GB1387854A - Electronic apparatus for measuring reflex actions - Google Patents

Abstract

1387854 Electro-physical measurement-reflexaction C J BIRTLES 20 July 1973 [4 May 1972] 20830/72 Heading G1N [Also in Division H3] The invention relates to the automatic measurement of animal reflexes, particularly human Achilles reflexes for thyroid diagnosis, using a photo-electric detector responsive to light reflected from the ball of the foot. The measurement is made as the time for the reflex response signal to reach a fraction e.g. half of its peak value. The time may be expressed as a clock pulse count, Fig.3, or a ramp signal from an integrator, Fig.4. A typical response curve is illustrated in Fig.1 with the point 1 indicating the hammer stimulus, and 6 the half peak height (arrived at in time t). FIG.3 OPERATION: The reflex signal is applied through a buffer amplifier T 1 , T, and to a pre-amplifier 12, and thence to a threshold (Schmidt trigger) 13 to actuate bi-stable 16 opening AND-gate 17 to pass clock pulses from 18 to counter 19 and printer 20. The output of the preamplifier is also applied via diodes D1, D2, to a memory/divided by two circuit 14 including capacitor C2 and resistors R7, R8 to provide a reference input to comparator 15 which switches bi-stable 16 to close the gate when the direct signal via D3 falls below the half-peak reference. FIG.4 OPERATION: The input is applied to terminals R, Y of amplifier OA1 feeding a halfpeak memory OA2 and comparator OA3, to reset at half-peak a bi-stable TR 2 , TR 3 which is initially triggered by the hammer switch. When triggered this bi-stable applies a reference voltage to an integrator TR 4 , OA5. The ramp output indicated by M, is also applied to a "threshold" comparator OA4 controlling a clamp transistor TR 1 to supress the hammer-stimulus-pulse, at the half-peak memory. (For Figures see next page)