Binocular alignment

A binocular viewing device including means for resiliently mounting a prism seat to the binocular body within an enclosed chamber consisting of at least three elongated fasteners spaced about the periphery of the prism seat, with means associated with each fastener for resiliently engaging a first surface of the prism seat to urge the prism seat into fixed contact with the body, and at least one adjusting member extending through the body into the chamber from the outside, the inner end of the adjusting member adapted upon rotation for axial movement relative to the body for engagement upon a second surface of the prism seat in a manner to displace the prism seat from contact with the body, thereby to change the relationship of the plane of the prism seat to the line of viewing from ocular lens to objective lens for changing alignment of the optical system.

BACKGROUND OF THE INVENTION 
This invention relates to binoculars. 
In the final stages of manufacturing, the optical system of a new binocular 
must be placed in alignment so that the image will be undistorted when 
viewed through the eye pieces. 
Several alignment procedures have been used in the manufacture of Japanese 
binoculars: 
I. The so-called "orthodox" method comprises the use of a leaf or foil 
underneath the prism and using the eccentric ring of the objective to 
effect the adjustment. 
II. Next to the "orthodox" method, the most stable system involves mounting 
the prism seat on its three mutually spaced pads within the prism chamber 
by means of three pairs of screws, each pair comprising a set screw and an 
adjusting screw. Use of this arrangement has been known to distort the 
prism seat some times causing prism chipping. 
III. As an alternative to the foregoing, the edges of the prism seat are 
mounted on the pads by means of single screws with coil springs placed 
between the bottom surface of the seat and the top surface of the pad. 
Tightening or loosening of the screws causes adjustment of the seat and 
correspondingly of the prisms. This arrangement is fairly easy to use but 
not nearly so stable as the above. 
IV. In a fourth system, a prism is tiltably held in its seat, the latter 
being immovably fastened to the interior wall of the chamber. An adjusting 
screw pierces the chamber wall and bears against the side of the prism. 
Turning the screw in or out controls the tilt of the prism for alignment 
purposes. Since the wall is thin it is difficult to prevent air leakage 
around the adjusting screw and the integrity of the seal of the chamber is 
jeopardized. Furthermore, the system inherently lacks stability, although 
it is the only one permitting adjustment of the alignment after the device 
has been assembled. 
Objects of the present invention include providing a structural 
configuration that allows stable prism alignment without endangering the 
seal of the enclosed body cavity; that reduces the danger of introducing 
tension to the prism seat with the possibility of chipping the prism; that 
provides for stable alignment; and that can be finely adjusted even by a 
relatively unskilled worker. 
SUMMARY OF THE INVENTION 
In accordance with the invention there is provided in a binocular viewing 
device having a body defining an enclosed chamber, a prism seat disposed 
within the chamber and mounted to the body, an optical system including 
prisms disposed upon the prism seat, and an ocular lens and an objective 
lens positioned at opposite ends of the chamber for viewing therethrough 
the following improvement. 
Means are provided for resiliently mounting the prism seat to the body 
comprising at least three elongated fasteners spaced about the periphery 
of the prism seat, with means associated with each fastener for 
resiliently engaging a first surface of the prism seat to urge the prism 
seat into fixed contact with the body, and at least one adjusting member 
extending through the body into the chamber from the outside, the inner 
end of the adjusting member adapted upon rotation for axial movement 
relative to the body for engagement upon a second surface of the prism 
seat in a manner to displace the prism seat from contact with the body, 
thereby to change the relationship of the plane of the prism seat to the 
line of viewing from the ocular lens to the objective lens for changing 
alignment of the optical system. 
In preferred embodiments, the adjusting screw is disposed at an acute angle 
to the axis of the associated setting screw, preferably at an angle of 
about 35.degree.. 
These and other features and advantages of the invention will be understood 
from the following detailed description of a preferred embodiment taken in 
conjunction with the annexed drawings and appended claims.

DESCRIPTION OF PREFERRED EMBODIMENT 
One of the two prismatic telescopes of the pair which comprise a binocular 
embodying the invention is shown in the two views of the drawing. Since 
the other telescope is for all intents and purposes identical it has been 
omitted. 
Housing 12 may be hinged by hinge 13 to a corresponding housing (not 
shown). The housing 12 defines an enclosed chamber 14. At the rear of the 
chamber are ocular lenses 16 in eyepiece 18, and, at the front of the 
chamber, is disposed the objective lens 20. 
Mounted within the chamber is a prism seat 22 which is supported upon three 
separate pads 24, 26, 28 extending from the housing body, 
circumferentially spaced about the wall of the chamber. The prism seat is 
mounted by means of set screws 30 extending through the seat into threaded 
holes 32 provided in the pads. A resilient spring 34 is disposed upon the 
shaft of each set screw between the screw head and the first, or upper, 
surface 35 of the prism seat. When assembled, the springs are under 
compression and apply force to the seat to urge the second surface 38 of 
the seat against the pad. 
Supported upon the first and second opposite surfaces of the prism seat are 
the usual first and second prisms, 40, 42 respectively. The ocular lens, 
objective lens and prisms are selected and positioned relative to each 
other according to well-known procedures for providing the desired optical 
effect for viewing along the line of sight, A, through the lenses and the 
prisms. During the manufacturing and assembling processes, the lenses and 
prisms are disposed in positions to provide alignment therebetween that is 
roughly correct for the desired optical effect. For many reasons, 
including, e.g., variations in materials or dimensions or, possibly faulty 
workmanship, and the like, it has been necessary in the industry to 
provide means for final alignment of the optical system after assembly. 
The binocular viewing device of the invention is provided with adjustable 
means that permit fine alignment after assembly without violation of the 
enclosed chamber. 
As seen in the drawings, a threaded bore 50 extends through the body of the 
housing penetrating seat support pad 24 and opening on the upper surface 
of the pad lying beneath the second surface 38 of the seat 22. A threaded 
adjustment screw 52 is threadedly engaged within the bore and is rotated 
to a position leaving the head recessed within the housing and the tip 
recessed from engagement with the surface 38 of the seat. The screw 
effects an enclosed seal with the internal surface of the bore so as not 
to affect adversely the integrity of the enclosed chamber 14. This is 
because the bore is of substantial length and subject to ready sealing 
against passage of air. 
To effect alignment of the optical system, the adjustment screw is rotated 
to cause it to advance axially along axis, C, into contact with the seat 
surface. Continued rotation urges the seat off the pad, overcoming the 
resilient force applied by the opposed spring, thus changing the angle of 
the plane of the prism seat relative to the line of sight between the 
ocular and objective lenses. The adjustment screw may be rotated in either 
direction as desired, to raise or lower the seat with respect to the pad 
to achieve the desired alignment. 
The adjustment screw 52 is disposed at angle S to the axis, D, of the set 
screw 30, preferably of the order of about 35.degree.. This relationship 
results in a fractional ratio of movement of the seat along axis D to 
movement of the adjustment screw along axis C to enable fine adjustment of 
optical system alignment, even by a relatively unskilled worker without 
placing any strain on the prisms or impairing the seal of the chamber. 
While there is herein disclosed and described a presently preferred 
embodiment of the invention, it nevertheless will be understood that the 
same is by way of illustration and not limita- tion and the scope of the 
invention is to be measured only by the proper interpretation of the 
appended claims. 
Other embodiments are within the following claims, for example more than 
one adjusting member may be employed.