United Technologies Corporation

Ambac Industries, Inc.

Otis Elevator Company

Breed Technologies, Inc.

Walter J Wiegand, Jr

Robert H Bullis

James L Swindal

Frank W Gobetz

Charles B Brahm

Harold D Meyer

John A Kimberley

James R Voss

William L Nighan

Christopher A Parent

Robert A DiDomenico

Paul L Provenzano

Thomas M McHugh

Robert J Kuhlberg

Daniel H Grantham

Carl M Ferrar

Robert J Mongeon

Richard E Swarts

Russell G Meyerand, Jr

Mario T Lopiccolo

Arthur G Foyt

James W Lennon

James P Towey

A silicon capacitive microsensor which is sensitive to acceleration forces includes a silicon capacitive sensing element 10 comprising three silicon layers 12,16,26 having glass dielectric layers 14,24 between each pair of silicon layers with the middle silicon layer 16 consisting of a proof mass 18 suspended between the two glass dielectric layers 14,24 by a silicon hinge 20 which is connected to a slightly thicker silicon support layer 17 around the periphery (FIG. 3 ) between the glass layers 14,24 (FIG. 1 ). Three metallic bond pads 40,42,44 on the surface 45 of the silicon layers 26,16,12, respectively, are soldered to circuit trace pads 108 on a circuit board 100 which has a glass upper layer 104 and a silicon support layer 102. The thermal expansion coefficient between the glass layer 104 and the sensing element 10 are substantially the same, thereby minimizing thermally induced stresses on the sensing element 10 and minimizing inaccuracies associated therewith. Such direct mounting greatly simplifies the manufacturing process for such sensors. Also, such direct mounting eliminates flying leads thereby allowing the sensing element 10 to be fabricated to much smaller dimensions than that of the prior art.

Sensor having direct-mounted sensing element

A silicon capacitive pressure sensor is disclosed that has a glass dielectric material sputter-deposited onto a silicon substrate of the sensor. After deposition of the bulk dielectric material, the glass is patterned and etched to form a pair of concentric rings. An inner ring is of a circular shape, while the outer ring is of an octagonal shape. As compared to prior art dielectric spacers which are of a single ring of relatively wide thickness, the pair of concentric rings disclosed herein significantly reduce the parasitic capacitance of the glass dielectric material, thereby increasing the sensitivity of the sensor.

Capacitive pressure sensor having a reduced area dielectric spacer

A dual-element, parallel-plate silicon capacitative pressure sensor includes a pressure sensing element and a reference element of identical structure. Both elements are separately fabricated from the same silicon wafers using identical processing steps. Further, both elements are simultaneously mounted to a header using identical mounting steps. Such identical fabrication and mounting steps serve to identically match the dielectric materials and, thus, the aging properties of both the sensing and reference elements. By matching the sensing and reference elements in these ways, and by aging these components at elevated temperatures in exactly the same way, it is possible to achieve an extremely close match in long-term dielectric aging properties.

Method of manufacturing silicon pressure sensor having dual elements

A dual-element, parallel-plate silicon capacitative pressure sensor includes a pressure sensing element and a reference element of identical structure. Both elements are fabricated from the same silicon wafers using identical processing steps. Further, both elements are simultaneously mounted to a header using identical mounting steps. Such identical fabrication and mounting steps serve to identically match the dielectric materials and, thus, the aging properties of both the sensing and reference elements. By matching the sensing and reference elements in these ways, and by aging these components at elevated temperatures in exactly the same way, it is possible to achieve an extremely close match in long-term dielectric aging properties.

Reference element for high accuracy silicon capacitive pressure sensor

An obstruction detection system includes emitters, a sensor, and obstruction detection circuitry. The emitters mounted along the top of an opening radiate a plane of light toward the floor. The plane of light intersects the floor and creates a floorline at the intersection of the plane of light and the floor. The plane of light also intersects the door edge and creates a door edge line at the intersection of the door edge and the plane of light. A sensor, located outside the plane of light, monitors the opening so that the presence of the obstruction can be detected from a change in a received light pattern of the floorline, the door edge line, and from reflections from an obstruction in the plane of light. The sensor provides an output signal in response to the received light pattern to a means for analyzing said sensor output signal for obstruction detection.

Optical obstruction detector with light barriers having planes of light

A silicon capacitive pressure sensor is disclosed having a silicon substrate and a silicon diaphragm separated by a glass dielectric spacer. The substrate has an upper surface formed as a mesa which is generally curved in shape, the curvature being concave. Due to manufacturing constraints the mesa upper surface comprises a series of concentric rings that approximate the desired concave shape. The step height and diameter of the rings are such that, at full deflection of the diaphragm, the diaphragm touches the center of the mesa, but not the edges of the individual steps. That is, letting the edges or corners of the steps define a curve, the radius of curvature of the diaphragm is smaller than the radius of curvature of the locus of the step corners.

