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Browse Prior Art Database

INTEGRATED LED/PHOTODETECTOR

IP.com Disclosure Number: IPCOM000006664D
Original Publication Date: 1992-Dec-01
Included in the Prior Art Database: 2002-Jan-21
Document File: 1 page(s) / 50K

Publishing Venue

Motorola

Related People

Allison A. Mather: AUTHOR [+3]

Abstract

The trend in the electronic industry is towards min- iaturization. As products become smaller, the available printed circuit board space is also reduced. This creates the need to integrate multiple components in single pack- ages to save space. Two components in particular for which joint packaging would be advantageous are the LED and phototransistor.

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MOIOROLA INC. Technical Developments Volume 17 December 1992

INTEGRATED LED/PHOTODETECTOR

By Allison A. blather, Paul E. Gorday, and Rodney S. Whaley

  The trend in the electronic industry is towards min- iaturization. As products become smaller, the available printed circuit board space is also reduced. This creates the need to integrate multiple components in single pack- ages to save space. Two components in particular for which joint packaging would be advantageous are the LED and phototransistor.

  The LED is used as an alerting mechanism to signal a received message or to indicate power-up. The phototransistor is used to detect the available light level. With the information from the phototransistor, the

microprocessor can turn on various lighting mechanisms (lamps, EL backlighting, etc.) which allow the user to view the display under low light conditions. Both cir- cuits require a viewing port with a lense located on the housing of the pager. By combining the LED and the phototransistor, a significant space savings can be real- ized. In addition, only a single lense in the housing will be required, thus lowering tooling costs. The integrated LED/phototransistor is shown below. (Note, a partition is used between the devices to prevent the LED from causing false light level readings in the phototransistor.)

Side View

Phototransistor _

Top View

Figure. Top and Side Views of Integrated LED/Phototransistor

0 Motorola. 1°C. ,992

47

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