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The pen set 2 contains a core 24 for writing and a second power supply module 26 to provide electric power required by the alarm 20. In this embodiment, the second power supply module 26 is a mercury battery. In addition, the alarm 20 contains a second lighting means 200, a buzzer 202 and a second switch 204 to set the alarm 20 ON and OFF. The second lighting means 200 generates a blinking signal when the radio signal waveform received by the radio receiver 22 is abnormal to alert users that the article carrying the radio transmitter 22 is spaced from the pen set 2 at a distance greater than the present range. Then the buzzer 202 is driven by the radio receiver 22 to generate an audio signal to alert the users that the article carrying the radio transmitter 1 is spaced from the pen set 2 at a distance greater than the present range.
It is to be noted that, in this embodiment the signal waveform (such as signal definition or signal power) transmitted between the radio transmitter 1 and the radio receiver 22 is used to determine whether the distance between the two is too much. In practice, whether the spaced distance is excessive can also be determined by a signal transmitted constantly from the radio transmitter 1 to the radio receiver 22.
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In short, the invention actuates the second lighting means 200 to generate blinking light and the buzzer 202 to generate an audio signal when the radio receiver 22 is spaced from the radio transmitter 1 at a distance greater than the preset range that affects the radio signal. Hence users are alerted by the carrying pen set 2 that the article containing the radio transmitter 1 is located too far away and an immediate action should be taken to prevent the article from getting lost. This invention contains novel functions and provides a significant improvement over the conventional techniques.
While the preferred embodiment of the invention has been set forth for the purpose of disclosure, modifications of the disclosed embodiment of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments which do not depart from the spirit and scope of the invention.