Surveying instrument with image display unit

Claim 1

A surveying instrument comprising: a rotatably mounted optical system including an objective lens and a focusing lens; a solid-state image pickup element positioned to receive a light output from said optical system; a video signal processing circuit for processing video signals provided by said solid-state image pickup element, said video signal processing circuit comprising: a preamplifier receiving an output of said solid-state image pickup element, a low-pass filter receiving as an input an output of said preamplifier, a polarity coincidence circuit receiving as an input an output of said low-pass filter, a gamma correction circuit receiving as an input an output of said polarity coincidence circuit, a blanking insertion circuit receiving as an input an output of said gamma correction circuit, a luminance correcting circuit receiving as an input an output of said blanking insertion circuit, a video demodulator circuit receiving as an input an output of said luminance correcting circuit, a polarity switching circuit receiving as an input an output of said demodulator circuit, X and Y shift registers driving said image display section, said X shift register receiving as an input an output of said polarity switching circuit, a synchronizing signal separating circuit receiving as an input an output of said luminance correcting circuit, and a timing pulse generator circuit receiving as an input an output of said synchronizing signal separator circuit, outputs of said timing pulse generator circuit being applied to drive said X shift register and said Y shift register; and an image display section for displaying an image in response to outputs of said video signal processing circuit, said image display section being stationarily mounted on a body portion of said instrument.