WE CLAIM:
1. An operation input device comprising:
a knob for operations, disposed in a display region of a touch display;
a plurality of conductor columns provided in the knob;
a touch point detecting unit for detecting a touch point corresponding to at least one of the conductor columns;
a location determining unit for determining a location of the at least one of the conductor columns, using a result of the detection by the touch point detecting unit; and
a location estimating unit for estimating, when there is a conductor column that has not been detected as a touch point by the touch point detecting unit, a location of the conductor column that has not been detected as a touch point by the touch point detecting unit, using positional relationship information indicating a positional relationship between the plurality of conductor columns in the knob and location history information indicating a history of locations of the respective plurality of conductor columns.
2. The operation input device according to claim 1, wherein the location estimating unit estimates a location of a conductor column that has not been detected as a touch point by the touch point detecting unit in a state in which the knob is not being touched with user's fingers.
3. An operation input device comprising:
a knob for operations, disposed in a display region of a touch display; a plurality of conductor columns provided in the knob and including a first conductor column that can be detected as a touch point regardless of whether or not the

knob is in a state of being touched with user's fingers, and a second conductor column that can be detected as a touch point only in a state in which the knob is being touched with the user's fingers;
a touch point detecting unit for detecting a touch point corresponding to the first conductor column in a state in which the knob is not being touched with the user's fingers;
a location determining unit for determining a location of the first conductor column, using a result of the detection by the touch point detecting unit in the state in which the knob is not being touched with the user's fingers; and
a location estimating unit for estimating a location of the second conductor column, using positional relationship information indicating a positional relationship between the plurality of conductor columns in the knob and location history information indicating a history of locations of the respective plurality of conductor columns, in the state in which the knob is not being touched with the user's fingers.
4. The operation input device according to claim 3, wherein
the touch point detecting unit detects touch points corresponding to the first conductor column and the second conductor column in the state in which the knob is being touched with the user's fingers, and
the location determining unit determines locations of the first conductor column and the second conductor column, using results of the detection by the touch point detecting unit in the state in which the knob is being touched with the user's fingers.
5. An operation input device comprising:

a knob for operations, disposed in a display region of a touch display;
a plurality of conductor columns provided in the knob;
a touch point detecting unit for detecting touch points corresponding to the plurality of conductor columns in a first operating mode in a state in which the knob is being touched with user's fingers, and detecting touch points corresponding to the plurality of conductor columns in a second operating mode in a state in which the knob is not being touched with the user's fingers, the second operating mode being higher in detection sensitivity than the first operating mode;
a location determining unit for determining locations of the respective plurality of conductor columns, using results of the detection obtained in the first operating mode, in the state in which the knob is being touched with the user's fingers; and
a location estimating unit for estimating locations of the respective plurality of conductor columns, using results of the detection obtained in the second operating mode, in the state in which the knob is not being touched with the user's fingers.
6. The operation input device according to claim 5, wherein in the first operating mode, each of the plurality of conductor columns is detected as a single touch point, and in the second operating mode, two or more conductor columns are collectively detected as a single touch point, the two or more conductor columns being some of the plurality of conductor columns.
7. The operation input device according to any one of claims 1 to 4, wherein each location indicated by the location history information is a location determined in past by the location determining unit or a location estimated in past by the location estimating unit.

8. The operation input device according to any one of claims 2 to 6, comprising a
finger-touch-on-the-knob determining unit for determining whether the knob is in a state of being touched with the user's fingers.