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US 3,938,503 AGranted
Achilles reflex test system
AssigneeJ. M. Richards Laboratories
InventorVincent A. Vis
Life of this patent
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AssigneeJ. M. Richards Laboratories
InventorVincent A. Vis
Estimating the term…
A system for measuring the duration of the Achilles tendon reflex after the tendon has been tapped by a percussion hammer, the system including an input transducer which converts the reflex extension of the ankle joint to an electric signal which is fed to the input of an amplifier, the output of the amplifier being fed to a peak holder and to a comparator circuit. A portion of the signal from the peak holder is also fed to the comparator circuit which detects a crossover point of the two signals fed to the comparator. The first such crossover occurs during the hammer tap "artefact" and the second such crossover occurs during the relaxation phase of the reflex action. A timing device (such as an integrator) measures the time elapsed between the two crossovers and displays the result. The system also includes a reset switch which is interconnected with the peak holder, the flip flop, and the integrator circuits to reset those circuits and the system further includes an input offset compensator circuit, the output of the input offset compensator circuit being fed to the input circuit of the amplifier to provide sufficient current to reduce or increase the output of the amplifier to zero with zero input signal being fed to the input of the transducer.
A system for sensing the lapse of time between the peak contraction and the one-half relaxation point on a curve created by sensing the displacement of a foot in response to tapping the achilles tendon of the foot, the resulting curve having at least a first and second peak component having first and second peaks, the system comprising transducer means positioned to respond to the displacement of the foot and generating the curve, means connected to said transducer means for detecting a characteristic of the first peak of the curve and generating a first signal in response thereto and detecting the same characteristic of the second peak and generating a second signal in response thereto, said characteristic being relaxation points defined by a ratio of the characteristic point amplitude to the peak amplitude of said first and second peak components, bi-stable circuit means connected to said detector means having a first and second stable state, said bi-stable circuit means being in said first state in response to said first signal and being switched to said second state in response to said second signal, integrator circuit means including output means connected to said bi-stable circuit means and responsive to said first and second stable states, said integrator circuit means timing the period between said first and second characteristic and providing an output thereof, and reset circuit means connected to said detector means, bi-stable circuit means and said integrator circuit means for resetting said various means subsequent to the occurrence of said second characteristic.
Dependencies are inferred from the claim text.