Abstract: A spectrum control device includes a control unit that obtains spectrum information. The control unit controls at least one of a spectrum of light emitted by a light emitting device or a spectrum of image light that forms an image, on the basis of the spectrum information.

Abstract: A spectrum control device includes a control unit that obtains spectrum information. The control unit controls at least one of a spectrum of light emitted by a light emitting device or a spectrum of image light that forms an image, on the basis of the spectrum information.

Abstract: An apparatus that corrects a weight imbalance around an axis of a spindle motor that rotates a disc in a disc drive includes an impact applicator that applies an impact to a housing that houses the spindle motor and the disc, a plate that supports the housing and impact applicator, a spring member that supports the plate, and enables the plate and the housing to vibrate together when the spindle motor rotates, and a detector that detects a vibration of the housing when the spindle motor rotates.

Abstract: A balance correction apparatus is configured to correct weight imbalance around an axis of a spindle motor, and includes a piezoelectric actuator configured to apply an impact to a housing, a controller configured to generate as a rectangular wave a force profile that represents an acceleration applied to the housing by the piezoelectric actuator, and a waveform generator configured to generate a voltage waveform configured to drive the piezoelectric actuator, by integrating the force profile twice. The rectangular wave has a first acceleration after a leading edge and a second acceleration after a trailing edge. The first acceleration enables the disc to move relative to the spindle motor and the housing. The second acceleration enables the disc to move together with the spindle motor and the housing.

Abstract: An apparatus that corrects a weight imbalance around an axis of a spindle motor that rotates a disc in a disc drive includes an impact applicator that applies an impact to a housing that houses the spindle motor and the disc, a plate that supports the housing and impact applicator, a spring member that supports the plate, and enables the plate and the housing to vibrate together when the spindle motor rotates, and a detector that detects a vibration of the housing when the spindle motor rotates.

Abstract: A gas injection valve of a gas engine includes a valve body having a nozzle chamber with nozzle holes for injecting fuel gas, a first gas passage for introducing fuel gas, and a second gas passage communicable at one end to the first gas passage and at the other end to the nozzle chamber. A first needle valve closes and opens communication between the first and second gas passages. A second needle valve closes and opens communication between the second gas passage and the nozzle chamber. The first and second needle valves are urged in the closing direction thereof. A hydraulic actuator opens the two needle valves. An extreme tip of the first needle valve in closed state is disposed within and exposed to the interior of the second gas passage.