1. A spinal fixation system for orthopedic rod implantation, comprising:
a bone screw having a threaded shank portion and a substantially spherical head portion;
a rod base member having a pair of spaced apart arms at least partially defining a pair of slots, said arms having a set of first inwardly facing interior first threaded surfaces forming a portion of a pass-through aperture extending along the length of said spaced apart arms and adapted to allow said threaded shank portion to pass between said spaced apart arms and having a seat adapted to retain said spherical head portion in the pass-through aperture, said rod base member also including a second threaded surface with threads different than threads on the first threaded surfaces;
a cap member positioned adjacent an end portion of said spherical head portion, said cap member providing a seating surface for an upper surface portion of said spherical head and a support base for a stabilizing rod placed within said slots; and
a set screw threadably engageable along said first threaded surfaces for engaging a stabilizing rod against said cap member wherein said cap member and set screw secure said rod base member in a fixed position by frictional engagement with said spherical head portion of said bone screw.
2. The spinal fixation system of claim 1 including a stabilizing rod positioned in the slots and between the set screw and cap member.
3. The spinal fixation system of claim 2 wherein said first threaded surfaces being are adapted to engage said set screw and sized to allow unobstructed insertion of said bone screw threaded shank through said pass-through aperture.
4. The spinal fixation system of claim 1 wherein said pass-through aperture includes a seat surface receptive to a surface portion of said spherical head portion.
5. The spinal fixation system of claim 2 wherein said slots being generally U-shaped and being on opposite sides of the rod base member with the arms therebetween.
6. The spinal fixation system of claim 1 wherein the threads on said set screw are configured to prevent splaying of said rod member base.
7. The spinal fixation system of claim 1 wherein said cap member having a sidewall that is generally cylindrical in shape and is provided with a generally flat surface on one end and generally semi spherical surface on an opposite end.
8. The spinal fixation system of claim 7 wherein the cap member further includes an aperture which extends between the generally flat surface on one end of the cap member and the generally semi spherical surface on the opposite end of the cap member.
9. The spinal fixation system of claim 1 wherein the cap member further includes resilient friction fingers on the cylindrical wall thereof which are in opposed relationship to one another.
10. The spinal fixation system of claim 1 wherein the cap member includes annular ridges on the generally cylindrical sidewall of the cap member at the top and bottom thereof.
11. The spinal fixation system of claim 10 wherein the base member includes an interference diameter within the pass-through aperture that cooperates with the top annular ridge to prevent the cap member from backing up.
12. The spinal fixation system of claim 1 wherein the cap member includes an aperture opening onto the seating surface.
13. The spinal fixation system of claim 1 wherein the head portion of the screw includes a tool socket.
14. The spinal fixation system of claim 2 wherein the set screw includes generally opposed first and second end walls, said first end wall being generally flat and in abutting relationship to said rod, said second end wall being generally flat and having a tool socket opening thereon for driving said set screw.
15. A spinal fixation system for orthopedic rod implantation, comprising:
a bone screw having first threads on a threaded shank portion and having a substantially spherical head portion, said threaded shank portion having a decreasing thread diameter adjacent a distal end of the threaded shank portion;
a rod base member having a sidewall with a pair of spaced apart arms at least partially defining a pair of slots opening into a pass-through aperture, said arms having a set of first inwardly facing first surfaces forming a portion of the pass-through aperture extending along the length of said spaced apart arms, said first surfaces having inwardly extending second threads with a finer pitch than the first threads and adapted to allow said threaded shank portion to pass between said spaced apart arms, said rod base member having a seat adapted to retain said spherical head portion in the pass-through aperture, said rod base member also including a second surface portion extending for the first surfaces along at least a portion of the length of the pass through aperture;
a cap member positioned in the pass-through aperture adjacent an end portion of said spherical head portion, said cap member providing a seating surface for an upper surface portion of said spherical head and a support base for a stabilizing rod placed within said slots; and
a set screw threadably engageable along said first threaded surfaces for engaging a stabilizing rod against said cap member wherein said cap member and set screw secure said rod base member in a fixed position by frictional engagement with said spherical head portion of said bone screw.
16. The spinal fixation system of claim 15 wherein the second surface portion being threaded with threads having a coarser pitch than the pitch of the second threads.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An acceleration sensor comprising:
a piezoelectric vibration device;
an oscillation circuit; and
a detection circuit,
wherein
the piezoelectric vibration device includes a substrate, an insulation layer formed above the substrate, a vibration section forming layer formed above the insulation layer, a vibration section formed in a cantilever shape in a first opening section that penetrates the vibration section forming layer, a second opening section that penetrates the insulation layer and formed below the first opening section and the vibration section, and a piezoelectric element section formed on the vibration section, the piezoelectric element section including a lower electrode, a piezoelectric layer formed on the lower electrode, and an upper electrode formed on the piezoelectric layer, the lower electrode having a larger area than an area of the piezoelectric layer, extending in a first direction toward the first opening section to a greater extent than the piezoelectric layer and the upper electrode, and extending in a second direction, opposite the first direction, to a greater extent than the piezoelectric layer and the upper electrode,
the oscillation circuit vibrates the piezoelectric vibration device at a resonance frequency, and
the detection circuit detects a change in the frequency of vibration of the piezoelectric vibration device which is caused by an acceleration applied in a direction in which the vibration section extends, and outputs a signal corresponding to the acceleration based on the change in the frequency.
2. An acceleration sensor according to claim 1, wherein the piezoelectric layer is may be formed from at least one of lead zirconate titanate, aluminum nitride, solid solution of lead zirconate titanate and solid solution of aluminum nitride.
3. An acceleration sensor according to claim 1, wherein the insulation layer is formed from silicon oxide, and the vibration section forming layer is formed from silicon.
4. An electronic device comprising the acceleration sensor recited in claim 1.