1. An intervertebral implant for a human spine, comprising:
a cage element comprising a superior surface and an inferior surface, wherein the inferior surface of the cage element is configured to support a first vertebra of the human spine to inhibit movement of the first vertebra towards a second vertebra, and wherein the superior surface of the cage element comprises a first opening;
an insert comprising a support surface for the second vertebra, wherein the support surface, during use, supports at least a portion of the second vertebra above and away from the superior surface of the cage element and inhibits movement of the second vertebra towards the first vertebra, and wherein the insert, during use, is inserted at least partially into the cage element; and
an expansion member that, during use, is inserted in the cage element through an opening in a side of the cage element to expand the intervertebral implant by elevating the insert to move a portion of the insert through the first opening in the superior surface of the cage element so that at least a portion of the support surface of the insert is raised above and away from the superior surface of the cage to support at least a portion of the second vertebra above and away from the superior surface of the cage element.
2. The intervertebral implant of claim 1, wherein the intervertebral implant is configured such that the direction of movement of the expansion member is substantially perpendicular to the direction of movement of the insert.
3. The intervertebral implant of claim 1, wherein the expansion member is configured to be advanced between an interior surface of the cage element and the inferior surface of the insert.
4. The intervertebral implant of claim 1, wherein the support surface of the insert comprises osteoconductive mesh structure.
5. The intervertebral implant of claim 1, wherein an interior surface of the cage element comprises a raised portion configured to inhibit backout of the expansion member after expansion of the intervertebral implant.
6. The intervertebral implant of claim 1, wherein the expansion member comprises an angled portion configured to engage an angled portion of the insert to facilitate insertion of the expansion member in the cage element.
7. The intervertebral implant of claim 1, wherein the support surface of the insert comprises at least a majority of a surface of the intervertebral implant that is configured to support the second vertebra.
8. The intervertebral implant of claim 1, wherein the support surface comprises a substantially planar surface that supports at least a portion of the second vertebra above and away from the superior surface of the cage element and inhibits movement of the second vertebra towards the first vertebra during use.
9. The intervertebral implant of claim 1, wherein the support surface of the insert comprises a substantially planar surface of sufficient cross-sectional area to support the second vertebra above and away from the superior surface of the cage element during use.
10. The intervertebral implant of claim 1, wherein, during use, the support surface of the insert supports the second vertebra above and away from the superior surface of the cage element such that the second vertebra does not contact the superior surface of the cage element.
11. The intervertebral implant of claim 1, wherein the expansion member is at least partially removed from the cage element after being inserted in the cage element through an opening in a side of the cage element to expand the intervertebral implant.
12. An intervertebral implant for a human spine, comprising:
a cage element comprising a superior surface and an inferior surface, wherein the inferior surface of the cage element is configured to support a first vertebra of the human spine to inhibit movement of the first vertebra towards a second vertebra, and wherein the superior surface of the cage element comprises an opening;
an insert comprising an inferior surface and a support surface for the second vertebra, wherein the support surface, during use, supports the at least a portion of the second vertebra above and away from the superior surface of the cage element and inhibits movement of the second vertebra towards the first vertebra, wherein the insert, during use, is inserted at least partially into the cage element such that at least a portion of the inferior surface of the insert is below the superior surface of the cage element and at least a portion of the support surface of the insert is above the superior surface of the cage element to support at least a portion of the second vertebra above and away from the superior surface of the cage element; and
an expansion member that, during use, is inserted in the cage element through an opening in a side of the cage element to elevate at least a portion of the insert through the opening in the superior surface of the cage element so that the support surface of the insert is raised above and away from the superior surface of the cage to support at least a portion of the second vertebra above and away from the superior surface of the cage element.
13. The intervertebral implant of claim 12, wherein the intervertebral implant is configured such that the direction of movement of the expansion member is substantially perpendicular to the direction of movement of the insert.
14. The intervertebral implant of claim 12, wherein the expansion member is configured to be advanced between an interior surface of the cage element and the inferior surface of the insert.
15. The intervertebral implant of claim 12, wherein the support surface of the insert comprises osteoconductive mesh structure.
16. The intervertebral implant of claim 12, wherein an interior surface of the cage element comprises a raised portion configured to inhibit backout of the expansion member after insertion of the expansion member.
17. The intervertebral implant of claim 12, wherein the expansion member comprises an angled portion configured to engage an angled portion of the insert to facilitate insertion of the expansion member in the cage element.
18. The intervertebral implant of claim 12, wherein the support surface of the insert comprises at least a majority of a surface of the intervertebral implant that is configured to support the second vertebra.
19. The intervertebral implant of claim 12, wherein the support surface comprises a substantially planar surface that supports at least a portion of the second vertebra above and away from the superior surface of the cage element and inhibits movement of the second vertebra towards the first vertebra during use.
20. The intervertebral implant of claim 12, wherein the support surface of the insert comprises a substantially planar surface of sufficient cross-sectional area to support the second vertebra above and away from the superior surface of the cage element during use.
