Unlock instant, AI-driven research and patent intelligence for your innovation.

Power supply device, light emitting device using such power supply device, and electronic device

A technology for power supply devices and voltage generating circuits, which can be applied to conversion equipment without intermediate conversion to AC, electric light sources, lighting devices, etc., and can solve problems such as deterioration of circuit efficiency

Inactive Publication Date: 2007-11-07
ROHM CO LTD
View PDF2 Cites 38 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0011] The efficiency of the charge pump circuit deteriorates as the boost rate increases, so as described above, if a margin is set for the threshold voltage for stably operating the constant current circuit, the efficiency of the entire circuit deteriorates.

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • Power supply device, light emitting device using such power supply device, and electronic device
  • Power supply device, light emitting device using such power supply device, and electronic device
  • Power supply device, light emitting device using such power supply device, and electronic device

Examples

Experimental program
Comparison scheme
Effect test

Embodiment Construction

[0047] Fig. 1 shows a light-emitting device 1000 according to an embodiment of the present invention. In the following figures, the same reference numerals are given to the same constituent elements, and repeated descriptions are appropriately omitted.

[0048] The light emitting device 1000 is mounted on an electronic device such as a mobile phone terminal or a PDA, and has a function as a backlight of a liquid crystal. In FIG. 1, a liquid crystal panel 510 is shown together with the light emitting device 1000. The light emitting diode 300 is provided on the back of the liquid crystal panel 510 and has a function as a backlight.

[0049] The light-emitting device 1000 includes: a light-emitting diode 300 as a light-emitting element; and a power supply device 100 for driving the light-emitting diode 300. The light emitting device 1000 is mounted on an information terminal driven by a battery 500, and the power supply device 100 boosts the battery voltage Vbat output from the batte...

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

PUM

No PUM Login to View More

Abstract

A power supply device which can perform higher efficiency operation is provided by correctly setting a driving voltage of a load circuit. In the power supply device (100) for driving a light emitting diode (300), which is the load circuit, with a constant current, a constant current circuit (22) is provided on a drive path of the load circuit. A charge pump circuit (10), which is a voltage generating circuit, outputs a driving voltage to the light emitting diode (300). A monitoring circuit (30) monitors voltages at both ends of the constant current circuit (22). The monitoring circuit (30) includes a voltage source for generating a threshold voltage which follows voltage fluctuation with which the constant current circuit (22) can stably operate, compares the voltages at the both ends of the constant current circuit with the threshold voltage generated by the voltage source, and outputs the comparison results (Vs) to a control section (24). The control section (24) controls the charge pump circuit (10) based on the output from the monitoring circuit (30).

Description

Technical field [0001] The present invention relates to a power supply device. Background technique [0002] In recent years, in small information terminals such as mobile phones and PDAs (Personal Digital Assistance), there are, for example, light-emitting diodes used in the backlight of liquid crystals (hereinafter also referred to as LEDs), which require a voltage higher than the output voltage of the battery. device of. In these small information terminals, lithium-ion batteries are often used, and their output voltage is usually about 3.5V, which is about 4.2V when fully charged, but LEDs require a higher voltage than the battery voltage as their driving voltage. In this way, when a voltage higher than the battery voltage is required, a boost-type power supply device such as a charge pump circuit is used to boost the battery voltage to obtain the voltage required to drive a load circuit such as an LED. [0003] According to such a power supply device, when driving the LED, b...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

Application Information

Patent Timeline
no application Login to View More
IPC IPC(8): H02M3/07H01L33/00H05B37/02
Inventor 山本勋伊藤智将
Owner ROHM CO LTD