Browse Prior Art Database

A Method of Providing an Ambient Light sensor for Hand Held Terminals

IP.com Disclosure Number: IPCOM000131180D
Original Publication Date: 2005-Nov-09
Included in the Prior Art Database: 2005-Nov-09
Document File: 2 page(s) / 27K

Publishing Venue

Motorola

Related People

Yona Newman: AUTHOR

Abstract

Using an imager based bar code scanner as an ambient light sensor to adjust the screen illumination.

This text was extracted from a Microsoft Word document.
This is the abbreviated version, containing approximately 56% of the total text.

A Method of Providing an Ambient Light sensor for Hand Held Terminals 

                    By Yona Newman (Motorola Distinguished Innovator)

1. Abstract

                    Using an imager based bar code scanner as an ambient light sensor to adjust the screen illumination.

2. Introduction and current art

                    In many hand held terminals or Portable Data Appliances (PDA’s) a light sensor is fitted that automatically adjusts the screen illumination to suit the ambient lighting.

                   

                   

3. Disadvantages of current art

On ruggedized handheld terminal products that do not have this feature it adds cost to the product at the design and manufacturing stages to add this, and it is almost impossible to offer this as a field retro-fit.

4. Description of the invention

                    4.1 Introduction.

                    The proposed method of sensing ambient illumination relies on the data terminal being fitted with an imager based barcode scanner. This is common today, as our customers need to capture both simple 1-D (one dimensional) barcodes and complex 2-D (two dimensional) barcodes. In addition, there is a frequent requirement to capture images of, for example, signatures, postal items, and so on.

                    All these considerations lead to the use of an imager in these terminals.

                    4.2 Description of the method.

                    The imager is switched on periodically, we suggest once every 10 seconds, and an image captured. The image pixel readings are averaged to give the average background illumination in the region within the imager field of view.

                    Further, successive readings are averaged to develop a long-time trend figure for the average ambient illumination. If this average changes by more than 20% over more than 5 minutes then the screen illumination is automatically increased or decreased to suit.

                    The 20% change comes fro...