21. The intervertebral implant of claim 12, wherein, during use, the support surface of the insert supports the second vertebra above and away from the superior surface of the cage element such that the second vertebra does not contact the superior surface of the cage element.
22. The intervertebral implant of claim 12, wherein the expansion member is at least partially removed from the cage element after being inserted in the cage element through the opening in a side of the cage element to elevate at least a portion of the insert.
23. An intervertebral implant for a human spine, comprising:
a cage element with a superior surface and an inferior surface, wherein the inferior surface of the cage element comprises a first opening and the superior surface of the cage element comprises a second opening;
a first insert, wherein, during use, at least a portion of the first insert is inserted at least partially into the first opening, and wherein the first insert comprises a support surface that, during use, supports at least a portion of a first vertebra below and away from the inferior surface of the cage element and inhibits movement of the first vertebra towards a second vertebra;
a second insert, wherein, during use, at least a portion of the second insert is inserted at least partially into the second opening, and wherein the second insert comprises a support surface that, during use, supports at least a portion of a second vertebra above and away from the superior surface of the cage element and inhibits movement of the second vertebra towards the first vertebra; and
an expansion member that, during use, is inserted in a third opening in the cage element to lower the support surface of the first insert below and away from the inferior surface of the cage element to support at least a portion of the first vertebra below and away from the inferior surface of the cage element and inhibit movement of the first vertebra towards a second vertebra,
wherein the expansion member when inserted in the third opening raises the support surface of the second insert above and away from the superior surface of the cage element to support at least a portion of the second vertebra above and away from the superior surface of the cage element and inhibit movement of the second vertebra towards the first vertebra.
24. The intervertebral implant of claim 23, wherein the intervertebral implant is configured such that the direction of movement of the expansion member is substantially perpendicular to the direction of movement of the first insert and the second insert.
25. The intervertebral implant of claim 23, wherein the expansion member is configured to be advanced between a superior surface of the first insert and an inferior surface of the second insert.
26. The intervertebral implant of claim 23, wherein the support surface of the first insert comprises osteoconductive mesh structure.
27. The intervertebral implant of claim 23, wherein the support surface of the second insert comprises osteoconductive mesh structure.
28. The intervertebral implant of claim 23, wherein an interior surface of the cage element comprises a raised portion configured to inhibit backout of the expansion member after insertion of the expansion member.
29. The intervertebral implant of claim 23, wherein expanding the intervertebral implant comprises increasing a height of the intervertebral implant.
30. The intervertebral implant of claim 23, wherein the expansion member comprises at least one angled portion configured to engage an angled portion of the first or second insert to facilitate insertion of the expansion member in the cage element.
31. The intervertebral implant of claim 23, wherein the support surface of the first insert comprises at least a majority of a surface of the intervertebral implant that is configured to support the first vertebra.
32. The intervertebral implant of claim 23, wherein the support surface of the second insert comprises at least a majority of a surface of the intervertebral implant that is configured to support the second vertebra.
33. The intervertebral implant of claim 23, wherein the support surface of the first insert comprises a substantially planar surface that supports at least a portion of the first vertebra above and away from the inferior surface of the cage element and inhibits movement of the second vertebra towards the first vertebra during use, and wherein the support surface of the second insert comprises a substantially planar surface that supports at least a portion of the second vertebra above and away from the superior surface of the cage element and inhibits movement of the second vertebra towards the first vertebra during use.
34. The intervertebral implant of claim 23, wherein the support surface of the first insert comprises a substantially planar surface of sufficient cross-sectional area to support the second vertebra below and away from the inferior surface of the cage element during use, and wherein the support surface of the second insert comprises a substantially planar surface of sufficient cross-sectional area to support the second vertebra above and away from the superior surface of the cage element during use.
35. The intervertebral implant of claim 23, wherein, during use, the support surface of the first insert supports at least a portion of a first vertebra below and away from the inferior surface of the cage element such that the first vertebra does not contact the inferior surface of the cage element, and the support surface of the second insert supports at least a portion of a second vertebra above and away from the superior surface of the cage element such that the second vertebra does not contact the superior surface of the cage element.
36. The intervertebral implant of claim 23, wherein the expansion member is at least partially removed from the cage element after being inserted in the third opening in the cage element to lower the support surface of the first insert below and away from the inferior surface of the cage element to support at least a portion of the first vertebra below and away from the inferior surface of the cage element and inhibit movement of the first vertebra towards a second vertebra.
