Capacitance detection area sensor and conductive pattern sensing apparatus having capacitance detection area sensor

A capacitance detection area sensor, comprising:

• a capacitance detection area sensor circuit including a plurality of capacitance sensor elements arranged in a two-dimensional array, each of the capacitance sensor elements including a sensor electrode configured to, when capacitively coupled with a detection target having an electrical charge, detect an electrical charge in accordance with a change in a capacitance, a storage element configured to store an electrical charge of the sensor electrode, and a reset element configured to reset the storage element;
• a sensor element selection circuit configured to select a capacitance sensor element to be capacitively coupled sequentially from the capacitance detection area sensor circuit in order of rows or columns;
• a reading circuit configured to acquire a first signal at a first potential and a second signal at a second potential different from the first potential, from the selected capacitance sensor;
• a first signal storage circuit arranged for each column to store the read-out first signal;
• a second signal storage circuit arrange for each column to store the read-out second signal;
• a differential signal generating circuit configured to calculate a difference between the stored first signal and the stored second signal to generate a differential signal;
• an image processing circuit configured to generate an image representing a shape of the detection target based on a level of the differential signal from the differential signal generating circuit;
• and
• a controller configured to open the reset element of the capacitance detection area sensor circuit after bringing the reset element into conduction for each one of the rows selected from among the two-dimensional array to reset the storage element to set a potential of the sensor electrode to a reference value;
• acquire the first signal to store the first signal in the first signal storage circuit;
• after a predetermined period of time, acquire the second signal to store the second signal in the second signal storage circuit;
• and, after a predetermined period of time, calculate a differential signal of the first signal read from the first signal storage circuit and the second signal read from the second signal storage circuit.