JP2003152224A - High-efficiency led driving system - Google Patents

High-efficiency led driving system

Info

Publication number
JP2003152224A
JP2003152224A JP2001351464A JP2001351464A JP2003152224A JP 2003152224 A JP2003152224 A JP 2003152224A JP 2001351464 A JP2001351464 A JP 2001351464A JP 2001351464 A JP2001351464 A JP 2001351464A JP 2003152224 A JP2003152224 A JP 2003152224A
Authority
JP
Japan
Prior art keywords
led
voltage
circuit
output voltage
booster circuit
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.)
Pending
Application number
JP2001351464A
Other languages
Japanese (ja)
Inventor
Takeshi Tanaka
武 田中
Original Assignee
Matsushita Electric Ind Co Ltd
松下電器産業株式会社
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Matsushita Electric Ind Co Ltd, 松下電器産業株式会社 filed Critical Matsushita Electric Ind Co Ltd
Priority to JP2001351464A priority Critical patent/JP2003152224A/en
Publication of JP2003152224A publication Critical patent/JP2003152224A/en
Pending legal-status Critical Current

Links

Abstract

(57) [Summary] [PROBLEMS] When a white LED or the like is driven by a booster circuit,
By detecting the current flowing through the LED and controlling the output voltage of the booster circuit so that the output voltage becomes a constant value, it is not necessary to set the output voltage with the standard margin of the forward voltage VF of the LED, which is conventionally required. As a result, the power corresponding to the product of the margin voltage and the current flowing through the LED can be reduced, and the efficiency can be increased. An LED current detection circuit is provided to compare a current value with a reference current value. This comparison output is input to an output voltage control circuit of a booster circuit for driving an LED, and is controlled so as to match a reference voltage value. The voltage control circuit of the booster circuit is VCO
Although there are various circuits such as a PWM and a PWM, the basic concept is the same in any of the systems.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LED driving system. 2. Description of the Related Art At present, portable devices such as portable telephones have been widely used. However, due to demands such as extension of standby time and continuous use time, and consideration for the environment, efforts have been made to use power supplies with high efficiency. ing. Various devices have been devised for highly efficient driving of light emitting devices such as LEDs. [0003] In recent years, in particular, white LEDs have been frequently used as backlight light sources for liquid crystal display devices because of the necessity of color display. Since the white LED has a large forward voltage VF,
Devices using a single cell such as a lithium-ion battery such as a mobile phone require a booster circuit. The booster circuit includes a charge pump, a DC / DC converter using an inductor, and the like, and the use of a DC / DC converter with emphasis on efficiency is increasing. A conventional white LED driving circuit will be described below with reference to FIG. In FIG. 3, reference numeral 1 denotes a white LED, and three LEDs are driven in series in this case, but may be driven in parallel. The number driven in series is not particularly limited to three. A terminal A is an output of the LED drive step-up circuit 4 such as a DC / DC converter, and is connected to the anode of the white LED 1. The LED drive step-up circuit 4 is indispensable in order to prevent that the white LED 1 cannot be turned on when the voltage of the battery 3 drops because the forward voltage VF of the white LED 1 is large. Even in the case of LEDs having a small VF, boosting is necessary in case of series connection. 2 is a constant current source, which is connected to the cathode of LED1. This current value is variable, and this current value is
By adjusting with 1, the brightness of the LED 1 can be adjusted. When the LED drive is performed without the constant current drive, when the output voltage of the LED drive step-up circuit 4 changes due to a load change or the like, the brightness fluctuates in conjunction therewith, thereby causing display flicker. In order to reduce the number of current source circuits, LE
