Abstract: An acceleration sensor having a support frame, a weight supported within the support frame via flexible beams, semiconductor piezoresistance elements provided on the beams, and wiring interconnecting the piezoresistance elements. The acceleration sensor detects acceleration from changes in resistance of the piezoresistance elements. Stress damping sections are provided on those portions of the beams which exclude the portions where the piezoresistance elements are provided. Each stress damping section is symmetrical with respect to the point of intersection between the length center line of the beam and the width center line of the beam.

Abstract: A covered acceleration sensor element includes a support frame portion surrounding a weight portion, a plurality of flexible beam portions for connecting the weight portion to the support frame portion, and piezoresistance elements provided on the beam portions. An upper cover and a lower cover enclosing the periphery of the weight portion together with the support frame portion are joined to the face and back of the support frame portion. The support frame portion is separated by separation grooves into an inner frame and an outer frame. The plurality of inner frame support portions has flexibility. The beam portions are connected to both sides of the weight portion along the second axis and the third axis. The inner frame support portions are connected to both sides of the inner frame in a direction in which they are rotated nearly 45 degrees from the second axis and the third axis.

Abstract: A covered acceleration sensor element includes a weight portion, a support frame portion surrounding the weight portion, a plurality of flexible beam portions for connecting the weight portion to the support frame portion to support the weight portion, piezoresistance elements provided on the beam portions, and wirings for connecting them. An upper cover and a lower cover enclosing the periphery of the weight portion together with the support frame portion are joined to the face and back of the support frame portion. Acceleration in the directions of three axes, i.e., a first axis in the joining thickness direction, a second axis in a plane perpendicular to the first axis, and a third axis in the plane and perpendicular to the second axis, or acceleration in the direction of any of the axes, is detected from changes in the resistances of the piezoresistance elements. The support frame portion is separated by separation grooves into an inner frame and an outer frame.

Abstract: An acceleration sensor whose characteristics including sensitivity are less likely to change relative to disturbance force applied to a sensor chip. The acceleration sensor has a support frame, a weight supported within the support frame via flexible beams, semiconductor piezoresistance elements provided on the beams, and wiring interconnecting the piezoresistance elements. The acceleration sensor detects acceleration from changes in resistance of the piezoresistance elements. Stress damping sections are provided on those portions of the beams which exclude the portions where the piezoresistance elements are provided. Each stress damping section is symmetrical with respect to the point of intersection between the length center line of the beam and the width center line of the beam. When disturbance force is applied to a sensor element in the direction in which the entire each of the beams extends, the stress damping sections absorbs the disturbance force.

Abstract: Provided is a piezo-resistor type acceleration sensor in which an offset voltage does not fluctuate even when excessive impact/acceleration is applied. In the acceleration sensor, metal wires on top surfaces of a flexible portion and a weight are arranged in grooves formed on the flexible portion top surface/weight top surface. The acceleration sensor has a structure in which the metal wires do not hit an upper regulation plate even when the weight collides with the upper regulation plate, and the offset voltage fluctuation can be avoided.

Abstract: An acceleration sensor, which has realized such a high impact-resistance that a weight bottom surface of an acceleration sensor element does not directly collide with an inner bottom plate of a protection case made of ceramic, glass or silicon to avoid edges and corners of the weight bottom surface of the acceleration sensor element chipping, even when an excessive acceleration or impact is applied to the acceleration sensor. The acceleration sensor comprises the acceleration sensor element having in a center a weight that works as a pendulum when acceleration is applied, and the protection case housing the acceleration sensor element. The inner bottom plate of the protection case works as a regulation plate to prevent the weight from excessively swing downwards. An impact buffer material of a metal layer or a resin layer is provided on the weight bottom surface or the inner bottom plate of the protection case.

Abstract: A free fall detection device capable of detecting a fall accompanied by rotation is provided. A fall accompanied by rotation is detected based on a waveform of an acceleration signal output from the acceleration detection unit and an angular velocity signal output from the angular velocity detection unit. A gravity center acceleration of the device to be protected is calculated from the acceleration detected by the acceleration detection unit and from the angular velocity detected by the angular velocity detection unit. Even when the device being protected rotates as it falls, the fall of the device can be detected from the detected acceleration or angular velocity. Further, by calculating the gravity center acceleration not affected by the rotation, it is possible to detect a fall of the device with high precision even if the device rotates as it falls.

