Keyboard switch

Claim 2

A keyboard switch comprising: an insulating substrate; a first electrode laid on the insulating substrate; a second electrode facing the first electrode; a dielectric positioned between the first and second electrodes, said second electrode being formed of a conical coil spring, and being positioned on the dielectric such that one end portion of the spring may be contacted with the surface of the dielectric, capacitance between the first and second electrodes being mainly defined by the contact area between the dielectric and second electrode; a button, positioned on the other end portion of the second electrode, for compressing the second electrode toward the first electrode to change the contact area when the button depressed toward the first electrode, said capacitance varying with the change in the facing area which changes substantially in proportion to the depth of depression of the button; means for restoring said button to an undepressed position, said means for restoring comprising said second electrode; and means for giving snap feeling to an operator when the button is depressed sufficiently that the capacitance exceeds a given value sufficient to activate said switch, whereby the switch is capacitive-coupled for switching operation and the feeling is given to the operator when the capacitance exceeds the given value.

Claim 3

The keyboard switch according to claim 1, wherein said means for giving snap feeling include an elastic cap provided between the second electrode and button, and whereby said elastic cap is deformed to give the snap feeling to the operator when the button is depressed and the capacitance exceeds the given value.

Claim 4

The keyboard switch according to claim 2, wherein said elastic cap is formed of a rubber.

Claim 5

The keyboard switch according to claim 2, wherein said elastic cap includes a base member with an opening which opposes the first electrode, and a dome-shaped member attached to the base member to close the opening.

Claim 6

The keyboard switch according to claim 4, wherein said dome-shaped member has a thickness which is uneven in places.

Claim 7

The keyboard switch according to claim 5, wherein said dome-shaped member has a thin annular portion on the base member side and a thick annular portion on the top side.

Claim 8

The keyboard switch according to claim 5, wherein said dome-shaped member has a thick annular portion on the base member side and a thin annular portion on the top side.

Claim 9

The keyboard switch according to claim 7, wherein said dome-shaped member has a thick portion at the top thereof.

Claim 10

A keyboard switch comprising: an insulating substrate; a first electrode having one side and fixed on the insulating substrate; a second electrode having one side and fixed on the same plane with the first electrode on the insulating substrate, said one sides of the first and second electrodes facing each other; an auxiliary electrode formed of a conical coil spring, one end portion of the auxiliary electrode being mounted on the first and second electrodes; a dielectric positioned between the first and second electrodes and the auxiliary electrode, the capacitance of the keyboard switch being mainly defined by contact area between the dielectric and auxiliary electrode; a button, positioned on the other end portion of the auxiliary electrode, for compressing the auxiliary electrode toward the insulating substrate to change the contact area when the button is depressed toward the insulating substrate, said capacitance varying with the change in the facing area which changes substantially in proportion to the depth of depression of the button; means for restoring said button to an undepressed position, said means for restoring comprising said auxiliary electrode; and means for giving snap feeling to an operator when the button is depressed sufficiently that the capacitance exceeds a given value sufficient to activate said switch whereby the switch is capacitive-coupled for a switching operation and the snap feeling is given to the operator when the capacitance exceeds the given value.

Claim 11

A keyboard switch comprising: an insulating substrate; a first electrode having one side and fixed on the insulating substrate; a second electrode having one side and fixed on the same plane with the first electrode on the insulating substrate, said one sides of the first and second electrodes facing each other; an auxiliary electrode formed of a conical coil spring, one end portion of the auxiliary electrode being mounted on the first and second electrodes; a dielectric positioned between the first and second electrodes and the auxiliary electrode, the capacitance of the keyboard switch being mainly defined by contact area between the dielectric and auxiliary electrode; a button, positioned on the other end portion of the auxiliary electrode, for compressing the auxiliary electrode toward the insulating substrate to change the contact area when the button is depressed toward the insulating substrate, said capacitance varying with the change in the facing area which changes substantially in proportion to the depth of depression of the button; means for restoring said button to an undepressed position, said means for restoring comprising said auxiliary electrode; and means for giving snap feeling to an operator when the button is depressed sufficiently that the capacitance exceeds a given value sufficient to activate said switch whereby the switch is capacitive-coupled for a switching operation and the snap feeling is given to the operator when the capacitance exceeds the given value.

Claim 12

The keyboard switch according to claim 9, wherein said means for giving snap feeling include an elastic cap provided between the second electrode and button, whereby said elastic cap is deformed to give the snap feeling to the operator when the button is depressed and the capacitance exceeds the given value.

Claim 13

The keyboard switch according to claim 10, wherein said elastic cap is formed of a rubber.

Claim 14

The keyboard switch according to claim 10, wherein said elastic cap includes a base member with an opening which opposes the first electrode, and a dome-shaped member attached to the base member to close the opening.

Claim 15

The keyboard switch according to claim 12, wherein said dome-shaped member has a thickness which is uneven in places.

Claim 16

The keyboard switch according to claim 13, wherein said dome-shaped member has a thin annular portion on the base member side and a thick annular portion on the top side.

Claim 17

The keyboard switch according to claim 13, wherein said dome-shaped member has a thick annular portion on the base member side and a thin annular poriton on the top side.

Claim 18

The keyboard switch according to claim 15, wherein said dome-shaped member has a thick portion at the top thereof.