| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To prevent problems caused by the use of radio communication in a security system where a glass breakage detection device radio-transmits a signal indicating glass breakage to an alarm device. <P>SOLUTION: The glass breakage detection device, when a glass is broken to cause a "Hi" output of a built-in comparator (S120: YES), transmits frame signals indicating the glass breakage at transmission frequencies "f1" (S160), then transmits frame signals at transmission frequencies "f2" (S180) and waits for an idle period set for each window glass (S200). The set is repeated until a prescribed time is reached (S210), and then only frame signals of the transmission frequency "f2" are transmitted (S230). Even if a radio wave interfering with the frame signals is transmitted, the alarm device can create an alarming action to suppress radio interference outside the system. A simulated signal switch is also provided to ground an input point of the comparator. <P>COPYRIGHT: (C)2004,JPO</p> |
