Alarm system for preventing loss of personal property

• US 5,781,109 A
• Filed: 09/05/1996
• Issued: 07/14/1998
• Est. Priority Date: 09/05/1996
• Status: Expired due to Fees

• Current Assignee: Shozo Nakajima
• Original Assignee: Shozo Nakajima
• Inventors: Nakajima, Shozo
• Primary Examiner(s): SWANN III, GLEN R
• Application Number:
  US08/707,748
• Time in Patent Office: 677 Days
• Field of Search: 340/568, 340/571, 340/539, 340/693
• US Class Current: 340/571
• CPC Class Codes: G08B 13/1427 with transmitter-receiver for distance detection
• CPC Class Codes: G08B 21/0247 System arrangements wherein the alarm criteria uses signal strength
• CPC Class Codes: G08B 21/0286 Tampering or removal detection of the child unit from child or article

Abstract

An alarm system for preventing loss of personal property, comprises a pair of radio signal transmission/alarm units that each include a sending component having a signal oscillator, and a receiving/alarm component comprising a tuner for selecting a signal from the sending component and receiving the signal as an electrical current, an amplifier for amplifying the signal current, an alarm, and a switcher that switches off the alarm when the amplified signal current is above a prescribed level and switches on the alarm when the amplified signal current does not exceed a prescribed level. The signal transmitted by one sending component is tuned to the receiving/alarm component tuner frequency of the other transmission/alarm unit, and each receiving/alarm component is tuned to the signal frequency of the sending component in the other transmission/alarm unit.

Claims

1. An alarm system for preventing loss of personal property, comprising:

a pair of radio signal transmission/alarm units that each includes a sending component having a signal oscillator; and

a receiving/alarm component comprising a tuner for selecting a signal from the sending component and receiving the signal as an electrical current;

an amplifier for amplifying the signal current;

an alarm; and

a switcher that switches off the alarm when the amplified signal current is above a prescribed level and switches on the alarm when the amplified signal current does not exceed a prescribed level;

wherein the signal of each sending component is tuned to the receiving/alarm component tuner of the other transmission/alarm unit, and each receiving/alarm component is tuned to the signal of the sending component of the other transmission/alarm unit.

2. An alarm system according to claim 1 wherein one or both transmission/alarm units is a size and shape of a credit card.