Mechanical coupler for eyepieces

A mechanical coupler for connection to the eyepiece of an optical device. The coupler includes a body with an axially extending cylindrical wall that forms a socket with a spanning portion of the body. The cylindrical wall and body center and axially align the coupler and the eyepiece. A C-shaped clamping member has a central portion that is affixed to the wall and essentially tangentially extending free end portions that produce a side opening structure. When an eyepiece is inserted from the side, it wedges the free ends of the clamping member axially thereby producing internal restoring forces in the clamping member. When the eyepiece is seated in the socket, the free ends return toward a relaxed position and produce a clamping force that affixes the coupler axially to the eyepiece while permitting relative rotation between them.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention generally relates to accessories for joining optical devices 
and more particularly to adapters or couplers for interfacing an optical 
device to an eyepiece. 
2. Description of Related Art 
Eyepieces are associated with a number of optical devices including, as 
examples, endoscopes and borescopes. The term "endoscope" generally 
denotes a class of optical devices used for examining the internal 
cavities of the human body. The term "borescope" generally denotes a class 
of analogous devices for examining internal cavities in machinery or other 
nonhuman areas. Endoscopes and borescopes, have the same basic structure. 
Each contains an objective lens for gathering an image, one or more 
intermediate relay lenses or fiber optics for relaying the image through 
an elongated tube and eyepiece optics for allowing an individual to view 
the image directly. 
The eyepiece optics in endoscopes and borescopes generally have a similar 
basic construction. Typically eyepiece optics include an eyepiece housing 
with a central cavity for any optical elements required by the eyepiece. 
Externally the eyepiece housing has a neck portion for attachment to an 
elongated tube from the endoscope or borescope. A frusto-conical or other 
conoidally-shaped housing section then flares from its distal end to a 
proximal end and terminates at a cylindrical peripheral flange portion. 
During direct viewing, an individual places his or her eye at this 
peripheral flange portion, that may or may not contain a viewing window. 
Eyepieces differ by having diverse diameters and by having specially shaped 
conoidal or flared housing surfaces. These differences may result from 
requirements of the optical elements contained in the eyepiece or merely 
from an aesthetic design consideration. Even frusto-conical or flared 
housing sections of different eyepiece housings may vary for a given 
diameter eyepiece among eyepieces supplied by different manufacturers. 
In many applications it is highly desirable to connect another device to 
the eyepiece. These devices may include photographic or television cameras 
or beam splitters for permitting two or more individuals to view an image 
simultaneously or to allow one individual to view the image directly while 
a television camera records the image simultaneously. Sometimes an 
individual has a preference for an eyepiece of a particular size the 
differs from the size of the eyepiece associated with the endoscope, 
borescope or the like. In both situations it is desirable to have an 
adapter that will attach the eyepiece of the desired size or a coupler 
that will attach a diverse optical device to an eyepiece associated with 
the endoscope or borescope. In the following discussion the term "coupler" 
is meant to include any such coupling devices or adapters. 
Several couplers have been proposed for mechanically coupling an optical 
device to an eyepiece including those disclosed in the following U.S. Pat. 
Nos. 
4,066,330 (1978) Jones 
4,305,386 (1981) Tawara 
4,318,395 (1982) Tawara 
4,740,058 (1988) Hori 
The Jones patent discloses an endoscope eyepiece with an opto-mechanical 
coupler. A spring-biased cam ring mounted on the coupler rotates to 
retract retaining studs and integral heads radially outward. When the 
studs are retracted the eyepiece can pass between the heads for connection 
to or separation from the eyepiece. When the cam ring is released, a 
spring biases it to a stable position and thereby moves the studs radially 
inward until the heads engage the flared surface of the eyepiece housing. 
This action clamps the eyepiece to and centers the eyepiece on the 
coupler. 
