DIOPTER ADJUSTMENT FOR OPTICAL DEVICE WITH OVERLAPPING LEFT-HANDED AND RIGHT-HANDED THREADS

Abstract

A diopter adjustment device for an optical device such as a riflescope includes a first tubular member having overlapping left-handed and right-handed external threads, a second tubular member has internal threads mated with either the left-handed or right-handed external threads of the first tubular member, and a stop nut threaded onto the first tubular member via internal threads that are of opposite handedness as the internal threads of the second tubular member. A diopter lens is mounted in one of the first and second tubular members and movable therewith relative to the other of the first and second tubular members to adjust a diopter setting or focus of the optical device. Because the internal threads of the nut and the second tubular member have opposite handedness, the nut provides greater resistance to inward movement of the diopter lens than conventional locking diopter adjustments.

Claims

1. A diopter adjustment device, comprising: a first tubular member having external threads; a second tubular member having internal threads, the first and second tubular members being threadably attached so that the internal threads of the second tubular member are mated with the external threads of the first tubular member; a lens mounted in one of the first and second tubular members; and a nut having internal threads and threaded onto the first tubular member, so that the internal threads of the nut are mated with the external threads of the first tubular member, the external threads of the first tubular member including right-handed external threads and left-handed external threads, the right-handed and left-handed external threads overlapping each other, and the internal threads of one of the second tubular member and the nut being left-handed and the internal threads of the other of the second tubular member and the nut being right-handed.

2. The diopter adjustment device of claim 1, wherein the nut is adjustable to bear against an end of the second tubular member and thereby stop further inward movement of the lens.

3. The diopter adjustment device of claim 1, wherein: the second tubular member is an eyeshell, the first tubular member is a diopter adjustment barrel, and the lens is securely mounted in the diopter adjustment barrel for movement therewith.

4. The diopter adjustment device of claim 1, wherein: the first tubular member is a scope housing, the second tubular member is an eyepiece housing, and the lens is securely mounted in the eyepiece housing.

5. The diopter adjustment device of claim 1, wherein the left-handed internal threads and the left-handed external threads are multi-start threads, and the right-handed internal threads and the right-handed external threads are single-start threads.

6. The diopter adjustment device of claim 1, wherein the left-handed internal threads and the left-handed external threads are single-start threads, and the right-handed internal threads and the right-handed external threads are multi-start threads.

7. The diopter adjustment device of claim 1, wherein the right-handed internal threads and the right-handed external threads are multi-start threads with a first number of starts, and the left-handed internal threads and the left-handed external threads are multi-start threads with a second number of starts.

8. The diopter adjustment device of claim 7, wherein the first number of starts is different from the second number of starts.

9. The diopter adjustment device of claim 1, wherein the right-handed external threads have a pitch that is equal to a pitch of the left-handed external threads.

10. The diopter adjustment device of claim 1, wherein the right-handed external threads have a pitch that is different from a pitch of the left-handed external threads.

11. The diopter adjustment device of claim 1, wherein the first tubular member includes a flange at a distal end, and the flange is knurled or textured.

12. The diopter adjustment device of claim 1, wherein an exterior surface of the nut is knurled or textured.

13. An optical sighting device including the diopter adjustment device of claim 1.

14. The optical sighting device of claim 13, wherein the optical sighting device is a riflescope.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG. 1 shows a prior-art diopter adjustment assembly of a riflescope including an internally threaded eyeshell, an internally threaded lock ring, and an externally threaded diopter assembly, all having right-handed threads.

[0011] FIG. 2 shows a portion of an eyepiece of a riflescope including a diopter adjustment mechanism according to an embodiment of the present invention.

[0012] FIG. 3 is an enlarged view of a portion of the diopter adjustment mechanism of FIG. 2, showing detail of overlapping left-handed and right-handed external threads on a barrel of a diopter adjustment subassembly of the diopter adjustment mechanism.

