WARNING SYSTEM

• US 3,771,154 A
• Filed: 12/27/1971
• Issued: 11/06/1973
• Est. Priority Date: 12/30/1970
• Status: Expired due to Term

• Current Assignee: Masayoshi Takei
• Original Assignee: Masayoshi Takei
• Inventors: Takei, Masayoshi
• Primary Examiner(s): Caldwell, John W.
• Assistant Examiner(s): Wannisky, William M.
• Application Number:
  US05/212,063
• Time in Patent Office: 680 Days
• Field of Search: 340/274,275,309.1,309.5,276 200/61.62 355/205
• US Class Current: 340/686.1
• CPC Class Codes: G08B 13/08 by opening, e.g. of door, of window, of drawer, of shutter, of curtain, of blind

Abstract

A warning system and apparatus includes a circuit for receiving a signal which is indicative of an abnormal condition and a power source for operating and maintaining a circuit to indicate the abnormal condition. A magnetic switch is used in sensing the existance of abnormal conditions. Thus, the magnetic switch serves as a sensor for detecting non-standard or alarm conditions at the site where the warning apparatus is installed. A transistorized circuit operates to trigger the alarm and also, under certain circumstances, to delay the alarm signal during a predetermined time interval after the magnetic switch is actuated to avoid undesired indications or false alarm. Also, the system operates to maintain the alarm even after the abnormal condition which set off the alarm has returned to its normal state.

Claims

1. A warning system for emitting a warning signal upon change in position of an actuating member, comprising a sensing circuit in which a magnetic switch means and a capacitor means is included, said magnetic switch means being operable in response to a change in position of said actuating member to activate said sensing circuit, said capacitor means being charged during initial activation of said sensing circuit, a thyristor means triggered by said sensing curcuit to provide a signal after a predetermined period measured from the time said sensing circuit is activated by said change in position of said actuating member to the time said capacitor means becomes charged, said sensing circuit further including a first transistor with base-emitter circuit connected in parallel with said capacitor means, a second transistor with a base connected to the collector of said first transistor and a third transistor with collector connected to the gate of said thyristor means, the emitter of said third transistor being connected to the anode of said thyristor means, a flip-flop circuit responsive to the signal produced by said thyristor means and operable to provide an alarm signal, and alarm means receiving said alarm signal, said thyristor means being operable to sustain its signal and provide actuation of said alarm means even though said actuating member has returned to its initial position.