The Tawara-386 patent discloses an endoscope accessory mounting device, or 
coupler, with a spring-biased cam ring that controls the position of 
axially aligned, radially extending plate cams. When the cam ring is 
rotated, the eyepiece can freely pass into or separate from an eyepiece 
receiving socket in the accessory mounting device. When the eyepiece is 
located in the socket and the cam ring is released, springs displace the 
cam ring to its stable position and the cam plates rotate into engagement 
with the flared surface of the eyepiece thereby to clamp and center the 
accessory mounting device with respect to the eyepiece. 
The Tawara-395 patent also discloses an endoscope coupler with 
spring-biased axially aligned cam plates that are biased against a 
radially acting spring biased plunger. In this coupler the eyepiece snaps 
into the coupler by driving the cam plates away from a central axis and 
compressing the springs on the cam plates. When the eyepiece seats in a 
socket, the springs drive the cam plates against the flared surface of the 
eyepiece to clamp and center the coupler with respect to the eyepiece. An 
individual compresses the radially acting, diametrically opposed plungers 
to move the cam plates to an open position when it is desired to separate 
the coupler from the eyepiece. 
The Hori patent discloses an optical mechanical coupler with a C-shaped 
clamping member that is axially displaced from a clamping surface and 
operated by a locking ring or clamp member. When the clamp member rotates 
to one extreme position it axially displaces the C-shaped clamping member 
from the clamping surface. An eyepiece can then be inserted from the side. 
A reverse rotation of the clamp member displaces the C-shaped clamping 
member into the eyepiece thereby to clamp and center the coupler with 
respect to the eyepiece. 
Over the years the use of these and other mechanical couplers for eyepieces 
have led to the establishment of a number of desirable coupler criteria. 
Specifically, the attachment and separation processes must be simple and 
be capable of being performed with one hand. It should be possible to 
rotate the coupler with respect to the eyepiece. The coupler must be easy 
to clean and, in the case of endoscopes, be easy during use to sterilize. 
It must be inexpensive to produce, and reliable in use. Further, it should 
be possible to attach a single coupler to eyepieces of a given nominal 
diameter having diverse cross-sections or forms through the flared housing 
portions. 
Prior art couplers have exhibited some of these criteria, but not all of 
them. For example, The Tawara-395 patent coupler enables one-handed 
operation. The Jones and Tawara patents permit rotation between the 
eyepiece and the coupler. However, each of the above-described structures 
requires the assembly of a large number of components in the form of cam 
plate studs, Springs, rotatable control members, plungers and other 
elements. These structures are complicated, increase the manufacturing 
complexity and are subject to failure when debris accumulates in the 
operative mechanism during normal use, particularly in medical 
applications. Such couplers can not readily be repaired on site. A 
customer must maintain an inventory of such couplers or must be capable of 
operating whenever one of these couplers is at the factory for repair. 
With particular respect to endoscopes, the sterilization process is 
complicated because the mechanisms can trap solution making it difficult 
to assure that all the sterilizing solution has been evaporated or 
removed. Thus none of these couplers exhibit all the desirable criteria. 
Moreover, none of these couplers incorporate a simple, reliable structure. 
SUMMARY 
It is an object of this invention to provide a simple, reliable coupler for 
an eyepiece that contains no moving parts. 
Another object of this invention is to provide a simple, reliable coupler 
for an eyepiece that is adapted for one-handed, quick attachment and 
release operations. 
Still another object of this invention is to provide a simple, reliable 
coupler for an eyepiece that is adapted for simplifying cleaning and 
sterilizing operations. 
Yet another object of this invention is to provide a simple, reliable 
coupler for an eyepiece that centers and aligns the eyepiece and the 
coupler and that accepts a wide range of eyepiece configurations. 
Still yet another object of this invention is to provide a simple, reliable 
coupler for an eyepiece that centers and aligns the coupler and the 
eyepiece and that permits relative rotation between the eyepiece and the 
coupler. 
Yet still another object of this invention is to provide a simple, reliable 
coupler for an eyepiece that centers and aligns the coupler and the 
eyepiece, that permits relative rotation between the eyepiece and the 
coupler, and that allows the angular position between the eyepiece and the 
coupler to be fixed. 
