Radiant energy – Photocells; circuits and apparatus – Photocell controls its own optical systems
Reexamination Certificate
1999-04-09
2001-02-27
Lee, John R. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Photocell controls its own optical systems
C356S370000
Reexamination Certificate
active
06194694
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a surveying instrument employing a sighting telescope having an auto-focusing function.
Conventionally, a surveying instrument such as an electric distance meter, an electronic theodolite, and the like have been known. The distance meter is for measuring a distance to an aiming point, and the theodolite, or an angle measuring instrument is for measuring horizontal and vertical (elevational) angles between a reference point and an aiming point.
In such a surveying instrument, a sighting telescope is provided for accurately sighting the instrument on an aiming point. By aligning the sighting telescope so that the aiming point is located at the center of field of view, the axis of distance measuring or measuring the horizontal and elevational angles is aligned to intersect the aiming point.
In order to view the aiming point clearly within the field of view of the sighting telescope, a focusing mechanism is provided. The focusing mechanism is to be manipulated so that an in-focus image of the aiming point is formed. To ease the focusing operation, recently, auto-focusing system have been employed in the sighting telescopes.
With the auto-focusing function, the focusing condition of the sighting telescope is automatically adjusted. Thus, the auto-focusing function makes the operator free from troublesome manipulation of focusing mechanism, and allows the operator to concentrate on centering the aiming point in the field of view of the sighting telescope.
In such a sighting telescope, when surveying is performed, a reflector is located at the aiming point. Generally, a corner cube is used as the reflector. The corner cube reflects an incident ray of light along the same direction thereof. Accordingly, when an operator sights the sighting telescope on the corner cube, and the optical axis of the sighting telescope intersects a reflection surface of the corner cube, the auto-focusing system focuses on a virtual image of the telescope formed by the corner cube. That is, the auto-focusing system focuses on an object (i.e., the telescope) located at twice a distance of the corner cube. Then, the corner cube in the field of view is fuzzy (out-of-focus), and the operator has to manipulate the focusing system, even if the auto-focusing system is employed, to focus on the corner cube.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a surveying instrument employing a sighting telescope having an auto-focusing system which enables an operator to re-focus on the reflector if the auto-focusing system focuses on the virtual image of the telescope formed by the reflector.
For the above object, according to the invention, there is provided a surveying instrument, which is provided with a sighting telescope that is utilized to sight on a reflector (which may be a corner cube) located at an aiming point; an auto-focusing system which adjusts a focusing state of an image in a field of view of the sighting telescope; a switch; and a correction system that controls the auto-focusing system, in response to an operation of the switch, to correct a focusing state of the image of the sighting telescope from a first state to a second state, the first state being a state where an object whose object distance is a first distance is focused on, the second state being a state where an object whose object distance is a second distance is focused on, the second distance being substantially a half of the first distance.
With the surveying instrument having the above constitution, if the telescope focuses on the virtual image of itself formed by the reflector located at the aiming point, the focusing state can quickly changed such that the reflector is focused on only by depressing a single switch.
Optionally, the auto-focusing system may include: a focusing lens; a defocus amount detecting system that detects a defocus amount with respect to a predetermined image receiving plane of the sighting telescope; and a first driving amount calculating system that calculates a driving amount of the focusing lens of the auto-focusing system based on the defocus amount.
Further, the correction system may include: a lens position detecting system that detects a first position of the focusing lens when focusing on an object located at the first distance; a lens position determining system that determines, based on the first position, a second position of the focusing lens for focusing on an object located at the second distance; and a lens driving system that drives the focusing lens to the second position.
Furthermore, the lens position determining system may include: a first distance calculating system that calculates the first distance based on the first position detected by the lens position detecting system; and a lens position calculating system that calculates the second position for focusing on an object located at a distance which is a half of the first distance, wherein the lens driving system drives the focusing lens by an amount which is equal to a difference between the second position and the first position.
The surveying instrument may include a electronic theodolite and/or a distance metering device. In particular case, the surveying instrument is a total station.
REFERENCES:
patent: 5053801 (1991-10-01), Ishida et al.
patent: 5243375 (1993-09-01), Ishida et al.
patent: 5796517 (1998-08-01), Sensui et al.
patent: 5844231 (1998-12-01), Suzuki et al.
patent: 5856663 (1999-01-01), Suzuki et al.
patent: 5856664 (1999-01-01), Suzuki et al.
patent: 5886340 (1999-03-01), Suzuki et al.
patent: 5936736 (1999-08-01), Suzuki et al.
Asahi Kogaku Kogyo Kabushiki Kaisha
Greenblum & Bernstein P.L.C.
Lee John R.
LandOfFree
Surveying instrument does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Surveying instrument, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Surveying instrument will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2597253