Browse Prior Art Database

Anti-Theft Device for Portable Instruments

IP.com Disclosure Number: IPCOM000042342D
Original Publication Date: 1984-May-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Coffman, DH: AUTHOR [+2]

Abstract

Portable instruments, such as personal computers, are obviously vulnerable to theft or tampering, particularly in school environments. The device described here is designed to prevent such activities. Referring to the block diagram in Fig. 1, the device, indicated at 1, comprises tape 2, for attaching it to the inside of the enclosure (not shown) of the instrument to be protected, an arming switch 3, an audible alarm 4, a tilt or movement detector 5, and a battery or other internal power source 6. Details of the detector and its operation are shown in Figs. 2-4. The detector consists of a hollow plastic cube having slightly concaved interior walls 8 (Fig. 3) on each of its six sides. Each wall contains a printed circuit pattern 9 of discrete, electrically separated lands.

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Anti-Theft Device for Portable Instruments

Portable instruments, such as personal computers, are obviously vulnerable to theft or tampering, particularly in school environments. The device described here is designed to prevent such activities. Referring to the block diagram in Fig. 1, the device, indicated at 1, comprises tape 2, for attaching it to the inside of the enclosure (not shown) of the instrument to be protected, an arming switch 3, an audible alarm 4, a tilt or movement detector 5, and a battery or other internal power source 6. Details of the detector and its operation are shown in Figs. 2-4. The detector consists of a hollow plastic cube having slightly concaved interior walls 8 (Fig. 3) on each of its six sides. Each wall contains a printed circuit pattern 9 of discrete, electrically separated lands. Alternate lands are connected to different ones of the two output leads 10 which in turn extend to the alarm circuit. Before installation of the last side of the cube, a small quantity of breaker oil and a drop or ball of mercury 11 are inserted into the cube interior. This material serves to detect displacement of the cube by shorting out otherwise isolated pairs of lands. At installation, the device is mounted with its axes parallel to those of the instrument to be protected (Fig. 4) and with its switch 3 in the off position. The arming switch may be operated -- either manually, or automatically when power is removed from the protected instrument -- t...