A mechanical coupler constructed in accordance with this invention enables 
an image transmitted along an optical axis from an eyepiece associated 
with a first device to be received by a second device. The mechanical 
coupler includes a body with a first end portion that attaches to the 
eyepiece and a second axially-spaced portion that attaches to the second 
device. The body includes, at the first end portion, a cylindrical wall 
that centers the eyepiece on a coupler axis and an annular surface that 
abuts a cylindrical eyepiece flange portion of the eyepiece for aligning 
the coupler and optical axes. An integral axially-resilient clamp member 
attached to the cylindrical wall and the body form a side-opening 
receptacle for receiving the eyepiece. Free end portions of the clamp 
member deflect axially as the eyepiece is inserted into the receptacle. 
When the eyepiece seats in the receptacle, a restoring force, produced in 
the clamp when the free ends deflect, allows the free ends to engage the 
flared housing and clamp the cylindrical flange against the coupler body.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
FIGS. 1 through 5 depict one embodiment of a coupler in the form of an 
optical eyepiece adapter 10 that incorporates this invention and provides 
a simple structure for adapting an eyepiece having first characteristics, 
such as diameter and form, to an eyepiece having different 
characteristics. As shown particularly in FIGS. 1 through 3, the optical 
eyepiece adapter 10 includes a body 11 composed of machinable, thermally 
stable, lightweight material. For endoscopes the materials must 
additionally be colorfast and chemically inert. Such materials for the 
body 11 include aluminum, stainless steel and certain acetal compounds 
such as marketed under the name Delrin.RTM.. 
One end section 12 of the body 11 includes an integral eyepiece 13 with a 
peripheral flange 14 and a flared conoidal housing 15 of a given form. The 
peripheral flange 14 constitutes a viewing end 16 that enables an 
individual to view an image transmitted through an aperture 17 that 
extends along a coupler axis 18. FIGS. 1 through 3 disclose a specific 
eyepiece known as a "B-mount" eyepiece. 
Another end section 20 of the body 11 is adapted for connecting to an 
eyepiece 21, as shown in FIGS. 4 and 5. This eyepiece 21 includes a 
housing portion 21A having a flared surface with its base contiguous a 
cylindrical flange portion 21B that extends axially from the flared 
housing portion. The cylindrical flange 21B has a predetermined axial 
dimension or depth. The other, or distal, end of the housing 21A 
terminates at a neck portion 21C. A central aperture 22 extends through 
the eyepiece 21 along an optical axis 23. 
Referring again to FIGS. 1 and 2, the body 11, at the end section 20, has 
an axially extending wall 24 with a radial end surface 25 and an inner 
axially extending, cylindrical wall surface 26. The inner wall surface 26 
conforms to the eyepiece central flange 21B as shown in FIGS. 4 and 5 for 
centering the eyepiece 21 on the coupler axis 18. The cylindrical wall 24 
then forms a socket or receptacle 27 having as a base or abutting surface 
a radially extending planar annular wall 30. The wall surface 30 is 
centrally located with respect to the cylindrical wall 24 and abuts the 
cylindrical flange portion 21C to align the coupler axis 18 with the 
optical axis 23. In this particular embodiment the wall 30 comprises a 
radially extending planar surface. However, the wall 30 could have a 
conical form to provide edge contact, with respect to the cylindrical 
flange 21B, rather than a surface contact with the flange 21B as shown in 
the Figures. 
The cylindrical wall 24 additionally comprises an arcuate, axially 
extending step 31 with a top surface 32 and an inner surface 33. In this 
particular embodiment the step has a semicircular configuration and 
extends approximately 180.degree. around the top 25 of the cylindrical 
wall 24. As apparent from the Figures, the depth of the cylindrical wall 
24 and the step 31 corresponds to the height of the flange 21B. 
The step 31 supports an integral, axially resilient C-shaped clamping 
member 34 that captures the eyepiece 21 in the socket 27 as shown 
particularly in FIGS. 4 and 5. The clamping member 34 has a central 
arcuate section 35 with spaced apertures 36. Machine screws 37, or other 
fastening devices, engage threaded apertures 38 in the step 31 thereby to 
clamp the central portion 35 against the seat 31. 