[0013] FIG. 4 is an exploded view of the diopter adjustment mechanism of FIG. 2.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0014] FIG. 2 illustrates a diopter adjustment device 100 according to a preferred embodiment, illustrated in the form of an eyepiece unit of a riflescope. Other portions of the riflescope, such as the main tube, turret knobs, objective, and other lenses are omitted from the figures, but are well understood to those skilled in the art. FIG. 4 is an exploded view of the diopter adjustment device 100. With reference to FIGS. 2 and 4, diopter adjustment device 100 includes a first tubular member, referred to herein as a diopter adjustment barrel 110, which has external threads 120 formed or cut therein. A lens 122 or lens system (also referred to herein as a diopter lens) is mounted within diopter adjustment barrel 110 for movement therewith, the diopter adjustment barrel 110 and lens 122 together forming a diopter adjustment subassembly 118. As best illustrated in FIG. 3, which is an enlarged view of a portion of FIG. 2, the external threads 120 include overlapping left-handed external threads 124 and right-handed external threads 126 that crisscross along at least a portion of the length of the diopter adjustment barrel 110. A second tubular member, referred to herein as an eyeshell 130, is provided with internal threads 132 (FIG. 3) which are sized to receive and mate with either the left-handed external threads 124 or the right-handed external threads 126 of the diopter adjustment barrel, depending on the desired handedness of the adjustment device 100. In the embodiment illustrated, the internal threads 132 of the eyeshell 130 are right-handed and mate with right-handed external threads 126, so that clockwise rotation of the diopter adjustment barrel 110 moves the lens 122 closer to eyeshell 130 and counterclockwise rotation of diopter adjustment barrel 110 moves lens 122 away from eyeshell 130, to thereby adjust a diopter setting or focus of the optical device. However, in another embodiment, the thread direction may be reversed so that the internal threads 132 of eyeshell 130 are left-handed and mate with the left-handed external threads 124 so that counter-clockwise rotation of diopter adjustment barrel 110 moves lens 122 closer to eyeshell 130.

[0015] A stop nut 140 (which is also sometimes referred to in the art as a jamb nut or locknut) has internal threads 144 that are of opposite handedness as the internal threads of the second tubular member (eyeshell 130), and is threaded onto the first tubular member (diopter adjustment barrel 110), so that the internal threads of the stop nut 140 are mated with the external threads 120 of the first tubular member. In the embodiment illustrated, the internal threads 144 of the stop nut 140 are left-handed and mate with the left-handed external threads 124 of the diopter adjustment barrel 110. The stop nut 140 is rotatable to move the stop nut 140 along the diopter adjustment barrel 110 to a selected position whereat the stop nut 140 bears against an end 148 (FIG. 4) of the eyeshell 130 to thereby stop further inward movement of the diopter lens 122 and secure it in position. The end 148 of eyeshell 130 and an axial side surface 152 (FIG. 4) of the stop nut 140 that faces end 148 may be roughened or textured to increase friction at the interface where stop nut 140 bears on the end 148 of eyeshell 130.

[0016] In another embodiment (not illustrated), the first tubular member having overlapping left- and right-handed external threads is a housing or main tube of a riflescope, or a portion thereof; the second tubular member (with internal threads) is an eyepiece housing or eyeshell; and the lens (diopter lens) is securely mounted in the eyepiece housing or eyeshell. In such an embodiment, the nut has internal threads of opposite handedness as the internal threads of the eyepiece housing.

[0017] In a riflescope, the diopter adjustment accommodates for differences in eyesight between users, and enables the user to adjust the focus of the eyepiece so the user sees a reticle of the riflescope (not illustrated) in sharp focus. As is well known in the art, the reticle of a riflescope is generally located at or displayed at an internal focal plane of the riflescope superimposed on an image of the distant scene. In riflescopes having significant optical magnification (e.g. greater than about 4×), a separate focus adjustment may be provided for moving other lenses of the riflescope, such as an objective lens or other lens between the objective and the focal plane, for focusing the distant scene at the location of the reticle. U.S. Pat. No. 6,005,711 of Mai et al., which is commonly assigned with the present application and incorporated herein by reference, describes a variable optical power riflescope with a side-focus control and an eyepiece threaded onto the main tube of the riflescope to provide a diopter adjustment.

