| 摘要 |
PURPOSE:To check the humidity condition inside a humidity proofing package by incorporating a humidity sensor into an oscillation circuit to monitor variations in the reference pulse and the measuring pulse obtained from the oscillation circuit. CONSTITUTION:A humidity sensor 1 is incorporated into an RC oscillation circuit to form a pulse generator 7, which generates a measuring pulse varying in the pulse frequency in proportion to changes in the resistance value of the humidity sensor 1. A reference pulse generation circuit 8 is built with a charging/discharging circuit comprising a resistance and a capacitor. The input terminal of the pulse generation circuit 8 is connected to the output terminal of the pulse generator 7 through a NOT gate 9 and the output terminals of both the pulse generation circuits 7 and 8 are connected to the input terminal of a NAND gate 10. As with a rise in the humidity in the package, the repetition frequency of the pulse generation circuit 7 heightens, the pulse width decreases so that the rising of the pulse coincides with the rising of the reference pulse from the reference pulse generation circuit 8. This state is memorized into a memory circuit 13 while a piezo-electric buzzer 16 sounds at the pulse oscillation cycle of the pulse generator 7. |
