Thermographic infra-red medical diagnostic camera - has picture point signals subtracted from preferred picture point signal for automation and error reduction

摘要

The thermographic infra-red medical diagnostic camera has a subtraction circuit (5) to form the difference between the picture point signals from its infrared sensor (4) and the picture point signal from a preferred picture point. The signal from the preferred picture point is periodically gated (6) into a memory (10) coupled to the subtraction circuit. The gate is controlled by an AND-gate (9) coupled to the camera deflection stage (3) via two variable delay circuits (7, 8). The advantage lies in almost total automation, and in errors due to infra-red sensor drift having practically no effect on processing. The camera resolution is also increased.