Mailing machine having optical sensors with improved immunity to ambient

US8464855B2 · kind B2 · utility

Assignee

• Pitney Bowes Inc. · US

Inventors

• Michael J. Lorello · Guilford, US
• Gary S. Jacobson · Norwalk, US
• George J. Doutney · Sandy Hook, US

Key dates

• Filing date: Mar 21, 2011
• Grant date: Jun 18, 2013
• Expiry date: Nov 2, 2031

Classification

• Technology area (CPC G): Physics
• CPC primary: G01J1/4204
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

Circuitry to control reflective optical sensors is provided that reduces false detections due to ambient light without compromising the performance of the optical sensors to detect dark materials. A reflective optical sensor includes an emitter LED and photo-detector arranged to receive light from the LED that is reflected by an object being detected. A first input of a comparator is coupled to the output of the photo-detector. A second input of the comparator is coupled to the output of the photo-detector through a filtering circuit. The filtering circuit operates to filter the detector's output and adaptively adjust the trigger threshold of the comparator, thereby enabling the photo-detector to be sensitive enough to detect dark mail pieces, i.e., those mail pieces that are minimally reflective, while being immune to repeated false triggers due to excessive ambient light.