Capacitance-type external-force detecting device with improved sensitivity

An external force detecting device, comprising:

• n fixed electrodes supported by said substrate, n being an integer greater than 1;
• n moveable electrodes which are located at nominal positions relative to the fixed electrodes when they are at rest and being moveable in a detection direction in response to an external force applied thereto so as to vary the relative locations of the fixed and moveable electrodes;
• n/2 electrode pairs, each electrode pair including a respective fixed electrode and a respective moveable electrode that together define a variable capacitance whose capacitance varies as a function of the distance therefrom, the electrode pairs being divided into first and second sets of electrode pairs, the fixed and moveable electrodes of the first set of electrode pairs being spaced from one another by a first inter-electrode distance when the moveable electrodes are in their nominal positions, the fixed and moveable electrodes of a second set of electrode pairs being spaced from one another by a second inter-electrode distance when the moveable electrodes are in their nominal positions, the dimension ratio of the first inter-electrode distance to the second inter-electrode distance falling within the range of 1:2 to 1:5;
• and
• a detector for detecting the displacement of the moveable electrodes relative to the fixed electrodes as a function of the variation in the ratio of the overall capacitance of the first and second sets of electrode pairs resulting from movement of the moveable electrodes in response to an application of the external force.