In a preferred form of this structure, the radial dimension of the central 
portion 35 exceeds the radial dimension of the step 31. When the clamping 
member 34 is properly positioned, an inner edge extends radially inward 
from an inner surface 33 of the step 31 thereby to form an overhanging lip 
39. The lip 39 engages the conoidal housing 21A of the eyepiece 21 as 
disclosed more fully later. 
The clamping member 35 additionally contains two free ends 40 and 41 that 
extend essentially tangentially from the arcuate central portion 35 to 
complete the "C" shape. Each of the free ends 40 and 41 has an inwardly 
facing edge 42 with a chamfer 43 along the bottom edge thereof. The inner 
edge 42 extends radially inward to overlap the surface 30; it is spaced 
axially from the surface 30. 
The clamping member 34 is composed of a material that has the same 
characteristics as the body 10. It also must be of a material that enables 
the free ends 40 and 41 to deflect relative to the central portion 35 and 
that generates a restoring force during such a deflection. Acetal 
compounds, such as Delrin.RTM. are particularly adapted for use as a 
clamping member. 
The clamping member 34, as shown most clearly in FIGS. 1 and 2, forms a 
side-opening structure and the free ends 40 and 41 lie in the plane of the 
clamping member 34 when the socket 27 is empty. The side opening allows an 
individual to slide an eyepiece 21 into the socket 27 from the side, from 
the left in FIGS. 1 through 5. As shown in FIG. 4, when this occurs, the 
flared portion 21A, that is proximate the flange 21B, engages and axially 
deflects the free ends 40 and 41. Specifically, that proximate portion of 
the housing 21A engages the chamfer 43 on the free ends 40 and 41. As the 
flange 21B must ride over the top surface 25 of the cylindrical wall 24 
during this motion, the housing 21A wedges the free ends 40 and 41 and 
deflects them upward about an axis through the outer fastenings 37. 
During this deflection the material in clamping member 34 develops its 
internal restoring force. When the eyepiece 21 centers in the socket 27, 
the flange 21B drops to mate against the surface 30 and the restoring 
force returns the free ends 40 and 41 toward a normal position. However, 
interference between the chamfered edges 43 and the housing 21B prevent a 
complete return, so a residual restoring force continues to act on the 
free ends 40 and 41. This residual force produces an axially directed 
clamping force along the edges at proximate, diametrically opposed 
positions on the housing 21. The combination of this clamping action and 
the interference between the lip 39 and the housing 21A capture the 
eyepiece flange 21B in the socket 27. The inner cylindrical wall 26 
prevents any relative lateral motion between the eyepiece 21 and the 
adapter 10. However the adapter 10 is free to rotate about the coupler 
axis 18 and optical axis 23 with respect to the eyepiece 21. 
Referring to FIGS. 1 through 3, the adapter 10 may contain a mechanism for 
locking the adapter 10 to the eyepiece 21. In this particular embodiment a 
radially extending threaded aperture 45 passes through an end portion of 
the cylindrical wall 24 and step 31 and carries a locking screw 46 or like 
structure. When the locking screw 46 advances radially toward the axis 18, 
it engages the flange 21B and prevents rotation between the eyepiece 
adapter 10 and the eyepiece 21. 
In use, the eyepiece adapter 10 shown in FIGS. 1 through 5 can be clamped 
to an eyepiece, such as the eyepiece 21 of an endoscope, borescope or the 
likely, merely by holding the eyepiece in one hand and snapping the 
eyepiece adapter 10 onto the eyepiece 21 with the other hand. Once the 
eyepiece adapter 10 is mounted on the eyepiece 21, it is a simple matter 
to lock the eyepiece adapter in place merely by turning the locking screw 
46, which can be done independently with one hand. Finally, a separation 
procedure, that is the reverse of the attachment procedure, is readily 
accomplished with a single hand. Any sideways motion that might be induced 
during such an attachment or separation is limited. Specifically, forces 
tending to pivot the distal end would be applied to the proximal end, and 
the hand that holds the eyepiece would act as a pivot. The length of the 
lever arm between the point of force application and the pivot will be 
very short with respect lever arm between the pivot and the distal end of 
the endoscope or borescope, so only a small fraction of any force applied 
transversely at the proximal end would transfer to the distal end. 