A method of driving by connecting D in series is often used. This allows equal current to flow through all LEDs,
If the LED elements of the same lot are used, the relative luminance variation between the elements is not large, so that the current value can be adjusted for each lot to reduce the absolute luminance variation. However, in the configuration of the conventional white LED driving circuit shown in FIG.
The output voltage of the D drive step-up circuit 4 is the same as that of all the L connected in series.
It must be set to be equal to or greater than the sum of the maximum values of the VF standard in the ED. Since there is a difference between the margin of the VF standard and the actual VF value, a power loss occurs due to the drive current and the efficiency is reduced. The present invention realizes a constant current driving method by controlling the output voltage of a booster circuit, and realizes LE with a minimum power loss.
D is driven. In order to achieve this object, the present invention is characterized in that the output voltage of an LED drive booster circuit is controlled so that a constant current set to an LED flows. It is. [0010] With this configuration, power loss in the entire drive system can be minimized. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The basic concept of the present invention will be described with reference to the drawings. FIG. 1 is different from the conventional configuration shown in FIG. 3 in that the constant current source 2 is replaced by a current detection circuit 9 and the output voltage value of the LED drive step-up circuit 4 is changed so that the current value flowing through the LED 1 becomes constant. 3 shows a configuration for controlling. [0013] The voltage control method also depends on a system such as a DC / DC circuit. For example, it is conceivable to change the input voltage of the VCO and change the pulse width of the PWM method. FIG. 2 shows a more specific embodiment. In FIG. 2, a DC / DC converter 10 is used as the LED drive step-up circuit 4. Detection resistor 5
, The current ILED flowing through the LED 1 is detected by the comparator 7 and compared with the value set in the reference voltage source 6 by the comparator 7. When the voltage of the detection resistor 5 is lower than the reference voltage source 6,
The output of the LED drive step-up circuit 4 is raised by changing the input voltage of the VCO or the like of the output voltage control circuit 8, and when the input voltage is higher than the set voltage, the output is lowered. As a result, a voltage is output which is the sum of the sum of the VFs of the LEDs at the drive voltage and the voltage generated at the current detection resistor. The efficiency of this circuit is only the efficiency of the LED drive booster circuit 4 and the loss due to the current detection circuit. Is determined. As a specific example, in the case of a typical white LED, the standard value of VF is about 3.6V. But VF
Since the standard value is about 4V, if the output of the booster circuit is set to a constant voltage, if three LEDs are to be driven, an output voltage of at least the required voltage of the constant current drive circuit plus three lights x 4V is required. become. Therefore, in the case of a 20 mA load, (4V-3.6 V) × 3 lamps × 20 mA is a loss. This corresponds to about 10% of the power required for driving the LED. As described above, according to the present invention, when the LED is driven at a constant current, by controlling the output voltage of the booster circuit, high efficiency driving can be realized regardless of the VF standard of the LED.
Since the output of the booster circuit is controlled to the required minimum drive voltage according to the F value, no loss due to the VF margin occurs.
[Brief description of the drawings] FIG. 1 is a conceptual diagram illustrating the present invention. FIG. 2 illustrates one embodiment of the present invention. FIG. 3 is a conceptual diagram of the related art. [Explanation of symbols] 1 LED 2 Constant current drive circuit 3 batteries 4 LED drive booster circuit 5 Current detection resistor 6 Current setting reference voltage source 7 Comparator 8 Output voltage control circuit 9 Current detection circuit 10 DC / DC converter

