Firearms – Implements – Sight devices
Reexamination Certificate
2000-01-31
2002-03-05
Carone, Michael J. (Department: 3641)
Firearms
Implements
Sight devices
Reexamination Certificate
active
06351907
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to variable power telescopic sights having a side-mounted focus adjustment knob and, in particular, to such a sight having a side-mounted focus adjustment knob including a spiral cam mechanism for increasing the focus travel of the sight.
BACKGROUND OF THE INVENTION
Telescopic sights for rifles typically include eyepiece and objective lenses positioned at opposite ends of a tubular housing. Conventional variable optical power telescopic sights also include an erector lens positioned medially of the eyepiece and objective lenses and movable along a central longitudinal axis of the housing for adjustment of the optical power.
In these sights, an image focus adjustment compensating for variations in the distance from the marksman to the target is typically accomplished by longitudinal movement of the objective lens. One prevalent image focus adjustment implementation uses a threaded mounting ring that is coupled to the housing for rotation about the objective end of the housing. The marksman rotates the mounting ring, to adjust the position of a focusing element of the objective lens along the longitudinal axis of the housing.
This implementation is prone to image distortion caused by tilting of the objective lens during focus adjustment and makes it difficult to seal the ends of the housing to maintain within the telescopic sight a nitrogen gas charge necessary to prevent fogging and condensation on internal lens surfaces. This implementation also requires the marksman to stop viewing the target through the telescopic sight, move the rifle out of shooting position, and rotate the rifle to read markings on the outside of the housing or focusing ring which indicate the amount of focus adjustment. After viewing the focus ring adjustment indicator markings, the marksman then must reacquire the target.
A technique for varying the optical power of a telescopic sight is described in U.S. Pat. No. 3,058,391 of Leupold. This telescopic sight has an erector lens positioned between an objective lens and an eyepiece lens and adjustable along the longitudinal axis of the housing. It includes a field lens or collector lens located between the objective and the erector and movable in conjunction with and relative to movement of the power varying erector to compensate for focus effects resulting from movement of the erector. Movement of the collector and erector lenses to maintain focus during adjustment of the optical power of the telescopic sight is accomplished by turning a single adjustment ring concentrically mounted around the housing near the eyepiece end of the sight and connected to a cam sleeve mechanism within the interior of the sight housing.
Because bullet trajectory, wind conditions, and distance to the target can vary depending upon shooting conditions, quality rifle sights typically provide a mechanism for compensating for variations in these parameters by allowing the marksman to make small adjustments to the optical characteristics or the aiming of the sight relative to the rifle on which it is mounted. These adjustments are known as windage and holdover and are typically accomplished by lateral movement of the reticle within the telescopic sight, as shown in U.S. Pat. No. 3,058,391 of Leupold, or pivotal movement of lenses mounted to a pivot tube within the housing to divert the optical path of the observed light before it reaches the reticle, as shown in U.S. Pat. Nos. 3,297,389 and 4,408,842 of Gibson. In these designs, a marksman accomplishes adjustment of windage and holdover by turning a laterally protruding screw or turret that is operatively connected to the reticle or pivot tube. The range of adjustment for windage and holdover in these designs is limited by the space available within the housing for lateral movement of the reticle or pivotal movement of the pivot tube.
Variable power telescopic sights with side-mounted focus control knobs have recently been developed. These sights typically use the erector assembly and cam-sleeve mechanism to vary the power of the sight in accordance with the teachings of U.S. Pat. No. 3,058,391. To facilitate a side-mounted focus control knob, the objective lens system is split into two components, a fixed objective lens portion located at the objective end of the housing and a movable objective lens portion slidably mounted within the housing medially of the fixed objective and the erector assembly. The focus control knob protrudes laterally from the outer side of the sight housing opposite the windage adjustment turret and is mechanically coupled to the movable objective lens portion for adjusting the focus of the sight.
One known embodiment of the focus control knob is described in U.S. Pat. No. 4,643,542. This focus control knob includes an offset drive pin projecting within the interior of the housing and arranged so that rotation of the focus control knob results in orbital movement of the offset drive pin in a plane perpendicular to the axis of rotation of the focus control knob. The offset drive pin is engaged in an elongated slot formed in a link arm. The link arm is located within the interior of the housing and connected to the movable objective lens portion. The slot is oriented transversely of the longitudinal axis of the housing. The coupling between the offset drive pin and the link arm is such that orbital movement of the offset drive pin imparts movement to the movable objective lens portion along the longitudinal axis. One shortfall of the offset drive pin mechanism is that it results in movement of the movable objective lens portion at varying rates depending upon the position of the focus control knob. Because the offset drive pin moves orbitally, it moves along the longitudinal axis quickly when the adjustment knob is in the middle of its rotation, i.e., when the offset drive pin is near the top of its orbital arc, and slowly when the adjustment knob is near either limit of its 180 rotation.
SUMMARY OF THE INVENTION
An object of the invention is, therefore, to provide a telescopic sight having a side mounted focus control knob that allows an observer to adjust the focus of the sight and view a readout of the focus adjustment from the observing position without interrupting observation of the target through the sight.
Another object of the invention is to provide such a telescopic sight in which the side-mounted focus control knob includes a spiral cam mechanism that moves a movable objective lens portion longitudinally within a housing of the sight.
A further object of the invention is to provide such a focus control knob that rotates more than 180 degrees in response to which the movable objective lens portion moves with a predetermined longitudinal movement profile.
Yet another object of the invention is to provide a focus control knob for rifle-mounted telescopic sight that is of simple and rugged construction and is capable of withstanding without degradation of accuracy or precision the handling and environmental conditions to which hunting and military rifles are exposed.
These and other objects and advantages of the invention are accomplished in a telescopic sight that includes an elongate tubular housing that holds at opposite ends an objective lens system and an eyepiece lens, a manually adjustable movable erector lens for varying optical power, and a side mounted focus control device located medially along and protruding laterally from the outside of the housing for focusing the sight. The erector lens is located medially of the objective lens system and the eyepiece and pivotally mounted to a pivot tube within the housing to provide for windage and holdover adjustments made by manually adjustable aiming control devices.
In one type of telescopic sight, the objective lens system is split to facilitate side-mounted focus control and includes a fixed objective lens portion positioned at an objective end of the housing and a movable objective lens portion positioned inside the housing medially of the fixed objective lens portion and the erector. Th
Buckley Denise J
Leupold & Stevens, Inc.
Rives LLP Stoel
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