Abstract: Disclosed is a multi-range three-axis acceleration sensor device in which a plurality of three-axis acceleration sensor elements are formed without axial deviation among them in a single silicon chip and have different acceleration measurement ranges. Each of the plurality of sensor elements includes a weight, a frame surrounding the weight and flexible members composed of beams or diaphragm connecting the weight with the frame. Each of the plurality of sensor elements causes different output voltage for unit acceleration from another. A first three-axis acceleration sensor element among the plurality of sensor elements has other sensor elements of them formed in a frame of the first one and causes a larger output voltage for unit acceleration than the others.

Abstract: A semiconductor acceleration sensor is disclosed which has a small difference in acceleration detection sensitivity among X, Y, and Z axes and a high detection sensitivity. The acceleration sensor has a mass portion in its center, a support frame surrounding the mass portion, and a plurality of flexible arms connecting the mass portion and the support frame. The flexible arm has wider portions on both ends and a narrower portion between the wider portions. Piezo resistors are restrictedly provided within a top surface region of the wider portion of the flexible arm, and through holes connecting metal wires and the piezo resistors are disposed on the mass portion/support frame. The plurality of flexible arms are symmetric with respect to the center of the mass portion, and each of the flexible arms is symmetric with respect to the center line of the flexible arm.

Abstract: In a displacement detection device having an IC chip for a regulation plate, silicon broken pieces might drop from loose chippings during assembling or using the device and affect properties of the displacement detection device. By setting an angle of grinding traces on an IC chip wafer of chip with a vertical line on side ridges of the IC chip to less than 45 degrees, more preferably 10 to 45 degrees, the chippings including loose chippings can be reduced on the side ridges of the IC chip. Using of an IC chip having loose chippings on side ridges for a regulation plate can be avoided, and a highly reliable displacement detection device can be provided.

Abstract: An acceleration sensor, which has realized such a high impact-resistance that a weight bottom surface of an acceleration sensor element does not directly collide with an inner bottom plate of a protection case made of ceramic, glass or silicon to avoid edges and corners of the weight bottom surface of the acceleration sensor element chipping, even when an excessive acceleration or impact is applied to the acceleration sensor. The acceleration sensor comprises the acceleration sensor element having in a center a weight that works as a pendulum when acceleration is applied, and the protection case housing the acceleration sensor element. The inner bottom plate of the protection case works as a regulation plate to prevent the weight from excessively swing downwards. An impact buffer material of a metal layer or a resin layer is provided on the weight bottom surface or the inner bottom plate of the protection case.

Abstract: A free fall detection device capable of detecting a fall accompanied by rotation is provided. A fall accompanied by rotation is detected based on a waveform of an acceleration signal output from the acceleration detection unit and an angular velocity signal output from the angular velocity detection unit. A gravity center acceleration of the device to be protected is calculated from the acceleration detected by the acceleration detection unit and from the angular velocity detected by the angular velocity detection unit. Even when the device being protected rotates as it falls, the fall of the device can be detected from the detected acceleration or angular velocity. Further, by calculating the gravity center acceleration not affected by the rotation, it is possible to detect a fall of the device with high precision even if the device rotates as it falls.

Abstract: An acceleration sensor comprises an acceleration sensor element having a mass portion in the center, a thick frame surrounding the mass portion and a plurality of elastic support arms bridging the mass portion and the thick frame, and an upper regulation plate covering the acceleration sensor element and fixed on the thick frame with adhesive. The mass portion has, on the mass portion upper surface, connection portions connecting the mass portion with each of the arms, wired areas having lead wires on it and non-wired areas. The non-wired areas have a major area of the upper surface of the mass portion and are lower than the wired areas. The upper regulation plate has a first gap with the wired areas and a second gap with the non-wired areas, of which length is more than the sum of the first gap length, a lead wire thickness and 0.1 ?m (preferably 1.0 ?m).

Abstract: A semiconductor acceleration sensor is disclosed which has a small difference in acceleration detection sensitivity among X, Y, and Z axes and a high detection sensitivity. The acceleration sensor has a mass portion in its center, a support frame surrounding the mass portion, and a plurality of flexible arms connecting the mass portion and the support frame. The flexible arm has wider portions on both ends and a narrower portion between the wider portions. Piezo resistors are restrictedly provided within a top surface region of the wider portion of the flexible arm, and through holes connecting metal wires and the piezo resistors are disposed on the mass portion/support frame. The plurality of flexible arms are symmetric with respect to the center of the mass portion, and each of the flexible arms is symmetric with respect to the center line of the flexible arm.

