Burglar alarm system for an electronic apparatus with a slot

• US 6,014,079 A
• Filed: 10/20/1998
• Issued: 01/11/2000
• Est. Priority Date: 10/20/1998
• Status: Expired due to Fees

• Current Assignee: Huang, Dennis
• Original Assignee: Huang, Dennis
• Inventors: Huang, Dennis
• Primary Examiner(s): Hofsass, Jeffery A.
• Assistant Examiner(s): TRIEU, VAN THANH
• Application Number:
  US09/175,334
• Time in Patent Office: 448 Days
• Field of Search: 340/539, 340/568.1, 340/568.2, 340/571, 340/572.1, 340/572.8
• US Class Current: 340/571
• CPC Class Codes: G08B 13/1427 with transmitter-receiver for distance detection
• CPC Class Codes: G08B 21/0252 System arrangements wherein the child unit emits, i.e. the child unit incorporates the emitter

Abstract

A burglar alarm system for an electronic apparatus with a slot comprises a radio transmitter unit and a radio receiver unit. The radio transmitter unit can transmit a radio code signal when inserted into the slot of the electronic apparatus. The radio receiver unit can be carried by a user to receive the code signal from the radio transmitter unit. The radio receiver unit automatically output an alarm signal when moved away from the electronic apparatus beyond a predetermined distance due to loss of reception of the code signal from the radio transmitter unit.

Claims

1. A burglar alarm system for an electronic apparatus with a slot arranged to receive a removable interface device or information storage medium, comprising:

a radio transmitter unit for insertion into the slot of said electronic apparatus, said radio transmitter unit comprising a casing fitting the slot of said electronic apparatus, a transmitting circuit mounted in said casing, and an on/off switch, said transmitting circuit comprised of an encoder, a radio signal transmitter, a transmitting antenna, and a transmitting control device, said encoder being controlled by said transmitting control device to output a code signal to said radio signal transmitted when said on/off switch is switched on, enabling the code signal to be transmitted into the air by radio by said radio signal transmitter through said transmitting antenna, wherein said on/off switch of said radio transmitter unit is arranged to be switched off when said radio transmitter unit is removed from the slot of said electronic apparatus and switched on when said radio transmitter unit is inserted in the slot of the electronic apparatus; and

a radio receiver unit, said radio receiver unit comprising a receiving antenna which receives the code signal from said radio transmitter unit, a decoder which recognizes the code signal received by said receiving antenna, an alarm device, a receiving control unit which drives said alarm device to output an alarm signal when said receiving antenna receives no signal from said radio transmitter unit, and switch means to turn on/off said radio receiver unit.

2. The burglar alarm system of claim 1 wherein said radio transmitter unit further comprises a transmitting time sequence circuit which controls the transmitting frequency of said code signal per every unit time.

3. The burglar alarm system of claim 1 wherein said switch means of said radio receiver unit further provides a search mode at which said receiving control device drives said alarm device to output an alarm signal when said radio receiver unit receives the code signal from said radio transmitter unit.