Electrostatic type micro transducer and control system using the same

An electrostatic type micro transducer comprising,

• a plate shaped movable electrode made of monocrystalline silicon;
• a first substrate of the same material as said plate shaped movable electrode surrounding the plate shaped movable electrode;
• means for connecting said plate shaped movable electrode with said first substrate, said connecting means elastically supporting said plate shaded movable electrode;
• a first stationary electrode facing one major surface of said plate shaped movable electrode with a predetermined gap;
• and
• first members made of an electrical insulator material provided on the possible contacting portions of said plate shaped movable electrode;
• means for preventing sticking of said plate shaped movable electrode to said first stationary electrode through said first members due to at least one of residual dielectric polarization, residual electric charges and water located around possible contacting portions between said plate shaped movable electrode and said first stationary electrode, when said plate shaped movable electrode excessively displaces, further comprising,
• a first insulator substrate carrying said first stationary electrode;
• and
• wherein said sticking preventing means comprises means for reducing water adsorption and condensation around the possible contacting portions to prevent sticking caused by said first members.

An electrostatic type micro transducer comprising,

• a plate shaped movable electrode made of monocrystalline silicon;
• a first substrate of the same material as said plate shaped movable electrode surrounding the plate shaded movable electrode;
• means for connecting said plate shaped movable electrode with said first substrate, said connecting means elastically supporting said plate shaped movable electrode;
• a first stationary, electrode facing one major surface of said plate shaped movable electrode with a predetermined gap;
• and
• first members made of an electrical insulator material provided on the possible contacting portions of said plate shaped movable electrode;
• means for preventing sticking of said plate shaped movable electrode to said first stationary electrode through said first members due to at least one of residual dielectric polarization, residual electric charges and water located around possible contacting portions between said plate shaped movable electrode and said first stationary electrode, when said plate shaped movable electrode excessively displaces, further comprising,
• a first insulator substrate carrying said first stationary electrode thereon;
• and
• wherein said sticking preventing means comprises a combination of means for reducing electric fields induced around the possible contacting portions and means for reducing water adsorption and condensation around the possible contacting portions to prevent sticking caused by said first members.

An electrostatic type micro transducer comprising,

• a plate shaped movable electrode made of monocrystalline silicon;
• a first substrate of the same material as said plate shaped movable electrode surrounding the plate shaped movable electrode;
• means for connecting said plate shaped movable electrode with said first substrate, said connecting means elastically supporting said plate shaped movable electrode;
• a first stationary electrode facing one major surface of said plate shaped movable electrode with a predetermined gap;
• and
• means for preventing sticking of said plate shaped movable electrode to said first stationary electrode due to at least one of residual dielectric polarization, residual electric charges and water located around possible contacting portions between said plate shaped movable electrode and said first stationary electrode, when said plate shaped movable electrode excessively displaces, further comprising,
• a first insulator substrate carrying said first stationary electrode thereon, wherein said sticking preventing means includes means for limiting contacting area between said plate shaped movable electrode and said first stationary electrode in a form of insulator protrusions formed either on one surface of said plate shaped movable electrode or on the surface of said first stationary electrode having one of configurations of pyramid, truncated pyramid, circular cone, truncated circular cone, semi-sphere and laid down triangular prism of which a ridge runs parallel to the axis of said supporting means.

An electrostatic type micro transducer comprising,

• a plate shaped movable electrode made of monocrystalline silicon;
• a first substrate of the same material as said plate shaped movable electrode surrounding the plate shaped movable electrode;
• means for connecting said plate shaped movable electrode with said first substrate, said connecting means elastically supporting said plate shaped movable electrode;
• a first stationary electrode facing one major surface of said plate shaped movable electrode with a predetermined gap;
• and
• first members made of an electrical insulator material formed on at least one of the one surface of said plate shaped movable electrode and on the surface of said first stationary electrode at the possible contacting portions;
• means for preventing sticking of said plate shaped movable electrode to said first stationary electrode through said first members due to at least one of residual dielectric polarization, residual electric charges and water located around possible contacting portions between said plate shaped movable electrode and said first stationary electrode, when said plate shaped movable electrode excessively displaces, further comprising,
• a first insulator substrate carrying said first stationary electrode thereon;
• wherein said sticking preventing means includes means for limiting contacting area between said plate shaped movable electrode and said first stationary electrode in a form of a roughened surface formed on the surfaces opposing said first members.

