TRANSDUCER DRIVER FOR MEASURING A PARAMETER OF THE MUSCULARSKELETAL SYSTEM

• US 20100331685A1
• Filed: 06/29/2010
• Published: 12/30/2010
• Est. Priority Date: 06/30/2009
• Status: Abandoned Application

• Current Assignee: OrthoSensor, Inc (Stryker Corporation)
• Original Assignee: OrthoSensor, Inc (Stryker Corporation)
• Inventors: Stein, Marc, Kelly, Andrew
• Application Number:
  US12/826,109
• Publication Number:
  US 20100331685A1
• Time in Patent Office: Days
• US Class Current: 600/438
• CPC Class Codes: A61B 5/4509 Bone density determination
• CPC Class Codes: A61B 5/4528 Joints A61B5/4533, A61B5/4538 take precedence
• CPC Class Codes: A61B 5/6846 specially adapted to be brought in contact with an internal body part, i.e. invasive
• CPC Class Codes: A61B 5/6878 Bone
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61B 8/15 Transmission-tomography

Abstract

A measurement system for capturing a transit time, phase, or frequency of energy waves propagating through a propagation medium is disclosed. The measurement system comprises two different closed-loop feedback paths. The first path includes a transducer driver (726), a transducer (704), a propagation structure (702), a transducer (706), and a zero-crossing receiver (740). The transducer driver (726) efficiently drives the transducer (704) and comprises a digital driver (106), a level shifter (112), and a matching network (114). A second path includes a transducer driver (1126), a transducer (1104), a propagation medium (1102), a reflecting surface (1106), and an edge-detect receiver (1140). Energy waves in the propagating medium (1102) are reflected at least once. The edge-detect receiver (1140) detects a wave front of an energy wave. Each positive closed-loop path maintains the emission, propagation, and detection of energy waves in the propagation medium.

Claims

1. A transducer driver circuit in a positive closed-loop path that generates time and frequency specific energy waves and pulses to measure a parameter of the muscular-skeletal system.

2. The driver circuit of claim 1 further comprising a level shifter to raise or lower voltage levels of output pulses to voltage levels required to efficiently drive an energy emitting resonator or transducer given the characteristics of the resonator or transducer.

3. The driver circuit of claim 2 further comprising an impedance matching network to translate a digital output pulse into a required wave shape for efficiently and compactly driving the transducer.

4. The driver circuit of claim 3 further comprising control logic to generate drive signals according to the transducer characteristics and operational modes to achieve highly accurate control, timing, and duration of the generated energy waves and pulses.

5. The driver circuit of claim 4 where the driver circuit drives more than one transducer.

6. The driver circuit of claim 4 where the impedance matching network comprises a pi network.

7. The driver circuit of claim 4 where the driver circuit controls a duration of stimulation of the transducer.

8. The driver circuit of claim 4 further including a sensor in the positive closed-loop comprising:

a first transducer;

a propagation medium where the first transducer is coupled to the propagation medium at a first location; and

a second transducer coupled to the propagation medium at a second location where the propagation medium is affected by the parameter of the muscular-skeletal system being measured and where there is a known relationship between the parameter being measured and one of transit time, phase, and frequency of energy waves propagating through the medium.

9. The driver circuit of claim 4 further including a sensor in the positive closed-loop comprising:

a transducer;

a propagation medium where the transducer is coupled to the propagation medium at a first location; and

a reflecting surface coupled to the propagation medium at a second location where the propagation medium is affected by the parameter of the muscular-skeletal system being measured and where there is a known relationship between the parameter being measured and one of transit time, phase, and frequency of energy waves propagating through the medium.

10. The driver circuit of claim 1 where the transducer driver circuit maintains positive closed loop feedback operating in at least one of continuous wave mode, pulse-loop mode, and pulse echo-mode.

11. A sensor comprising:

a first transducer;

a propagation medium where the first transducer is coupled to the propagation medium at a first location; and

a second transducer coupled to the propagation medium at a second location where the series and parallel resonance of the first transducer does not overlap the series and parallel resonance of the second transducer.

12. The sensor of claim 11 where the series and parallel resonance of the first transducer is less than the series and parallel resonance of the second transducer.

13. The sensor of claim 11 where the series and parallel resonance of the first transducer is greater than the series and parallel resonance of the second transducer.

14. The sensor of claim 11 where the propagation medium is a compressible waveguide to contain, propagate, and direct energy waves.

15. The sensor of claim 11 where the first transducer emits ultrasonic energy waves into the propagation medium at the first location.

16. A sensor system comprising:

a transducer driver coupled in positive closed-loop feedback comprising;

a digital driver having an input and an output;

a level shifter having an input coupled to the input of the digital driver and an output; and

a matching network having an input coupled to an output of the level shifter and an output.

17. The sensor system of claim 16 further including:

a sensor in the positive closed-loop feedback comprising;

a transducer having a terminal coupled to the output of the matching network; and

a compressible propagation medium where the transducer couples to the medium at a first location and where the transducer is enabled to emit ultrasonic energy waves into the propagation medium.

18. The sensor system of claim 17 further including a reflecting surface at a second location of the propagation medium.

19. The sensor system of claim 17 further including a second transducer coupled to a second location of the propagation medium where the second transducer includes a terminal coupled to the input of the digital driver.

20. The sensor system of claim 17 further including:

a control logic circuit having an input and an output coupled to the input of the digital driver; and

an amplifier having an input coupled to the output of the level shifter and an output coupled to the input of the matching network where the sensor system measures one of transit time, phase, and frequency of the ultrasonic energy waves propagating through the propagation medium.