| 摘要 |
A miniature accelerometer is fabricated using integrated circuit manufacturing and silicon micromachining techniques to form a closed loop, force balance sensor utilizing a silicon proofmass 16 formed from and connected to a layer of silicon 24 by a split flexure 22 etched therein. Sensor circuitry 14 detects AC signals coupled from the proofmass to a pair of electrodes 30, 32 formed on glass layers 26, 26 anodically bonded to the silicon layer. A DC restorative force is applied to the electrodes 30, 32 in response to the detected AC signals to balance acceleration forces applied to the proofmass. The sensor design is highly symmetrical. The proofmass receives applied voltages from DC bias source 35 and AC source 38, the resultant signals on electrodes 30, 32 being fed to amplifier 60 via a diode quad bridge. The amplifier output signal, at point 34, is of magnitude and sign corresponding to the sensed acceleration and is fed back to the electrodes 30, 32 (via an inverter 62 in the latter case). Conductive guard bands 64, 66 are provided on the glass layers 26, 28 around the electrodes. To prevent the proofmass touching one of the electrodes if the device is under acceleration at start-up, the guard electrodes have inward fingers 74 - 77 corresponding to cut-outs in the electrodes, and contact posts are provided on the proofmass as at 78, 79, fig. 3. <IMAGE> |