Claims (1)

  1. Claims: 1. An LED drive circuit that controls a booster circuit output voltage so that a constant current set to an LED flows, thereby minimizing power loss in the entire drive system.
JP2001351464A 2001-11-16 2001-11-16 High-efficiency led driving system Pending JP2003152224A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2001351464A JP2003152224A (en) 2001-11-16 2001-11-16 High-efficiency led driving system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2001351464A JP2003152224A (en) 2001-11-16 2001-11-16 High-efficiency led driving system

Publications (1)

Publication Number Publication Date
JP2003152224A true JP2003152224A (en) 2003-05-23

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
JP2001351464A Pending JP2003152224A (en) 2001-11-16 2001-11-16 High-efficiency led driving system

Country Status (1)

Country Link
JP (1) JP2003152224A (en)

Cited By (26)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003103061A1 (en) * 2002-05-31 2003-12-11 Sony Corporation Light emitting element drive device and mobile device using the same
JP2005136157A (en) * 2003-10-30 2005-05-26 Rohm Co Ltd Light emitting element driving device, display module having same driving device, and electronic device having same module
WO2005104246A1 (en) * 2004-04-20 2005-11-03 Sony Corporation Constant current driver, back light source and color liquid crystal display
JP2006270402A (en) * 2005-03-23 2006-10-05 Sanyo Electric Co Ltd Pwm driver circuit
WO2006137303A1 (en) * 2005-06-20 2006-12-28 Matsushita Electric Industrial Co., Ltd. Semiconductor laser driving circuit, and optical disc device and integrated circuit provided with semiconductor laser driving circuit
JP2007035938A (en) * 2005-07-27 2007-02-08 Noritsu Koki Co Ltd Led driving device, and method for controlling the same
JP2007086778A (en) * 2005-09-16 2007-04-05 Samsung Electronics Co Ltd Display device
JP2007335345A (en) * 2006-06-19 2007-12-27 Auto Network Gijutsu Kenkyusho:Kk Mounting structure of automobile led lamp
JP2008008714A (en) * 2006-06-28 2008-01-17 Ricoh Co Ltd Semiconductor measuring apparatus
JP2008311248A (en) * 2007-06-12 2008-12-25 Mitsubishi Electric Corp Power supply device, light emitting diode lighting device, and guide light device
JP2009016280A (en) * 2007-07-06 2009-01-22 Nec Lcd Technologies Ltd Light emission control circuit, light emission control method, surface lighting apparatus, and liquid crystal display device with the surface lighting apparatus
EP2079156A2 (en) 2008-01-08 2009-07-15 Mitsumi Electric Co., Ltd. Direct-current power supply device, power supply device for driving LED and semiconductor integrated circuit for controlling power supply
WO2009094379A1 (en) * 2008-01-25 2009-07-30 Eveready Battery Company, Inc. Lighting device having boost circuitry
JP2009231147A (en) * 2008-03-24 2009-10-08 Toshiba Lighting & Technology Corp Power supply device and luminaire
US7642734B2 (en) 2005-02-02 2010-01-05 Osram Gesellschaft Mit Beschraenkter Haftung Method and system for dimming light sources
JP2010016198A (en) * 2008-07-03 2010-01-21 Panasonic Corp Semiconductor light source driving device and semiconductor light source driving method
JP2011502319A (en) * 2007-11-20 2011-01-20 シンボル テクノロジーズ インコーポレイテッド Image barcode reader with illumination control system
JP2011029615A (en) * 2009-07-02 2011-02-10 Fujitsu Semiconductor Ltd Led driving circuit, and semiconductor device
CN101533607B (en) * 2008-03-14 2011-03-30 原景科技股份有限公司 Driving circuit for light emitting diodes and method for driving the light emitting diodes
CN101436386B (en) * 2007-11-15 2011-06-08 中华映管股份有限公司 Drive device for backlight module unit
US8314757B2 (en) 2007-12-10 2012-11-20 Sanken Electric Co., Ltd. Apparatus for driving light emitting elements and electronic appliance employing the apparatus
WO2012155327A1 (en) * 2011-05-16 2012-11-22 深圳世强电讯有限公司 Led constant current drive circuit
US8421424B2 (en) 2009-10-01 2013-04-16 Panasonic Corporation Current driver circuit
US8552963B2 (en) 2004-11-30 2013-10-08 Rohm Co., Ltd. Switching regulator control circuit, current drive circuit, light emitting apparatus, and information terminal apparatus
CN106658840A (en) * 2016-12-09 2017-05-10 上海航空电器有限公司 Methods and device used for controlling luminance of airplane LED indication lamp
CN106793252A (en) * 2016-11-25 2017-05-31 上海航空电器有限公司 A kind of LED illumination light-dimming method of voltage and dutycycle dual control