An electrostatic type micro transducer comprising,

• a plate shaped movable electrode made of monocrystalline silicon;
• a first substrate of the same material as said plate shaped movable electrode surrounding the plate shaped movable electrode;
• means for connecting said plate shaped movable electrode with said first substrate, said connecting means elastically supporting said plate shaped movable electrode;
• a first stationary electrode facing one major surface of said plate shaped movable electrode with a predetermined gap;
• and
• means for preventing sticking of said plate shaped movable electrode to said first stationary electrode due to at least one of residual dielectric polarization, residual electric charges and water located around possible contacting portions between said plate shaded movable electrode and said first stationary electrode, when said plate shaped movable electrode excessively displaces, further comprising,
• a first insulator substrate carrying said first stationary electrode thereon, wherein said sticking preventing means includes a combination of means for reducing electric fields induced at the possible contacting portions and means for limiting contacting area between said plate shaped movable electrode and said first stationary electrode in a form of insulator protrusions formed on at least one of the one surface of said plate shaped movable electrode and on the surface of said first stationary electrode at possible contacting portions.

An electrostatic type micro transducer comprising,

• a plate shaped movable electrode made of monocrystalline silicon;
• a first substrate of the same material as said plate shaped movable electrode surrounding the plate shaped movable electrode;
• means for connecting said plate shaped movable electrode with said first substrate, said connecting means elastically supporting said plate shaped movable electrode;
• a first stationary electrode facing one major surface of said plate shaped movable electrode with a predetermined gap;
• and
• means for preventing sticking of said plate shaped movable electrode to said first stationary electrode due to at least one of residual dielectric polarization, residual electric charges and water located around possible contacting portions between said plate shaped movable electrode and said first stationary electrode, when said plate shaped movable electrode excessively displaces, further comprising,
• a first insulator substrate carrying said first stationary electrode thereon;
• and
• first members made of an electrical insulator material formed on at least one of the one surface of said plate shaped movable electrode and on the surface of said first stationary electrode at the possible contacting portions, wherein said sticking preventing means includes a combination of means for reducing electric fields induced at the possible contacting portions of the first members and means for limiting contact area between said plate shaped movable electrode and said first stationary electrode in a form of roughened surfaces formed on the surface opposing said first members.

An electrostatic type micro transducer comprising,

• a plate shaped movable electrode made of monocrystalline silicon;
• a first substrate of the same material as said plate shaped movable electrode surrounding the plate shaped movable electrode;
• means for connecting said plate shaped movable electrode with said first substrate, said connecting means elastically supporting said plate shaped movable electrode;
• a first stationary electrode facing one major surface of said plate shaped movable electrode with a predetermined gap;
• and
• first members provided on the possible contacting portions of said plate shaped movable electrode;
• means for preventing sticking of said plate shaped movable electrode to said first stationary electrode through said first members due to at least one of residual dielectric polarization, residual electric charges and water located around possible contacting portions between said plate shaped movable electrode and said first stationary electrode, when said plate shaped movable electrode excessively displaces, further comprising,
• a second stationary electrode facing the other major surface of said plate shaped movable electrode with a predetermined gap;
• further means for preventing sticking of said plate shaped movable electrode with said second stationary electrode caused by said first members due to at least one of residual dielectric polarization, residual electric charges and water around possible contacting portions between said plate shaped movable electrode and said second stationary electrode when said plate shaped movable electrode excessively displaces;
• a first insulator substrate carrying said first stationary electrode thereon;
• a second insulator substrate carrying said second stationary electrode thereon.

An electrostatic type micro transducer comprising,

• a plate shaped movable electrode made of monocrystalline silicon;
• a first substrate of the same material as said plate shaped movable electrode surrounding the plate shaped movable electrode;
• means for connecting said plate shaped movable electrode with said first substrate, said connecting means elastically supporting said plate shaped movable electrode;
• a first stationary electrode facing one major surface of said plate shaped movable electrode with a predetermined gap;
• and
• means for preventing sticking of said plate shaped movable electrode to said first stationary electrode due to at least one of residual dielectric polarization, residual electric charges and water located around possible contacting portions between said plate shaped movable electrode and said first stationary electrode, when said plate shaped movable electrode excessively displaces;
• a second stationary electrode facing the other major surface of said plate shaped movable electrode with a predetermined gap;
• further means for prevent sticking of said plate shaped movable electrode with said second stationary electrode due to at least one of residual dielectric polarization, residual electric charges and water around possible contacting portions between said plate shaped movable electrode and said second stationary electrode when said plate shaped movable electrode excessively displaces;
• wherein said first and second stationary electrodes are respectively made of monocrystalline silicon and, further comprising a first insulating layer disposed between said first stationary electrode and said first substrate, and a second insulating layer disposed between said first substrate and said second stationary electrode, wherein said both sticking preventing means are means for limiting contacting area between said plate shaped movable electrode and said first and second stationary electrodes in a form of insulator protrusions formed on at least one of the surfaces of said plate shaped movable electrode and on the surfaces of said first and second stationary electrodes at the possible contacting portions having one of the configurations of pyramid, truncated pyramid, circular cone, truncated circular cone, semi-sphere and laid down triangular prism of which a ridge runs parallel to the axis of said supporting means.