Abstract: An acceleration sensor in which a regulation plate is fixed with adhesive onto a support frame of a sensor chip of the sensor to limit the movement of a mass portion of the sensor chip within a predetermined gap range. In the acceleration sensor, the adhesion area of the adhesive can be controlled to a predetermined value to prevent a variation of the sensitivity due to the variation of the adhesion area. The sensor chip comprises the mass portion, the frame surrounding the mass portion and having on an upper surface of the frame a plurality of the recesses to fill adhesive into, elastic support arms bridging the mass portion and the frame, and strain gauges formed on the elastic support arms. The regulation plate is fixed with paste onto the frame with the predetermined gap with an upper surface of the mass portion. The paste contains hard plastic balls, of a diameter larger than the predetermined gap, mixed with adhesive. The adhesive is preferably of silicon-rubber resin.

Abstract: An acceleration sensor is disclosed that has a structure in which elastic support arms are not broken even if subjected to an impact that may be caused during a usual handling. The acceleration sensor comprises a mass portion, a mass portion top plate fixed onto the mass portion, a rectangular thick support frame surrounding the mass portion, a frame top plate fixed onto the frame, and four elastic support arms hanging the mass portion in the center of the frame and bridging the mass portion top plate and the frame top plate. There are provided lateral grooves just below the support arms on side surfaces of the mass portion and on inner side surfaces of the frame. Due to the grooves, the mass portion top plate and the frame top plate have their portions bonded to the mass portion/the frame and their portions protruding toward the support arms. Cross sections on boundaries between the bonded portions and the protruding portions are larger than those connecting the protruding portions to the support arms.

Abstract: An acceleration sensor comprises an acceleration sensor element having a mass portion in the center, a thick frame surrounding the mass portion and a plurality of elastic support arms bridging the mass portion and the thick frame, and an upper regulation plate covering the acceleration sensor element and fixed on the thick frame with adhesive. The mass portion has, on the mass portion upper surface, connection portions connecting the mass portion with each of the arms, wired areas having lead wires on it and non-wired areas. The non-wired areas have a major area of the upper surface of the mass portion and are lower than the wired areas. The upper regulation plate has a first gap with the wired areas and a second gap with the non-wired areas, of which length is more than the sum of the first gap length, a lead wire thickness and 0.1 ?m (preferably 1.0 ?m).

Abstract: An ultra-small and slim semiconductor acceleration sensor with high sensitivity is provided. The acceleration sensor has a mass portion formed at a center part of a silicon semiconductor substrate, a frame formed on an edge part of the substrate, thin elastic support arms which are provided on top surfaces of the mass portion and the frame and connect the mass portion and the frame, and strain gauges constituted by a plurality of pairs of piezoresistors formed on top surfaces of the elastic support arms. A distance between a pair of Z-axis strain gauges provided on the top surface of the elastic support arm is made longer by 0.4L to 1.2L or shorter by 1.0L to 1.8L than a distance between a pair of X-axis strain gauges, whereby output of the Z-axis strain gauge is made at the same level as output of the X-axis strain gauge.

Abstract: An acceleration sensor in which a regulation plate is fixed with adhesive onto a support frame of a sensor chip of the sensor to limit the movement of a mass portion of the sensor chip within a predetermined gap range. In the acceleration sensor, the adhesion area of the adhesive can be controlled to a predetermined value to prevent a variation of the sensitivity due to the variation of the adhesion area. The sensor chip comprises the mass portion, the frame surrounding the mass portion and having on an upper surface of the frame a plurality of the recesses to fill adhesive into, elastic support arms bridging the mass portion and the frame, and strain gauges formed on the elastic support arms. The regulation plate is fixed with paste onto the frame with the predetermined gap with an upper surface of the mass portion. The paste contains hard plastic balls, of a diameter larger than the predetermined gap, mixed with adhesive. The adhesive is preferably of silicon-rubber resin.

Abstract: An acceleration sensor is disclosed that has a structure in which elastic support arms are not broken even if subjected to an impact that may be caused during a usual handling. The acceleration sensor comprises a mass portion, a mass portion top plate fixed onto the mass portion, a rectangular thick support frame surrounding the mass portion, a frame top plate fixed onto the frame, and four elastic support arms hanging the mass portion in the center of the frame and bridging the mass portion top plate and the frame top plate. There are provided lateral grooves just below the support arms on side surfaces of the mass portion and on inner side surfaces of the frame. Due to the grooves, the mass portion top plate and the frame top plate have their portions bonded to the mass portion/the frame and their portions protruding toward the support arms. Cross sections on boundaries between the bonded portions and the protruding portions are larger than those connecting the protruding portions to the support arms.