Abstract: A first predetermined operation is performed when a contact detector detects contact with an operation knob. A time length of the contact thus detected by the contact detector is measured and it is determined whether the time length of the contact is longer or shorter than a predetermined value. When it is determined that the time length of the contact is longer or shorter than the predetermined value, a second predetermined operation is performed.

Abstract: A membrane switch which can be opened and closed with a small pushing load. A fixed contact point 4 is formed on one surface of a first sheet 3. Flexible movable contact points 7 opposed to the fixed contact point 4 via a space in a manner movable to and way from the fixed contact point 4 are formed on one surface of a second sheet 6, opposed to the one surface of the first sheet 3. Insulators are arranged on the flexible movable contact points at locations except for the locations of push portions of the flexible movable contact points 7.

Abstract: A membrane switch which can be opened and closed with a small pushing load. A fixed contact point 4 is formed on one surface of a first sheet 3. Flexible movable contact points 7 opposed to the fixed contact point 4 via a space in a manner movable to and way from the fixed contact point 4 are formed on one surface of a second sheet 6, opposed to the one surface of the first sheet 3. Insulators are arranged on the flexible movable contact points at locations except for the locations of push portions of the flexible movable contact points 7.

Abstract: A pusher formed of a rubber material, a click plate, a membrane switch which serves as a second step switch, a reinforcing plate, a membrane sheet on which a plurality of first step switches are formed, a key operation base and a knob are sequentially assembled into a case. The knob includes a plurality of depressing pieces having on its internal surface a projection which moves into contact with each membrane switch and also includes a marginal portion which is supported by the top surface of the case. The knob is thin-walled except for the depressing piece, and the thin-walled portion comprises a thermoplastic elastomer or silicone rubber. The knob, the key operation base and the reinforcing plate are secured together. As the depressing piece is depressed, the thin-walled portion which is located therearound becomes flexed, whereby the membrane switch is depressed by the projection to turn the switch on.

Abstract: A pusher formed of a rubber material, a click plate, a membrane switch which serves as a second step switch, a reinforcing plate, a membrane sheet on which a plurality of first step switches are formed, a key operation base and a knob are sequentially assembled into a case. The knob includes a plurality of depressing pieces having on its internal surface a projection which moves into contact with each membrane switch and also includes a marginal portion which is supported by the top surface of the case. The knob is thin-walled except for the depressing piece, and the thin-walled portion comprises a thermoplastic elastomer or silicone rubber. The knob, the key operation base and the reinforcing plate are secured together. As the depressing piece is depressed, the thin-walled portion which is located therearound becomes flexed, whereby the membrane switch is depressed by the projection to turn the switch on.