Abstract: A thermoelectric heat exchanger includes a first finned heat sink which includes at least two planar regions, at least two second heat sinks, each shaped to fit a respective one of the planar regions. At least two sets of thermoelectric cooling elements are provided, each set made up of three cooling elements arranged in a triangular pattern in a respective one of the planar regions between the first heat sink and the corresponding second heat sink. The cooling elements are connected together in series within each set and an electric voltage is applied in parallel across each of the sets of cooling elements. The second heat sinks are secured to the first heat sink to create a low thermal resistance contact between the cooling elements and the heat sinks, with each of the cooling elements establishing at least point contact with both of the respective heat sinks.

Abstract: A machine control system includes a CRT on which a five bit screen image code is displayed, indicative of the particular screen image being displayed. Five sensors are mounted such that each senses a respective one of the code regions of the screen image code and generates a respective sensor signal. A controller compares the sensor signals with the screen image code for a commanded one of the screen images and indicates any disparity therebetween. In this way, a positive check is provided that the display screen actually displays the intended one of the image screens, and that the screen is in fact functional. In addition, a plurality of pushbuttons are provided which operate in two separate modes. In the first mode the pushbuttons provide programming inputs to the controller and in the second mode the pushbuttons act to control the machine directly via an alternate device, bypassing the controller.