A motor vehicle control system comprising,

• an electrostatic type micro accelerometer unit including a plate shaped movable electrode made of monocrystalline silicon;
• a first substrate of the same material as said plate shaped movable electrode surrounding the plate shaped movable electrode;
• means for connecting said plate shaped movable electrode with said first substrate, said connecting means elastically supporting said plate shaped movable electrode;
• a first stationary electrode facing one major surface of said plate shaped movable electrode with a predetermined gap;
• a stopper means for preventing mechanical contact between said plate shaped movable electrode and said first stationary electrode provided either on said plate shaped movable electrode or on said first stationary electrode at their possible contacting portions when said plate shaped movable electrode excessively displaces toward Said first stationary electrode;
• and means for preventing permanent sticking of said plate shaped movable electrode to said first stationary electrode through said stopper means due to at least one of residual dielectric polarization, residual electric charges and water located around the possible contacting portions between said plate shaped movable electrode and said first stationary electrode;
• and
• at least one of an anti-lock brake control unit;
• an active suspension control unit;
• a total spin control unit;
• a traction control unit;
• and an air bag control unit, wherein at least one of said anti-lock brake control unit, said active suspension control unit, said total spin control unit, said traction control unit and said air bag control unit performs a predetermined control based upon an output signal from said accelerometer.

An electrostatic accelerometer which determines an acceleration by detecting displacement of a pendulum mass comprising:

• a first member serving as the pendulum mass;
• a second member elastically supporting said first member;
• a third member disposed facing said first member via predetermined gap, wherein said first and third members are electrodes;
• a fourth member disposed either on said first member or on said third member at a mechanically contactable portion between said first and third members which is designed to prevent said first member from contacting to said third member,
• wherein the contactable area at the top end of said fourth member is selected smaller than the bottom area thereof whereby sticking of said first member to said third member via said fourth member is prevented.

An electrostatic type micro pressure sensor comprising:

• a movable electrode in a form of diaphragm, formed on one of the major surfaces of which a pressure to be detected is designed to be applied;
• a stationary electrode disposed facing the other major surface of said movable electrode via a predetermined gap;
• and
• an insulator protrusion disposed either on said movable electrode or on said stationary electrode at a mechanically contactable portion between said movable and stationary electrodes which is designed to prevent said movable electrode from sticking to said stationary electrode, wherein the contactable area at the top end of said insulator protrusion is selected smaller than the bottom area thereof to prevent sticking caused by the insulator protrusion.

An electrostatic type micro valve actuator comprising:

• a movable electrode in a form of diaphragm serving as a movable valve;
• a stationary electrode serving as a stationary valve having an orifice supported on an insulator substrate and disposed facing said movable electrode, a part of said stationary electrode facing said movable electrode is removed at their possible contacting portions when a predetermined voltage is applied between said movable and stationary electrodes exposing the surface of said insulator substrate;
• and
• an insulator protrusion formed either on the exposed surface of said insulator substrate or on the surface of said movable electrode facing the exposed surface of said insulator substrate and having a height which prevents direct contact between said movable and stationary electrodes.

An electrostatic type micro transducer comprising:

• a movable electrode made of silicon;
• a substrate made of silicon for supporting said movable electrode via an elastic connecting means;
• a stationary electrode facing one major surface of said movable electrode with a predetermined gap;
• a stopper means for preventing mechanical contact between said movable electrode and said stationary electrode provided either on said movable electrode or on said stationary electrode at their possible contacting portions when said movable electrode excessively displaces toward said stationary electrode, said stopper means being configurated in a form of protrusion having a smaller top contactable area than the bottom thereof whereby permanent sticking of said movable electrode to said stationary electrode caused by said stopper means is prevented.

An electrostatic microactuator:

• a first member serving as a movable mass;
• a second member elastically supporting said first member;
• a third member disposed facing said first member via a predetermined gap, wherein said first and third members are electrodes;
• a fourth member disposed either on said first member or on said third member at a mechanically contactable portion between said first and third members which is designed to prevent said first member from contacting to said third member, wherein the contactable area at the top end of said fourth member is selected smaller than the bottom area thereof whereby sticking of said first member to said third member via said fourth member is prevented.