NOVELTY - The device has a disk-shaped rotor (30) including a set of permanent magnets, two disk-shaped stators (10) including two electromagnetic coils and a clearance control mechanism (15) shifting the stators and the rotor to change size of a clearance formed among the stators and the rotor. A pair of analog magnetic sensors (16A, 26B) detects a phase of the permanent magnets. The magnetic sensors are provided at a specific position to keep a positional relation to the permanent magnets unchanged regardless of the size of the clearance.    USE - Electric motor device e.g. brushless motor such as two-phase brushless motor, for use as a generator to regenerate electric power in an electronic apparatus e.g. moving body such as rail car and electrically powered bicycle or power assisted bicycle, projector, cell phone such as fuel cell type mobile phone, and robot (all claimed). Can also be used for single-phase brushless motor, multi-phase brushless motor i.e. three-phase brushless motor, direct current (DC) motor, vibrating motor, spindle motor for optical storage device, magnetic storage device and polygon mirror drive, and fan motor for digital display device, vehicle on-board device, fuel cell type personal computer (PC), fuel cell type digital camera and fuel cell type video camera, and for actuator, clock, drum type washing machine and jet coaster.    ADVANTAGE - The device allows changing the size of the clearance formed among the stators and the rotor to vary density of a magnetic flux passing through the coils and change a back electromotive force (EMF) generated in the coils, thus enabling a change in torque or a change in rotation speed of the device without increasing applied voltage. The device is actuated by application of voltage with waveform similar to that of back EMF, thus improving motor efficiency and reducing generation of vibration and noise in the device.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for an electronic apparatus comprising a driven member driven by an electric motor device.    DESCRIPTION OF DRAWING(S) - The drawing shows a sectional view of a motor main body.    Disk-shaped stators (10)    Board (13)    Clearance control mechanism (15)    Analog magnetic sensors (16A, 26B)    Disk-shaped rotor (30)