[0018] Turning back to FIGS. 1-3, to use the diopter adjustment device 100 the user would typically back off the stop nut 140 away from the eyeshell 130 then adjust the diopter setting by twisting the diopter adjustment barrel 110 to achieve the desired sharp focus of the reticle. After the desired diopter setting is achieved, the user then rotates the stop nut 140 until it bears against the end 148 of the eyeshell 130 and tightens the stop nut 140 to secure the diopter setting against inadvertent adjustment. In the embodiment illustrated, the stop nut 140, which has left-handed internal threads 144, is tightened by rotating it counter-clockwise. Tightening the stop nut 140 against end 148 applies a preload which increases thread friction. Because the internal threads of the stop nut 140 and the eyeshell 130 have opposite handedness, the stop nut 140 provides greatly increased resistance to inward movement of the lens 122 (for example in response to recoil of a weapon to which the riflescope is mounted) than conventional locking diopter adjustments in which all threads are the same handedness, even when the mated threads of the diopter adjustment barrel 110 and eyeshell 130 are so-called “fast focus” threads having a relatively large pitch and/or lead.

[0019] For example, in one embodiment the right-handed external thread 126 of diopter adjustment barrel 110 and the right-handed internal thread 132 of eyeshell 130 may be multi-start threads, with 2, 3, 4, 6, 10 or more starts and having a relatively large lead enabling fast-focus performance; and the left-handed internal thread 144 of the stop nut 140 and the left-handed external thread 124 of diopter adjustment barrel 110 may be a single-start thread with a relatively fine pitch and lead. For example, in one embodiment the lead of the right-handed threads 126, 132 may be at least twice as large as the lead of the left-handed threads 124, 144. Alternatively, left-handed internal threads 144 and left-handed external threads 124 may be multi-start threads, and right-handed internal threads 132 and right-handed external threads 126 may be single start threads. In still another embodiment, the right-handed internal threads 132 (e.g. of eyeshell 130) and the right-handed external threads 126 (e.g., of diopter adjustment barrel 110) may be multi-start threads with a predetermined first number of starts (e.g., 2, 3, 4, 6, 10, or more starts), and the left-handed internal threads 144 of stop nut 140 and left-handed external threads 124 (e.g. of diopter barrel 110) may be multi-start threads with a predetermined second number of starts. The second number of starts may be different from the first number of starts. In one embodiment, the first number of starts is greater than the second number of starts.

[0020] Advantageously, the right-handed external threads 126 and the mating right-handed internal threads 132 of the second tubular member (eyeshell 130) have a pitch that is approximately equal to a pitch of the left-handed external threads 124 and mating left-handed internal threads 144 of the stop nut 140, to thereby create a regular pattern of overlapping threads on the surface of the diopter adjustment barrel 130 (or other first tubular member) as illustrated in FIGS. 2-4, which is visually distinctive. In an alternative embodiment (not illustrated), the pitch of the right-handed external threads 126 is different from the pitch of the left-handed external threads 124. In some embodiments, the lead of the right-handed external threads 126 may also be different from the lead of the left-handed external threads 124.

[0021] The diopter adjustment barrel 130 (first tubular member in this example) preferably includes at its distal end 158 a flange 160 that is knurled or textured to improve gripping when manually rotating the diopter adjustment barrel 130 to adjust the diopter setting. An exterior cylindrical surface 170 of stop nut 140 is preferably also knurled or textured to improve gripping.

[0022] The embodiments described above are described in the context of a riflescope including the diopter adjustment device 100. The diopter adjustment devices described herein may also be useful on other types of optical devices, such as binoculars, spotting scopes, and rangefinders.

[0023] It will be obvious to those having skill in the art that many changes may be made to the details of the above-described embodiments without departing from the underlying principles of the invention. The scope of the present invention should, therefore, be determined only by the following claims.