Abstract: A balancing chuck is disclosed for semiconductor wafers having a flat region which typically causes wafer imbalance on spinning equipment. The wafer's flat region is determined by a proximity sensor mounted on a centering arm overlying the wafer. The chuck is constructed to include an annular race containing a spherical counterweight. As the chuck is rotated to determine the wafer's flat region, a magnet prevents movement of the spherical counterweight within the race and allows for its subsequent alignment with the mass imbalance. A plurality of circumferential pockets are provided within the race to retain the position of the counterweight which functions as a counterbalance maintained in proper angular alignment during spinning of the chuck.

Abstract: A wristwatch has a plurality of light emitting digital readout elements which are located along one end of the watch above the watchband. A hermetically sealed time capsule is enclosed within the watch case and includes an integrated circuit chip which divides the frequency output of a battery powered quartz crystal oscillator into a series of pulses which are counted and selectively interrogated to provide a series of electrical outputs corresponding to seconds, minutes, hours, days, months and years. The time capsule includes sealed control switches which are actuated by magnets slidably mounted on the case and which provide for selecting different outputs for visual display on the readout elements, corresponding to either hours and minutes, month and day or seconds. The electronic circuitry automatically compensates for 28, 30 and 31 day months as well as for leap years, and the readout may be selected for repetitive 12 hours or 24 hour display.