Nippon Kogaku K.k.

Kenji Fujii

Hiroshi Ohki

Hidehiro Ogawa

Akio Takahama

A surveying instrument in which the azimuth angle setting device is incorporated has a collimating telescope which is rotatable around at least a vertical axis. The azimuth angle setting device comprises horizontal angle detection means for producing an electrical signal corresponding to at least a horizontal angle around which the collimating telescope rotates, input means for entering a coordinate, memory means for storing the horizontal angle signal produced by the horizontal angle detection means and the input coordinate entered by the input means, and processing means for calculating a direction of magnetic north based on the coordinate of a measurement point at which the surveying instrument is mounted, entered to the memory means by the input means and a coordinate of a target to be collimated by the collimating telescope. An azimuth angle relative to the magnetic north is determined by the processing means based on the horizontal angle of the horizontal angle detection means when the target is collimated and the magnetic north, and the azimuth angle is displayed on a display.

Surveying instrument

A conventional position detecting device for determining the position of a pattern having light and dark areas projected on a image sensor, in which the output signal from the image sensor is converted into a quantized signal through a sample and hold circuit. An improvement according to the invention is provided with a filter for cutting off the frequency components of the quantized signal above a clock frequency used for reading photoelectric outputs in the image sensor to convert the quantized signal into an analog signal to be used for determining the position of the pattern, whereby a high resolving power not limited by the length of each element of the image sensor is achieved.

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Chigasaki, Japan

Kenji Fujii