US Patent 7934322 Digital protractor

A digital protractor for measuring angular displacement from a referenced surface includes a substantially congruent pair of pivotally interconnected upper and lower arms, which arms are superposable upon one another. Each arm has a pair of substantially parallel engagement edges extending longitudinally of the arm. One of the arms is engagable along an engagement edge thereof with the reference surface. A capacitive sensor is secured to the lower arm and a digital readout device is secured to the upper arm for operatively cooperating with the capacitive sensor to measure and display the angular displacement from the arm engaging the reference surface to the other arm.