37. An intervertebral implant for a human spine, comprising:
a first member comprising a first inferior surface and a first superior surface, where the first superior surface comprises a substantially planar surface configured to contact and support a first vertebra of a human spine;
a second member comprising a second inferior surface and a second superior surface, where the second inferior surface comprises a substantially planar surface configured to contact and support a second vertebra of a human spine;
a cage comprising a first opening in a superior surface of the cage and a second opening in an inferior surface of the cage, wherein, during use, the first member is inserted at least partially into the first opening and the second member is inserted at least partially in the second opening; and
an expansion element that, during use, is inserted between the first inferior surface of the first member and the second superior surface of the second member, wherein insertion of the expansion member expands the first and second members relative to one another to increase a separation distance between the first superior surface of the first member and the second inferior surface of the second member, wherein the first superior surface is expanded above the superior surface of the cage and the second inferior surface is expanded below the inferior surface of the cage, such that the distance between the first superior surface and the second inferior surface is greater than the distance between the superior surface and the inferior surface of the cage, and wherein the first superior surface supports at least a portion of the first vertebra above the superior surface of the cage and the second inferior surface supports at least a portion of the second vertebra below the inferior surface of the cage.
38. The intervertebral implant of claim 37, wherein the expansion element is at least partially removed from the cage element after being inserted between the first inferior surface of the first member and the second superior surface of the second member.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
What is claimed is:
1. A circuit for providing a back EMF signal that represents a back EMF voltage induced in a coil of a brushless motor, the circuit comprising:
an input node operable to receive a tap voltage from the coil; and
a network coupled to the input node and operable to generate the back EMF signal by removing a predetermined offset voltage from the tap voltage.
2. The circuit of claim 1, wherein the network includes:
an output node operable to carry the back EMF signal;
a control node operable to receive a control voltage Vcon;
an intermediate node;
a first resistor R1 coupled between the intermediate node and the input node;
a second resistor R2 coupled between the intermediate node and the control node; and
a third resistor R3 coupled between the intermediate node and the output node.
3. The circuit of claim 2, wherein Vcon(R1(R1R2))(offset voltage)2.
4. The circuit of claim 1, wherein the offset voltage includes a voltage drop induced by a driver of the motor.
5. The circuit of claim 4, wherein the voltage drop is across a diode of the driver.
6. The circuit of claim 1, wherein the back EMF signal has a zero crossing that substantially coincides with a zero crossing of the back EMF voltage.
7. The circuit of claim 1, wherein the offset voltage is generated by a current that flows through another coil of the motor.
8. A driver circuit for a sensorless brushless motor having a plurality of coils each inducing a respective back EMF voltage, the driver comprising:
a plurality of input nodes each operable to receive a tap voltage from a respective coil;
a plurality of networks each coupled to a respective input node and operable to generate a respective back EMF signal by removing a predetermined offset voltage from the corresponding tap voltage; and
a zero-crossing detector operable to receive the back EMF signals and determine there from when zero crossings of the respective back EMF voltages occur.
9. The driver of claim 8, wherein the motor is operable in a pulse width modulation (PWM) mode having a PWM-on state and a PWM-off state.
10. The driver of claim 8, wherein each network is further operable to generate the respective back EMF signal during a PWM-off state when the respective coil is floating.
11. A sensorless brushless motor assembly, comprising:
a sensorless brushless motor having a plurality of coils each generating a back EMF voltage during a respective floating period; and
a motor driver circuit including
a plurality of input nodes each operable to receive a tap voltage from a respective one of the coils;
a plurality of networks each coupled to a respective one of the input nodes and operable to generate a respective back EMF signal by removing a predetermined offset voltage from the corresponding tap voltage; and
a zero-crossing detector operable to receive the back EMF signals and to determine when the zero crossings of the back EMF voltages occur.
12. The motor assembly of claim 11, wherein the driver circuit further includes a controller operable to commutate the motor in response to the detected zero crossing.
13. The motor assembly of claim 11, wherein the motor is operable in a pulse width modulation (PWM) mode having a PWM-on state and a PWM-off state.
14. The motor assembly of claim 13, wherein each network is further operable to generate the back EMF signal during respective PWM-off states.
15. The motor assembly of claim 11, wherein each coil has one end coupled to a center tap and the tap voltage is provided proximate to another end of the coil.
16. A method of providing a back EMF signal that represents a back EMF voltage induced in a coil of a brushless motor, comprising:
receiving a tap voltage from the coil; and
generating the back EMF signal equal to the tap voltage minus a predetermined offset voltage.
17. A method of advancing a sensorless brushless motor having a plurality of coils, comprising:
receiving a tap voltage from one of the coils while the coil is floating;
removing a predetermined offset voltage from the tap voltage to generate a back EMF signal that represents a back EMF voltage induced in the floating coil;
detecting a zero crossing of the back EMF voltage from the back EMF signal; and
advancing the motor a step in a commutation sequence in response to detection of the zero crossing.
18. The method of claim 17, further comprising repeating the steps for a tap voltage from another coil.
19. A circuit for providing a back EMF signal that represents a back EMF voltage induced in a coil of a brushless motor, the circuit comprising:
means for receiving a tap voltage from the coil; and
means for generating the back EMF signal by removing a predetermined offset voltage from the tap voltage.