Capacitive pressure sensor having a substrate with a curved mesa

Pressure sensors utilizing capacitance variations to sense pressure variations of the silicon-on-silicon type in which dielectric drift, which occurs in such sensors due to the changing characteristics primarily of the dielectric wall support layer (16) extending up from the silicon substrate (12) between it and the silicon diaphragm (11), is minimized by in turn minimizing the contribution of the dielectric layer to the total capacitance of the sensor (10), reducing the dielectric contribution of the capacitance from, for example, about fifty (50%) percent down to a range of no more than about twenty to twenty-five (20-25%) percent and down typically to sixteen to about ten (16%-10%) percent of the total capacitance or lower. Three exemplary approaches are illustrated, namely, etching the outer edges of the dielectric layer, making the wall(s) it form(s) thinner (FIG. 2); reducing the horizontal thickness of the effective peripheral, lower edge(s) of the silicon diaphragm where it interfaces in contact with the wall(s) formed by the dielectric layer (FIG. 3); and/or reducing the horizontal thickness of the effective peripheral, upper edge(s) of the silicon base or substrate where it interfaces with the wall(s) formed by the dielectric layer (FIUG. 4); and/or a combination of one or more of these approaches or any other approach that minimizes the effective capacitive contribution of the peripheral dielectric layer to the total capacitance of the sensor and hence to long term drift.

Capacitive sensor with minimized dielectric drift

A micromachined three-plate capacitive accelerometer incorporates hinges attached to top and bottom surfaces of the proof mass that are symmetric about X and Y axes and also about diagonal axes; passageways for gas film damping in the fixed members that do not affect the capacitance to any significant degree; and provision for independently selecting two of the parameters sensitivity, capacitance and maximum acceleration.

Capacitive accelerometer with separable damping and sensitivity

Closed-loop capacitive accelerometer with spring constraint

Capacitive accelerometer with hinges on top and bottom surface

The present invention is related to a sight glass(10) that utilizes both reflected light at a glass to air interface(40) as well as the light transmitted through a glass to fluid to glass interface(44) to form a light pattern that is indicative of the true fluid level. By requiring that light always appear in either an 'air' or 'fluid' channel(42,46), any absence of light is assumed due to film coated surfaces or to other abnormal conditions. An absence of light is a signal that maintenance is required.

Optical fluid level sensor

The method and apparatus for generating start of combustion signals associated with the combustion events in a diesel engine (10), and for using such signals to control the timing of fuel delivery to the engine. The combustion event is sensed, as by an electrostatic (230, 330) or optical (130, 430) sensor, and signal conditioning circuitry (32) provides a start-of-combustion (SOC) signal (34) which is directly and precisely indicative of the time of the onset of combustion. The sensors (130, 230) include self-cleaning capabilities (48, 248) for extended operating life on an engine. The sensors may be incorporated in the structure of a glow plug (330, 430). The SOC signal (34) is advantageously supplied to a timing control circuit (26) which delivers a timing control signal (28) to a fuel delivery device, such as the controller (16') associated with a fuel pump (16). The control circuit (26) stores (65) one or more start of combustion values (SOC*) which indicate the desired timing, relative to an engine cycle (24), for the start of the combustion event as a function of speed (25) and load (27). One or more adjustment signals (.DELTA.SOC) are stored (75) and applied (67, 68) as a function of speed and load to adjust the desired signal (SOC*) such that the control signal (28, SOC.sub.c) is corrected for delays. The actual SOC signal (34) is compared (71) with the desired signal (66) to generate an error signal (72) which may be used to finely adjust the stored (75) .DELTA.SOC signal for particular speed and load conditions.

Method and apparatus for controlling fuel injection timing in a

A display device employs an electric discharge passing through a mixture of gases to form an excimer that fluoresces in the blue/green region of the optical spectrum.

Optical display with excimer fluorescence

The method and apparatus for generating start of combustion signals associated with the combustion events in a diesel engine, and for using such signals to control the timing of fuel delivery to the engine. The combustion event is sensed, as by an electrostatic or optical sensor, and signal conditioning circuitry provides a start-of-combustion signal which is directly and precisely indicative of the time of the onset of combustion. The sensors include self-cleaning capabilities for extended operating life on an engine. The sensors may be incorporated in the structure of a glow plug. The SOC signal is advantageously supplied to a timing control circuit which delivers a timing control signal to a fuel delivery device, such as the controller associated with a fuel pump. The control circuit stores one or more start of combustion values which indicate the desired timing, relative to an engine cycle, for the start of the combustion event as a function of speed and load. One or more adjustment signals are stored and applied as a function of speed and load to adjust the desired signal such that the control signal is corrected for delays. The actual SOC signal is compared with the desired signal to generate an error signal which may be used to finely adjust the stored .DELTA.SOC signal for particular speed and load conditions.

A flowmeter for the measurement of fluid flow employs a combination of two transit times for the passage of charged particles through a known distance under different conditions. Applications include the measurement of the air-fuel mixture in automobile engines.

Growing community of inventors

Glastonbury, CT, United States of America

Walter J Wiegand, Jr