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Light emitting element drive device and electronic apparatus having light emitting element

A technology of light-emitting components and driving devices, which can be applied to electroluminescence light sources, instruments, electrical components, etc., and can solve problems such as power efficiency reduction

Inactive Publication Date: 2007-11-28
ROHM CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, it is necessary to make the constant current drivers 33 to 35 large-scale devices, and the power efficiency is lowered.

Method used

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  • Light emitting element drive device and electronic apparatus having light emitting element
  • Light emitting element drive device and electronic apparatus having light emitting element
  • Light emitting element drive device and electronic apparatus having light emitting element

Examples

Experimental program
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Embodiment Construction

[0026] Hereinafter, an embodiment of an electronic device according to the present invention using an LED as a light emitting element will be described with reference to the drawings.

[0027] FIG. 1 is an overall configuration diagram of an electronic device including a light emitting element according to an embodiment of the present invention. In addition, FIG. 2 is a diagram of a specific example of a selection circuit that selects and outputs the lowest voltage among a plurality of input voltages. In addition, FIG. 3 is a graph showing current-voltage characteristics of LEDs as light-emitting elements.

[0028] In FIG. 1 , the electronic device is configured to include a driving device (hereinafter referred to as a driving device) 10 and a display device (hereinafter referred to as a display device) 20 .

[0029] The display device 20 is a device used in a display portion of an electronic device such as a mobile phone, and is configured as an IC chip (chip).

[0030] In ...

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PUM

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Abstract

An electronic apparatus is equipped with light emitting elements (21-26) such as LEDs. The light emitting elements are driven by a power supply circuit of the drive device (10) at a high step-up voltage (Vh). The drive device (10) has a multiplicity of constant-current drivers (12-14), a selection circuit (18), and a control circuit (11). The drivers are turned ON or OFF in accordance with respective instruction signals (S1-S3) supplied thereto to provide associated series with currents to activate the series for emission of light when associated drivers are turned ON. The selection circuit (18) selects the lowest one of the voltages impressed on the drivers and outputs the selected lowest voltage as a detection voltage. The control circuit (11) automatically controls the voltage Vh so as to equilibrate the detection voltage with a low reference voltage at which the drivers can perform required constant-current operations. Thus, the drive device can fully activate the light emitting elements for emission of light while suppressing energy loss in the drivers.

Description

technical field [0001] The present invention relates to a light-emitting element drive device for driving a light-emitting element driven by a high voltage such as an LED (light-emitting diode), and an electronic device including a light-emitting element. Background technique [0002] Light-emitting elements such as LEDs are used not only as display elements themselves, but also as light sources for backlights of LCDs (liquid crystal displays). The number used depends on the type of display and the amount of light required. [0003] 4 is a diagram showing a conventional structure for driving LEDs of electronic devices such as mobile phones using LEDs as light emitting elements, and is composed of a driving device 30 and a display device 40 . [0004] The display device 40, for the display part, includes: a first light-emitting element series in which two LED41 and LED42 are arranged in series, a second light-emitting element series in which two LED43 and LED44 are arranged ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01L33/00G09G3/30G09G3/20H05B37/02G09G3/14H05B44/00
CPCH05B33/0815H05B33/0851H05B33/0827G09G3/30H05B45/10H05B45/46H05B45/38G09G3/32
Inventor 堀内幸人星野健山本勋
Owner ROHM CO LTD