Radiant energy – Photocells; circuits and apparatus – Photocell controls its own optical systems
Reexamination Certificate
2008-04-22
2008-04-22
Epps, Georgia (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Photocell controls its own optical systems
C356S004030
Reexamination Certificate
active
07361874
ABSTRACT:
An auto focusing mechanism is provided in a surveying instrument, such as an electronic level, that is capable of automatically focusing a telescope on a sighted staff.As a focusing lens (21b) is moved by a motor (41) along the optical axis of a telescope (20), the image of a staff (1) sighted by the telescope (20) is converted into an electrical signal by a line sensor (24). The output signal of the line sensor (24) is converted into a digital signal by an A/D converter (27) and stored in a RAM (28). Based on the data stored in the RAM (28), a microcomputer (3) monitors frequencies of the component signals, or wavelets, contained in the output signal of the line sensor (24) stored in the RAM (28). When a particular frequency of the output signal associated with the position of the focusing lens (21b) is detected a determination is made that the focusing lens (21b) is located at a focusing position, and the distance from the telescope (20) to the staff (1) is calculated.
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patent: 5738104 (1998-04-01), Lo et al.
patent: 5742378 (1998-04-01), Kumagai et al.
patent: 6108920 (2000-08-01), Kinoshita
patent: 6960749 (2005-11-01), Nakamura
patent: 2006/0006308 (2006-01-01), Konishi
patent: 2001-12949 (2001-01-01), None
Nagao Takashi
Nishita Nobuyuki
Shoji Naoki
Cole Thomas W.
Epps Georgia
Roberts Mlotkowski & Hobbes
Sohn Seung C
Sokkia Co. Ltd.
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