Firearms – Implements – Sight devices
Reexamination Certificate
1999-10-14
2001-08-07
Jordan, Charles T. (Department: 3641)
Firearms
Implements
Sight devices
C089S203000, C359S694000, C359S422000, C359S429000
Reexamination Certificate
active
06269580
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a motor-driven focusing apparatus which has a manual operating switch to finely adjust the focal point of a telescopic optical system of a sighting telescope incorporated in a surveying instrument such as an automatic level, a transit, a theodolite, etc.
2. Description of the Related Art
A conventional surveying instrument such as an automatic level (auto-level), a transit, a theodolite, etc., is generally provided with a sighting telescope (collimating telescope), a level and a measuring device which measures a rotational angle, a descending angle, and an ascending angle, etc. When this type of surveying instrument is used, the sighting telescope is positioned horizontally and subsequently the horizontal and vertical adjustments for the sighting telescope are performed. Thereafter, the sighting telescope is aimed at a reference object or a reference point so that the reference object is sighted by a surveyor.
For instance, the optical system of the sighting telescope of an automatic level includes an objective lens group, a focusing lens group and an eyepiece, arranged in that order from the object side. The position of the focusing lens group is adjusted depending on the object distance, so as to form a sharp object image on the reticle provided on the focal plane. The object image formed on the reticle can be viewed through the eyepiece.
The amount of movement of the focal point per unit amount of movement of the focusing lens group varies depending upon the axial position of the focusing lens group on the optical axis thereof.
FIG. 7
shows an example of the relationship between the axial position of the focusing lens group (the object distance) and the FL factor. The FL factor represents the amount of movement of the focal point when the focusing lens group moves by a unit amount of movement; namely, the FL factor represents the value of the amount of movement of the focusing lens group divided by the amount of movement of the focal point. The vertical axis of the graph shown in
FIG. 7
represents the FL factor while the horizontal axis of the graph represents the axial position of the focusing lens group wherein the image of an object positioned at the indicated object distance (meters) is focused on the reticle. It can be understood from the graph shown in
FIG. 7
that the amount of movement of the focal point is not always proportional to the amount of movement of the focusing lens group.
Due to this fact, in the case of a sighting telescope provided with a motor-driven focusing apparatus (auxiliary focusing apparatus) used for finely adjusting the focal point to form a sharp object image on the reticle by operating a manual operating switch (e.g., a controlling knob or lever) of the motor-driven focusing apparatus after the object is brought into focus by the autofocusing mechanism of the sighting telescope, it is difficult to finely adjust the focal point to form a sharp object image on the reticle with the motor-driven focusing apparatus since the amount of movement of the focal point per unit amount of movement of the focusing lens group varies depending on the axial position of the focusing lens group on the optical axis thereof.
SUMMARY OF THE INVENTION
The primary object of the present invention is to provide a motor-driven focusing apparatus of a sighting telescope that makes it possible to finely adjust the focal point easily.
To achieve the object mentioned above, according to an aspect of the present invention, there is provided a motor-driven focusing apparatus of a telescope, including: a telescopic optical system which includes a focusing lens group guided along an optical axis; a motor-driven lens moving device which drives the focusing lens group along the optical axis; a manual operating switch for actuating the motor-driven lens moving device; and a lens-control device for controlling the motor-driven lens moving device when the manual operating switch is turned ON, so that the moving amount per unit time of a focal point of the telescopic optical system, that is caused by a movement of the focusing lens group, is kept substantially at a constant speed regardless of the position of the focusing lens group on the optical axis, the constant speed being selected from one or more constant speeds.
According to this structure, the amount of movement of the focal point (i.e., the amount of variation in the degree of image-blurring) is substantially proportional to the manipulated variable of the manual operating switch regardless of the axial position of the focusing lens group on the optical axis, which makes it possible to finely adjust the focal point easily.
Preferably, the manual operating switch includes a speed changing function that can change the moving amount per unit time of a focal point of the telescope via the motor-driven lens moving device by the constant speed selected from one or more constant speeds.
Preferably, there is also provided a lens-position detector for detecting the position of the focusing lens group on the optical axis; and a memory in which compensation data for compensating an amount of driving of the focusing lens group for each position of the focusing lens group on the optical axis within a movable range of the focusing lens group is stored. The lens-control device inputs data from the compensation data stored in the memory for compensating the amount of driving of the focusing lens group for a position of the focusing lens group that is detected by the lens-position detector, so as to control the motor-driven lens moving device in accordance with the input data.
Preferably, there is also provided a lens-position detector for detecting the position of the focusing lens group on the optical axis; and a memory which stores a formula for calculating compensation data for compensating an amount of driving of the focusing lens group for each position of the focusing lens group on the optical axis within a movable range of the focusing lens group. The lens-control device calculates the compensation data with the formula in accordance with the position of the focusing lens group that is detected by the lens-position detector to control the motor-driven lens moving device in accordance with the compensation data.
Preferably, the motor-driven focusing apparatus is incorporated in a surveying instrument.
Preferably, the manual operating switch includes a rotatable control lever.
Preferably, the telescope includes an autofocusing system having an AF start switch that is actuated to bring a sighting object into focus upon the AF start switch being turned ON.
According to another aspect of the present invention, there is provided a sighting telescope incorporated in a surveying instrument, including: a telescopic optical system which includes a focusing lens group guided along an optical axis; an autofocusing system which starts moving the focusing lens group along the optical axis to bring a sighting object into focus upon an AF start switch being turned ON; a motor-driven auxiliary focusing apparatus that moves the focusing lens group along the optical axis to finely adjust the position of the focusing lens group on the optical axis, the motor-driven auxiliary focusing apparatus including an manual operating switch that is operated to actuate the motor-driven auxiliary focusing apparatus; and a lens-control device for controlling the motor-driven auxiliary focusing apparatus, when the manual operating switch is turned ON, so that the moving amount per unit time of a focal point of the telescopic optical system, that is caused by a movement of the focusing lens group, is kept substantially at a constant speed regardless of the position of the focusing lens group on the optical axis, the constant speed being selected from one or more constant speeds.
Preferably, the manual operating switch includes a speed changing function that can change the moving amount per unit time of a focal point of the telescope via the motor-driven lens moving device b
Asahi Kogaku Kogyo Kabushiki Kaisha
Buckley Denise J
Greenblum & Bernstein P.L.C.
Jordan Charles T.
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