Adjusting operating characteristics of micromachined torsional oscillators

In an integrated, micromachined structure that includes:

• a frame-shaped reference member;
• a first pair of diametrically opposed, axially aligned torsion bars projecting from the reference member;
• a first, frame-shaped first dynamic member that is coupled by the first torsion bars to the reference member to be thereby supported from the reference member for rotation about an axis of the first torsion bars;
• a second pair of diametrically opposed, axially aligned torsion bars projecting from the first dynamic member;
• a second dynamic member that is coupled by the second torsion bars to the first dynamic member to be thereby supported from the first dynamic member for rotation about an axis of the second torsion bars;
• the reference member, the first and second torsion bars and the first and second dynamic members being all monolithically fabricated from a stress-free semiconductor layer of a silicon substrate;
• the first and second dynamic members thus supported within the reference member respectively by the first and second torsion bars each respectively exhibiting a plurality of vibrational modes including a principal torsional vibrational mode about the axis of the torsion bars, a vertical shaking vibrational mode, a vertical rocking vibrational mode, a lateral shaking vibrational mode, and a lateral rocking vibrational mode, each such vibrational mode of the dynamic member having characteristics including a vibrational frequency and a Q;
• and
• drive means for imparting oscillatory motion to the second dynamic member about the axis of the second torsion bars;
• wherein the improvement comprises:
• characteristic adjusting means for tailoring a characteristic of the principal torsional vibrational mode of the second dynamic member by controlling a characteristic of the first dynamic member.

An integrated, micromachined structure comprising:

• a frame-shaped reference member;
• a first pair of diametrically opposed, axially aligned torsion bars projecting from the reference member;
• a first, frame-shaped first dynamic member that is coupled by the first torsion bars to the reference member to be thereby supported from the reference member for rotation about an axis of the first torsion bars, the first dynamic member having a thickness substantially the same as that of the first pair of torsion bars;
• a second pair of diametrically opposed, axially aligned torsion bars projecting from the first dynamic member;
• a second dynamic member that is coupled by the second torsion bars to the first dynamic member to be thereby supported from the first dynamic member for rotation about an axis of the second torsion bars;
• the reference member, the first and second torsion bars and the first and second dynamic members being all monolithically fabricated from a stress-free semiconductor layer of a silicon substrate;
• and
• drive means for imparting oscillatory motion to the second dynamic member about the axis of the second torsion bars.

An integrated, micromachined structure comprising:

• a frame-shaped reference member;
• a first pair of diametrically opposed, axially aligned torsion bars projecting from the reference member;
• a first, frame-shaped first dynamic member that is coupled by the first torsion bars to the reference member to be thereby supported from the reference member for rotation about an axis of the first torsion bars, the first dynamic member having a thickness that is only slightly greater than that of the first pair of torsion bars;
• a second pair of diametrically opposed, axially aligned torsion bars projecting from the first dynamic member;
• a second dynamic member that is coupled by the second torsion bars to the first dynamic member to be thereby supported from the first dynamic member for rotation about an axis of the second torsion bars;
• the reference member, the first and second torsion bars and the first and second dynamic members being all monolithically fabricated from a stress-free semiconductor layer of a silicon substrate;
• and
• drive means for imparting oscillatory motion to the second dynamic member about the axis of the second torsion bars.

In an integrated, micromachined structure that includes:

• a frame-shaped reference member;
• a pair of diametrically opposed, axially aligned torsion bars projecting from the reference member;
• a dynamic member that is coupled by the torsion bars to the reference member to be thereby supported from the reference member for rotation about an axis of the torsion bars;
• the reference member, the torsion bars and the dynamic member all monolithically fabricated from a stress-free semiconductor layer of a silicon substrate;
• the dynamic member thus supported within the reference member by the torsion bars exhibiting a plurality of vibrational modes including a principal torsional vibrational mode about the axis of the torsion bars, a vertical shaking vibrational mode, a vertical rocking vibrational mode, a lateral shaking vibrational mode, and a lateral rocking vibrational mode, each such vibrational mode of the dynamic member having characteristics including a vibrational frequency and a Q;
• drive means for imparting oscillatory motion to the dynamic member about the axis of the torsion bars;
• and
• a gas-filled hermetic enclosure that envelopes the reference member, the torsion bars, the dynamic member and at least a portion of the drive means, the gas which fills the hermetic enclosure having a composition different from that of an atmosphere that surrounds the hermetic enclosure.

In an integrated, micromachined structure that includes:

• a frame-shaped reference member;
• a pair of diametrically opposed, axially aligned torsion bars projecting from the reference member;
• a dynamic member that is coupled by the torsion bars to the reference member to be thereby supported from the reference member for rotation about an axis of the torsion bars;
• the reference member, the torsion bars and the dynamic member all monolithically fabricated from a stress-free semiconductor layer of a silicon substrate;
• the dynamic member thus supported within the reference member by the torsion bars exhibiting a plurality of vibrational modes including a principal torsional vibrational mode about the axis of the torsion bars, a vertical shaking vibrational mode, a vertical rocking vibrational mode, a lateral shaking vibrational mode, and a lateral rocking vibrational mode, each such vibrational mode of the dynamic member having characteristics including a vibrational frequency and a Q;
• and
• drive means for imparting oscillatory motion to the dynamic member about the axis of the torsion bars;
• wherein the improvement comprises:
• characteristic adjusting means for tailoring a characteristic of the principal torsional vibrational mode of the dynamic member by altering the dynamic member.

In an integrated, micromachined structure that includes:

• a frame-shaped reference member;
• a pair of diametrically opposed, axially aligned torsion bars projecting from the reference member;
• a dynamic member that is coupled by the torsion bars to the reference member to be thereby supported from the reference member for rotation about an axis of the torsion bars;
• the reference member, the torsion bars and the dynamic member all monolithically fabricated from a stress-free semiconductor layer of a silicon substrate;
• the dynamic member thus supported within the reference member by the torsion bars exhibiting a plurality of vibrational modes including a principal torsional vibrational mode about the axis of the torsion bars, a vertical shaking vibrational mode, a vertical rocking vibrational mode, a lateral shaking vibrational mode, and a lateral rocking vibrational mode, each such vibrational mode of the dynamic member having characteristics including a vibrational frequency and a Q;
• and
• drive means for imparting oscillatory motion to the dynamic member about the axis of the torsion bars;
• wherein the improvement comprises:
• characteristic adjusting means added to the micromachined structure to mechanically tailor the frequency of the principal torsional vibrational mode of the dynamic member.