Cited By (42)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8618745B2 (en) 2002-05-31 2013-12-31 Sony Corporation Light emitting element drive apparatus and portable apparatus using same
US9041643B2 (en) 2002-05-31 2015-05-26 Sony Corporation Light emitting element drive apparatus and portable apparatus using same
US8941581B2 (en) 2002-05-31 2015-01-27 Sony Corporation Light emitting element drive apparatus and portable apparatus using same
US9717124B2 (en) 2002-05-31 2017-07-25 Sony Corporation Light emitting element drive apparatus and portable apparatus using same
US8654059B2 (en) 2002-05-31 2014-02-18 Sony Corporation Light emitting element drive apparatus and portable apparatus using same
WO2003103061A1 (en) * 2002-05-31 2003-12-11 Sony Corporation Light emitting element drive device and mobile device using the same
US9148927B2 (en) 2002-05-31 2015-09-29 Sony Corporation Light emitting element drive apparatus and portable apparatus using same
US7365718B2 (en) 2002-05-31 2008-04-29 Sony Corporation Light emitting element drive apparatus and portable apparatus using the same
JP2005136157A (en) * 2003-10-30 2005-05-26 Rohm Co Ltd Light emitting element driving device, display module having same driving device, and electronic device having same module
WO2005104246A1 (en) * 2004-04-20 2005-11-03 Sony Corporation Constant current driver, back light source and color liquid crystal display
US7538497B2 (en) 2004-04-20 2009-05-26 Sony Corporation Constant current driver, back light source and color liquid crystal display
US8552963B2 (en) 2004-11-30 2013-10-08 Rohm Co., Ltd. Switching regulator control circuit, current drive circuit, light emitting apparatus, and information terminal apparatus
US7642734B2 (en) 2005-02-02 2010-01-05 Osram Gesellschaft Mit Beschraenkter Haftung Method and system for dimming light sources
JP2006270402A (en) * 2005-03-23 2006-10-05 Sanyo Electric Co Ltd Pwm driver circuit
JPWO2006137303A1 (en) * 2005-06-20 2009-01-15 パナソニック株式会社 Semiconductor laser driving circuit, and optical disk device and integrated circuit provided with semiconductor laser driving circuit
WO2006137303A1 (en) * 2005-06-20 2006-12-28 Matsushita Electric Industrial Co., Ltd. Semiconductor laser driving circuit, and optical disc device and integrated circuit provided with semiconductor laser driving circuit
US8036254B2 (en) 2005-06-20 2011-10-11 Panasonic Corporation Semiconductor laser driving circuit, and optical disc device and integrated circuit provided with semiconductor laser driving circuit
JP2007035938A (en) * 2005-07-27 2007-02-08 Noritsu Koki Co Ltd Led driving device, and method for controlling the same
JP2007086778A (en) * 2005-09-16 2007-04-05 Samsung Electronics Co Ltd Display device
JP4663606B2 (en) * 2005-09-16 2011-04-06 三星電子株式会社Samsung Electronics Co.,Ltd. Display device
JP2007335345A (en) * 2006-06-19 2007-12-27 Auto Network Gijutsu Kenkyusho:Kk Mounting structure of automobile led lamp
JP4746489B2 (en) * 2006-06-28 2011-08-10 株式会社リコー Semiconductor measuring equipment
JP2008008714A (en) * 2006-06-28 2008-01-17 Ricoh Co Ltd Semiconductor measuring apparatus
JP2008311248A (en) * 2007-06-12 2008-12-25 Mitsubishi Electric Corp Power supply device, light emitting diode lighting device, and guide light device
JP2009016280A (en) * 2007-07-06 2009-01-22 Nec Lcd Technologies Ltd Light emission control circuit, light emission control method, surface lighting apparatus, and liquid crystal display device with the surface lighting apparatus
US8896516B2 (en) 2007-07-06 2014-11-25 Nlt Technologies, Ltd. Light emission control circuit, light emission control method, flat illuminating device, and liquid crystal display device having the same device
CN101436386B (en) * 2007-11-15 2011-06-08 中华映管股份有限公司 Drive device for backlight module unit
JP2011502319A (en) * 2007-11-20 2011-01-20 シンボル テクノロジーズ インコーポレイテッド Image barcode reader with illumination control system
US8314757B2 (en) 2007-12-10 2012-11-20 Sanken Electric Co., Ltd. Apparatus for driving light emitting elements and electronic appliance employing the apparatus
US7977890B2 (en) 2008-01-08 2011-07-12 Mitsumi Electric Co., Ltd. Direct current power supply device, power supply device for driving LED and semiconductor integrated circuit for controlling power supply
EP2079156A2 (en) 2008-01-08 2009-07-15 Mitsumi Electric Co., Ltd. Direct-current power supply device, power supply device for driving LED and semiconductor integrated circuit for controlling power supply
WO2009094379A1 (en) * 2008-01-25 2009-07-30 Eveready Battery Company, Inc. Lighting device having boost circuitry
US9101022B2 (en) 2008-01-25 2015-08-04 Eveready Battery Company, Inc. Lighting device having boost circuitry
CN101533607B (en) * 2008-03-14 2011-03-30 原景科技股份有限公司 Driving circuit for light emitting diodes and method for driving the light emitting diodes
JP2009231147A (en) * 2008-03-24 2009-10-08 Toshiba Lighting & Technology Corp Power supply device and luminaire
JP2010016198A (en) * 2008-07-03 2010-01-21 Panasonic Corp Semiconductor light source driving device and semiconductor light source driving method
JP2011029615A (en) * 2009-07-02 2011-02-10 Fujitsu Semiconductor Ltd Led driving circuit, and semiconductor device
US8829864B2 (en) 2009-10-01 2014-09-09 Collabo Innovations, Inc. Current driver circuit
US8421424B2 (en) 2009-10-01 2013-04-16 Panasonic Corporation Current driver circuit
WO2012155327A1 (en) * 2011-05-16 2012-11-22 深圳世强电讯有限公司 Led constant current drive circuit
CN106793252A (en) * 2016-11-25 2017-05-31 上海航空电器有限公司 A kind of LED illumination light-dimming method of voltage and dutycycle dual control
CN106658840A (en) * 2016-12-09 2017-05-10 上海航空电器有限公司 Methods and device used for controlling luminance of airplane LED indication lamp

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