Abstract: An accelerometer or a seismometer using an in-plane suspension geometry having a suspension plate and at least one fixed capacitive plate. The suspension plate is formed from a single piece and includes an external frame, a pair of flexural elements, and an integrated proof mass between the flexures. The flexural elements allow the proof mass to move in the sensitive direction in the plane of suspension while restricting movement in all off-axis directions. Off-axis motion of the proof mass is minimized by the use of intermediate frames disbursed within and between the flexural elements. Intermediate frames can include motion stops to prevent further relative motion during overload conditions. The device can also include a dampening structure, such as a spring or gas structure that includes a trapezoidal piston and corresponding cylinder, to provide damping during non-powered states. The capacitive plate is made of insulating material.

Abstract: An accelerometer or a seismometer using an in-plane suspension geometry having a suspension plate and at least one fixed capacitive plate. The suspension plate is formed from a single piece and includes an external frame, a pair of flexural elements, and an integrated proof mass between the flexures. The flexural elements allow the proof mass to move in the sensitive direction in the plane of suspension while restricting movement in all off-axis directions. Off-axis motion of the proof mass is minimized by the use of intermediate frames disbursed within and between the flexural elements. Intermediate frames can include motion stops to prevent further relative motion during overload conditions. The device can also include a dampening structure, such as a spring or gas structure that includes a trapezoidal piston and corresponding cylinder, to provide damping during non-powered states. The capacitive plate is made of insulating material.

Abstract: A method of attaching two wafers in a seismometer comprising the steps of forming a patterned wetting metal layer on a first wafer and forming a plurality of cavities mirroring the pattern of the wetting metal layer on the first wafer. The steps further include pouring a plurality of solder balls on the surface of an alignment wafer, pouring off excess solder balls, aligning the first wafer with the alignment wafer, and connecting the first wafer with the alignment wafer. The solder balls are immobilized on the wetting metal layer by performing a partial reflow onto the wetting metal layer and removing the alignment wafer. The first and second wafers are aligned so that each solder ball is immobilized between the first and second wafer. The wafers are then bonded together.

Abstract: An accelerometer or a seismometer using an in-plane suspension geometry having a suspension plate and at least one fixed capacitive plate. The suspension plate is formed from a single piece and includes an external frame, a pair of flexural elements, and an integrated proof mass between the flexures. The flexural elements allow the proof mass to move in the sensitive direction in the plane of suspension while restricting movement in all off-axis directions. Off-axis motion of the proof mass is minimized by the use of intermediate frames disbursed within and between the flexural elements. Intermediate frames can include motion stops to prevent further relative motion during overload conditions. The device can also include a dampening structure, such as a spring or gas structure that includes a trapezoidal piston and corresponding cylinder, to provide damping during non-powered states. The capacitive plate is made of insulating material.

Abstract: The present invention is a seismometer/velocimeter, and can be also made to function as an accelerometer. The invention comprises an in-plane suspension geometry combined with a transverse periodic-sensing-array position transducer. The invention can incorporate a feedback actuator of magnetic design, incorporating fixed magnets and planar coils on the surface of the proof mass allowing for much lower noise than an equivalent electrostatic actuator without requiring high voltages. The invention may also have a dual-axis configuration by using two sets of springs. The nested suspensions allow the proof mass to move in two orthogonal directions. A three-axis configuration is possible by combining the dual-axis version with sensing and actuation of the proof mass motion out of the plane. The position sensing for the out-of-plane motion can be made using schemes common in existing state-of-the-art sensors. Actuation for the sensors may be electrostatic or electromagnetic in each of the axis.

Abstract: A method and a seismic sensor using symmetrical spring geometry to overcome the temperature sensitivity problems associated with seismometers. The seismic sensor includes a base having a pivot point and a vertical axis. The sensor also includes a neutral axis and a carriage that is mounted to the base at the pivot point. The carriage includes a mass, a boom, a center of gravity, and a neutral position. The carriage is in the neutral position when the center of gravity of the carriage is along the neutral axis. Also included in the sensor is a spring, that is attached to the carriage. The spring suspends the carriage in the neutral position and supplies a force that impels the carriage into the neutral position. The spring being symmetrical about the neutral axis while the carriage is in the neutral position. The sensor further includes a first point and a second point for attaching the spring to the carriage and a detector. The detector is attached to the base and senses the displacement of the carriage.

Abstract: An accelerograph for recording strong earthquake motion in three mutually perpendicular directions is disclosed. An electromagnetic starter is provided for use particularly with the accelerograph to initiate recording and to continue recording for an adjustable period of time of from 6 to 15 seconds after the last shock. The starter may comprise a single magnetically activated element which is disposed to respond to the first and subsequent P-waves, or it may comprise three such elements, one vertically oriented to respond to movements in the Z-axis, and two horizontally oriented to respond to movements in the X and Y-axes. Such starters may also be employed to open or shut off switches for any type of equipment or apparatus which should or should not be operating during an earthquake or immediately thereafter.