

an input-voltage generation section for generating a direct current input voltage from an input alternative current;

a first power conversion section including a primary side for receiving said direct current input voltage as well as a secondary side isolated from said primary side and used for generating a direct current power-supply voltage to be supplied to a predetermined load as a result of a DC-DC power conversion process carried out on said direct current input voltage; and

a second power conversion section including a primary side for receiving said direct current input voltage as well as a secondary side isolated from said primary side and used for generating a power-supply voltage to be supplied to a backlight section of a display apparatus.

2. The power-supply apparatus according to claim 1, wherein said input-voltage generation section is a rectification/smoothing circuit, which:

comprises diodes for rectifying said alternative current and a capacitor for smoothing a rectified output of said diodes, and

generates said direct current input voltage as a voltage appearing between terminals of said capacitor.

3. The power-supply apparatus according to claim 1 wherein said input-voltage generation section is a power-factor improvement converter for generating a stabilized direct current output voltage as said direct current input voltage.

4. The power-supply apparatus according to claim 1, further including a detection section for detecting a voltage or current supplied to said backlight section and a feedback section for feeding back a detection signal generated by said detection section, wherein:

said second power conversion section has a switching device for switching said direct current input voltage and a driving section for driving said switching device; and

said feedback section isolates said detection signal and feeds back said isolated detection signal to said driving section in order to stabilize said power-supply voltage or current.

5. The power-supply apparatus according to claim 1, including said display apparatus comprising a plurality of said backlight sections, wherein as many said second power conversion sections as said backlight sections are provided.

6. The power-supply apparatus according to claim 4, wherein:

a fluorescent tube is employed as said backlight section; and

said second power conversion section carries out power conversion process by performing a DC-AC power conversion process to generate an alternative current power-supply voltage to be supplied to said fluorescent tube.

7. The power-supply apparatus according to claim 4, wherein:

a light-emitting diode is employed as said backlight section; and

said second power conversion section carries out power conversion process by performing a DC-DC power conversion process to generate a direct current power-supply voltage to be supplied to said light-emitting diode.

8. A display apparatus having a backlight section and a load other than said backlight section, said display apparatus comprising:

an input-voltage generation section for generating a direct current input voltage from an alternative current;

a first power conversion section including a primary side for receiving said direct current input voltage as well as a secondary side isolated from said primary side and used for generating a direct current power-supply voltage to be supplied to said load as a result of a DC-DC power conversion process carried out on said direct current input voltage;

a second power conversion section including a primary side for receiving said direct current input voltage as well as a secondary side isolated from said primary side and used for generating a power-supply voltage to be supplied to said backlight section; and

a display section for displaying a picture by using said backlight section.

9. The power-supply apparatus according to claim 8 wherein a plurality of said backlight sections is employed as a light source of said display section and as many said second power conversion sections as said backlight sections are provided.

10. The power-supply apparatus according to claim 8 wherein:

a fluorescent tube is employed as said backlight section; and

said second power conversion section carries out power conversion process by performing a DC-AC power conversion process to generate an alternative current as said power-supply voltage to be supplied to said fluorescent tube.

11. The power-supply apparatus according to claim 8 wherein:

a fluorescent tube is employed as said backlight section; and

said second power conversion section carries out power conversion process by performing a DC-DC power conversion process to generate a direct current as said power-supply voltage to be supplied to said light-emitting diode.