Abstract: A sensor unit for an electronic device having a pivotable cover member includes a signal emitter, a signal receiver spaced from the signal emitter, and a baffle attached to the cover member and disposed in the space between the signal emitter and the signal receiver when the cover is in its closed position. A transmit window disposed between the signal emitter and the signal receiver is permeable to signals falling within a specified wavelength range, thereby ensuring the accuracy of the signal. When the sensor unit is applied to a cellular phone, for example, the phone can be automatically in an "off hook" or "on hook" condition automatically in accordance with whether the cover member is in its open position or closed position, and an operator need only perform a single operation to answer or terminate a call or to power up the phone.

Abstract: An electro-optical scanning device reads indicia having parts of different light reflectivity, including bar codes and matrix arrays such as UPSCODES. The scanning device includes laser or light emitting diodes for emitting at least two light beams of the same or different wavelengths. The light beams may be visible to the human eye, and the beams are optically directed to form one or two scan lines to scan portions of a symbol. Dual photosensor(s) or a charge coupled device detects light reflected from the different portions of the symbol. The charge coupled device can be used to detect either reflected ambient light or the reflected visible light from the beams emitted by the diodes. The photosensors generate signals corresponding to the detected light which can be processed simultaneously. The device is particularly useful in reading two dimensional or more complex symbols. Methods for reading indicia are also described.

Abstract: In a ring laser gyroscope a laser beam is directed to travel in a closed path, however, temperature variations can cause a change in the path length which, if not corrected, can result in drift and scale factor errors. The present invention controls the length of this closed path or cavity by applying a force to the gyro normal to the lasing plane. This is accomplished by inserting a bolt through the longitude axis of the gyro and by utilizing the bolt to apply or to relieve force therefore maintaining the cavity length constant over a given temperature range.

Abstract: A cavity length control assembly for a ring laser gyro includes a mirror support to which a piezoelectric plate is mounted. The piezoelectric plate is mounted at a center post of the mirror support with a preload tension. An outer perimeter of the piezoelectric plate is supported against the perimeter of the mirror support, thereby permitting the piezoelectric plate to exert axial force against the perimeter, without being radially restrained at the perimeter.