Set volume control device for on-vehicle audio system

A set volume control device for an on-vehicle audio system having a set volume changer for increasing and decreasing a set volume of the audio system, and capable of controlling the set volume changer to automatically control the set volume of the audio system according to vehicle speed, the device further comprising:

• a vehicle speed detector for detecting vehicle speed;
• a volume control switch to which a vehicle occupant can arbitrarily give an operational input;
• and
• a controller for controlling the set volume changer based on a vehicle speed detected by the vehicle speed detector and the operational input to the volume control switch so that the set volume of the audio system becomes a low vehicle speed region set volume fixed independently of vehicle speed change in a low vehicle speed region of an upper limit vehicle speed or less;
• becomes a high vehicle speed region set volume fixed independently of the vehicle speed change in a high vehicle speed region of a lower limit vehicle speed or more;
• and changes according to the vehicle speed change along a predetermined medium vehicle speed region set volume change line connecting the low vehicle speed region set volume and the high vehicle speed region set volume in a medium vehicle speed region between the low vehicle speed region and the high vehicle speed region,
• wherein the controller changes the low vehicle speed region set volume according to an operational input to the volume control switch within a first volume setting range set up in advance when the volume control switch is operated in the low vehicle speed region, and changes the high vehicle speed region set volume according to an operational input to the volume control switch within a second volume setting range set up in advance when the volume control switch is operated in the high vehicle speed region, and wherein a lower limit of the second volume setting range is set higher than an upper limit of the first volume setting range.