Radiant energy – Photocells; circuits and apparatus – Photocell controlled circuit
Patent
1984-08-06
1986-11-11
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Photocell controlled circuit
330284, H01J 4014
Patent
active
046224599
ABSTRACT:
An optical sensor system (10) in the form of a hand held tonometer probe has an infrared emitting diode (34) and a phototransistor detector (36) positioned to receive light from the diode (34). A rod (18) serves as a variable attenuator to intercept a portion of light from the diode (34) directed at the detector (36). A signal level detecting amplifier (104) is coupled to the detector (36) to receive an output signal from the detector (36) in response to light from the diode (34) received by the detector (36). The amplifier (104) has a non-inverting input (102) and an inverting input (106). The amplifier (104) receives the output signal from detector (36) at non-inverting input (102). A +5 volt reference potential is connected through a variable resistor (110) and a resistor (108) to establish a bias at the inverting input (106) which is approximately equal to signal levels supplied by the detector (36) to the non-inverting input (102). Rod (18) is movably mounted in housing portion (28) by a spring assembly (24) bonded to housing portion (28) by epoxy (26). Spring assembly (24) has planar rings (40, 42 and 44) encircling the rod (18). Planar springs (52, 54 and 56) extend from the rings (40, 42 and 44) and have their distal ends fixedly attached to the rod (18). The low noise amplifier and interface circuit (72) provides an output proportional to the displacment of rod (18) during pressure measurements.
REFERENCES:
patent: 3992926 (1976-11-01), Berryhill
Tassell, Electronic Engineering, vol. 52, No. 637, p. 23, Mid-Apr. 1980.
Penfold, Radio and Electronics Constructor, vol. 33, No. 10, pp. 604-608, (particularly FIG. 1).
Bouge Harry A.
Haley Tim O.
Gatto James G.
Gregg Edward B.
Higgins Willis E.
Nelms David C.
Professional Technologies Corp.
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