A display device includes: a display monitor; a control board which drives the display monitor; a chassis which is provided between the display monitor and the control board. The speed change of the driven unit is expressed substantially as a positive half cycle of a sinusoidal waveform having an amplitude and a time duration, and the feed-forward target data is calculated from the amplitude and the time duration to represent a rectangular waveform approximating the positive half cycle of the sinusoidal waveform. The device also has an electrode electrically coupled to the modulator for applying the modulated waveform to the dermatomic region. An opening through which oil passes is provided in the main chamber rib only rearward of a rear edge of the oil suction port. With the reservation, the center transmits an abnormality transmission request to the vehicle.