Abstract: A level. A projected plane is generated substantially parallel to a reference plane by a light source rotatably emitting light. A main shaft, having a rotary portion and a pair of protrusions and connecting to the light source, is perpendicular to the projected plane. A universal joint is disposed in a housing with the main shaft rotatably passing therethrough. A level sensor detects inclination of the projected plane deviated from the reference plane and outputs an adjustment signal. An adjustment mechanism has a first movable member and a second movable member crossing each other. The first movable member impels one protrusion along a first axis, and the second movable member impels one protrusion along a second axis perpendicular to the first axis according to the adjustment signal. The main shaft is rotated around the universal joint until perpendicular to the reference plane with the projected plane parallel thereto.

Abstract: A level. A projected plane is generated substantially parallel to a reference plane by a light source rotatably emitting light. A main shaft, having a rotary portion and a pair of protrusions and connecting to the light source, is perpendicular to the projected plane. A universal joint is disposed in a housing with the main shaft rotatably passing therethrough. A level sensor detects inclination of the projected plane deviated from the reference plane and outputs an adjustment signal. An adjustment mechanism has a first movable member and a second movable member crossing each other. The first movable member impels one protrusion along a first axis, and the second movable member impels one protrusion along a second axis perpendicular to the first axis according to the adjustment signal. The main shaft is rotated around the universal joint until perpendicular to the reference plane with the projected plane parallel thereto.