Information input device, image forming apparatus, position determination method, and position determination program

A position determination method in which a computer determines an operated position on a touch panel of an information input device including the computer, to which operations information is input through operations on the touch panel, the information input device further including a display screen to display operations information integrated with a sensor unit in the touch panel, the sensor unit including plural sensors to measure a capacitance at a front surface of the display screen, the plural sensors being staggered such that three of the plural sensors adjacent to each other are arranged at positions corresponding to apices of a regular triangle, the method comprising:

• determining that the display screen is touched and the operations information is input when one of the sensors detects a level of the capacitance greater than or equal to a threshold level;
• comparing the levels of the capacitances detected with two adjacent sensors with the threshold level relative to the one sensor that detects the level of the capacitance greater than or equal to the threshold level;
• and
• determining the touched position on the display screen in accordance with the level of the capacitance detected with the one sensor and the levels of the capacitances detected with the two adjacent sensors based on a comparison result in said comparing, the levels of capacitances detected being associated with one of a plurality of predefined areas of a region formed by the three adjacent sensors to determine the touched position, each of the predefined areas being defined by respective capacitance detection levels for the three adjacent sensors.