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Browse Prior Art Database

Universally Orientable Anti-Theft Warning Device

IP.com Disclosure Number: IPCOM000043737D
Original Publication Date: 1984-Sep-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 3 page(s) / 41K

Publishing Venue

IBM

Related People

Coffman, DH: AUTHOR [+2]

Abstract

Portable instruments, such as personal computers and their display monitors, are vulnerable to theft or unauthorized tampering, particularly in school environments. An alternative to locking the instrument to a secure foundation (which might not be available in many circumstances) is to provide, as an integral attachment, an alarm device sensitive to motion. A device of this character is described in [*]. That device attaches to the instrument which it is supposed to protect, and when electrically "armed", senses movement of that instrument. When the instrument is moved, the device issues an audible alarm. This earlier device had a sensitivity to movement of the host instrument which was not uniform, but rather could be influenced by the orientation of the instrument and the direction and rate of movement.

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Universally Orientable Anti-Theft Warning Device

Portable instruments, such as personal computers and their display monitors, are vulnerable to theft or unauthorized tampering, particularly in school environments. An alternative to locking the instrument to a secure foundation (which might not be available in many circumstances) is to provide, as an integral attachment, an alarm device sensitive to motion. A device of this character is described in [*]. That device attaches to the instrument which it is supposed to protect, and when electrically "armed", senses movement of that instrument. When the instrument is moved, the device issues an audible alarm. This earlier device had a sensitivity to movement of the host instrument which was not uniform, but rather could be influenced by the orientation of the instrument and the direction and rate of movement. The device described below provides more uniform and more controllable sensitivity. The motion-sensing element of the present device (Figs. 1 and 2) consists of a cube 1 of plastic or ceramic, built in two halves 1a, 1b. The insides of these halves form a closed hollow sphere (Fig. 2). Each half contains a multilayered printed circuit whose conductive layers terminate at various positions on the interior spherical surface. As suggested in Fig. 3, the common layer 2 nearest to the surface of the sphere contains openings 3 surrounding "islands" of insulation 4. These "islands" surround and electrically isolate contact point terminations 6, 7, 8,..., of the other (buried) conductive layers.

These point terminations are preferably clustered in hexagonal 18 point arrays, as shown in Fig. 4, with neighboring points connected to different inner layers. A drop of mercury 9 (Fig. 5), placed in the sphere before the halves are sealed, forms a movable bridging contact relative to...