| 摘要 |
PURPOSE:To make the device small-sized and to reduce the current consumption, by using a C-MOS ring oscillator, where a pressure detecting element having the pressure-resistance conversion characteristic is used as a feedback resistance, to convert the pressure value to a digital value. CONSTITUTION:When water pressure is applied to a diaphragm 10 in water, the diaphragm 10 is displaced, and the electric resistance of a pressure sensor 9 is changed. A water pressure detector 25 has the pressure sensor 9 as a detecting element and includes an operation block 39, which converts the water pressure to a depth of water, and consists of a C-MOS ring oscillator 34 using the pressure sensor 9 as the feedback resistance, a programmable divider 36, a counter 37, a latch circuit 38, etc. The C-MOS ring oscillator 34 consists of a capacitor 41, a current limiting resistance 42, a C-MOS NAND circuit 43, and C-MOS inverters 44 and 45 besides the pressure sensor 9, and the C-MOS ring oscillator 34 converts the pressure, namely, the change of the resistance value to a digital value finally. |
