Browse Prior Art Database

Density Gauge

IP.com Disclosure Number: IPCOM000078322D
Original Publication Date: 1972-Dec-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Pennell, GH: AUTHOR [+2]

Abstract

Document dispensing equipment must be provided with a safety device so that a malfunction in the dispensing equipment will not cause multiple-document feed. A safety device suitable for preventing double-document dispensing uses a preset photosensitive element, which measures the opacity of the document and permits dispensing when the light transmitted through the document is above a preset threshold. Transmitted light below the threshold indicates a multiple document and activates bypass equipment, which prevents the dispenser from dispensing the double document.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 80% of the total text.

Page 1 of 1

Density Gauge

Document dispensing equipment must be provided with a safety device so that a malfunction in the dispensing equipment will not cause multiple-document feed. A safety device suitable for preventing double-document dispensing uses a preset photosensitive element, which measures the opacity of the document and permits dispensing when the light transmitted through the document is above a preset threshold. Transmitted light below the threshold indicates a multiple document and activates bypass equipment, which prevents the dispenser from dispensing the double document.

The photosensitive element can be calibrated or recalibrated using documents in average condition. However, where the documents are valuable such as is the case with currency, their use involves a security problem.

Colored and white paper stock were tried as an alternative for calibrating the threshold of the photosensor. However, the spectral response of the sensors available was such that they were not linear over a broad range, thus, very minor variations of color resulted in significant changes in relative opacity. In addition, the spectral output of the available light sources introduced additional nonlinearities which further compounded the problem. Plain white paper of sufficient opacity was not practical due to the increased thickness of the stock required.

White paper stock of the correct thickness with black parallel lines of fixed width with variable-width white, spaced to achie...