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MINIMUM POWER CONSUMPTION DRIVE FOR TWO LIGHT EMITTING DEVICES

IP.com Disclosure Number: IPCOM000006017D
Original Publication Date: 1990-Oct-01
Included in the Prior Art Database: 2001-Nov-26
Document File: 1 page(s) / 58K

Publishing Venue

Motorola

Related People

Tuan K. Nguyen: AUTHOR [+3]

Abstract

This idea is a means for reducing the power consumption required to drive two light emitting devices for visual alert (allowing for color mixing) and/or dual source illumination of a panel. A unique electrical circuit utilizes two high frequency signal sources to sequentially strobe two light emitting devices at a rate higher than tha retina capture rate. The frequency sources are, in the preferred embodiment, already available from the apparatus the system is in (example a pager).

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MOlYlROLA Technical Developments Volume 11 October 1990

MINIMUM POWER CONSUMPTION DRIVE FOR TWO LIGHT EMITTING DEVICES

                 by Tuan K. Nguyen, Tom Rollins, and David Hayes This idea is a means for reducing the power consumption required to drive two light emitting devices for visual alert (allowing for color mixing) and/or dual source illumination of a panel. A unique electrical circuit utilizes two high frequency signal sources to sequentially strobe two light emitting devices at a rate higher than tha retina capture rate. The frequency sources are, in the preferred embodiment, already available from the apparatus the system is in (example a pager).

DESCRIPTION OF THE DEVICE OPERATION: This idea utilizes the fact that the human eye will always perceive a light source, that strobes at a frequency higher than 25 Hertz, as a continuously ON source.

The pager has two on board high frequency (> 25 Hz) sources:
a) a high frequency oscillator driving the DC-DC converter circuit (80 KHz for example)
b) an audio alert frequency generator (3.2KHz for example) The pager mentioned above has two light emitting sources (2 color LED's for example) to achieve multiple color visual alerts. The two LED can be in one single package or in two separate packages. Let LED1 be red and LED2 be green for example.

The driving ports are capable of sinking the current from the LED's:
a) the Alert Port1 is Hi-2 in the OFF state
b) the Control Port2 is either High, Low, or Hi-2

Note: In the ap...