Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Secure Document Feature for Copy Machines

IP.com Disclosure Number: IPCOM000079240D
Original Publication Date: 1973-Feb-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Cecil, TF: AUTHOR [+2]

Abstract

Fig. 1 shows a document plane 10 of an electrophotographic copying apparatus which has had etched therein, an inductance coil 12 for security control of the copier. A high-Q tuned circuit 14 is connected to the inductance coil and tuned to the operating level of the coil. The output of the tuned circuit is fed to a voltage change detection circuit 16 which, in turn, senses any voltage output change due to a change in the inductance of coil 12. The voltage change detection circuit 16 provides a control output signal to the copier disable control 18, which functions to disable the copier upon the sensing of a change of voltage from the high-Q tuned circuit 14.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 60% of the total text.

Page 1 of 2

Secure Document Feature for Copy Machines

Fig. 1 shows a document plane 10 of an electrophotographic copying apparatus which has had etched therein, an inductance coil 12 for security control of the copier. A high-Q tuned circuit 14 is connected to the inductance coil and tuned to the operating level of the coil. The output of the tuned circuit is fed to a voltage change detection circuit 16 which, in turn, senses any voltage output change due to a change in the inductance of coil 12. The voltage change detection circuit 16 provides a control output signal to the copier disable control 18, which functions to disable the copier upon the sensing of a change of voltage from the high-Q tuned circuit 14.

Fig. 2 illustrates a document 20 which has been designated as a noncopyable document for security reasons. This document comprises a paper sheet 22 with the normal legends and indicia printed, typed, or otherwise made legible thereon and a metal foil 24 laminated onto the paper sheet 22.

When the document 20 is placed on document plane 10 for copying, the metal foil 24 serves as a shorted turn in a transformer in which the primary is the inductance coil 12. The reflected load of the shorted turn changes the residence frequency of the tuned circuit 14. The voltage change as a result in the shift of the tuned circuit 14, causes the voltage change detection circuit 16 to produce a control signal which operates the copier disable control 18. This can be a general power sh...