From the foregoing, it will be evident that the eyepiece adapter 10 shown 
in FIGS. 1 through 5 provides a simple, reliable adapter 10 with no moving 
parts. There are no small cavities in which sterilization materials or 
other debris can collect. The adapter 10 centers and aligns its axis 18 
with the optical axis 23 simply and typically with a one-handed operation. 
Moreover, the structure of the clamping member 34, the step 31 and the 
annular wall 34 allow a single adapter to be used with a variety of 
eyepieces of a given diameter irrespective of the configuration of their 
housing. 
FIG. 6 discloses a mechanical coupler that is constructed in accordance 
with this invention and that is an integral portion of an optical device. 
More specifically, FIG. 6 discloses an endoscope 50 with an elongated 
tubular sheath 51 that extends from the proximal end shown in FIG. 6 to a 
distal end (not shown). Typically an endoscope 50 includes a lens housing 
52 at the proximal end of the sheath 51 and a light source 53 coupled to 
the lens housing 52. In this particular embodiment an eyepiece section 54, 
containing eyepiece optics, includes as axially displaced housing 
elements, an eyepiece neck section 55, a flared conoidally-shaped housing 
section 56 and a peripheral flange portion 57 that forms a direct viewing 
port for the endoscope 54. 
A mechanical coupler 60 constructed in accordance with this invention and 
having the same general configuration as shown at the second end section 
20 of FIGS. 1 through 5, includes an end section 61 attached to an optical 
device 62, for example, a television camera. The other end section 63 of 
the mechanical adapter 60 includes a cylindrical wall 64 with an axial 
step portion 65. A clamping plate 66 has a central portion 67 affixed to 
the axial step 65 and free ends 70 that extend essentially tangentially 
from the central portion 67 to form a C-shaped clamping member. The 
cylindrical wall 64 and axial step 65 form a socket 71 with a radially 
extending base 72 for receiving the eyepiece 54. 
The procedures for attaching and separating the optical device 62 to and 
from the endoscope 50 are the same as described with respect to the 
adapter 10 shown in FIGS. 1 through 5. An individual grasps the endoscope 
50 with one hand in the area of the eyepiece 54 and the lens housing 52 
and the optical device 62 with the integral coupler 60 in the other hand. 
Then holding the endoscope 50 in a steady fashion, the adapter 60 is slid 
radially around the eyepiece flange 57. After the flange 57 seats in the 
socket 71, the optical device 62 can be rotated with respect to the 
endoscope 50 until an appropriate orientation in the viewed image is 
obtained. A locking means, such as the locking screw 46 in FIGS. 1 and 2, 
but not shown in FIG. 6, can maintain the appropriate orientation. 
The coupler 60 in FIG. 6 exhibits all the desirable criteria. It is a 
simple integral structure with no moving parts. It is readily sterilized 
without any concerns over the accumulation of sterilizing solutions or 
debris. It is highly reliable and is designed for manufacture at less cost 
than prior art couplers used for the same purposes. It also is simple to 
use. 
It will be apparent that a number of variations can be made to mechanical 
couplers of this invention, particularly the adapter 10 of FIGS. 1 through 
5 and the coupler of FIG. 6 while attaining some or all of the advantages 
of this invention. For example, the step 31 in FIG. 1 extends for 
approximately 180.degree.. It is possible for the extent of that step 31 
to be reduced to less than that complete angle, particularly if no locking 
structure is included. Different fastening devices might be used to affix 
the clamps 34 and 66 to the axial steps 13 and 65 respectively. In FIG. 1 
the eyepiece 13 is formed integrally with the adapter 10. In FIG. 6, the 
coupler 60 is formed integrally with the optical device 62. Alternatively 
the adapter 60 might comprise a threaded mounting structure allowing it to 
be connected to a variety of different optical devices. Different 
applications may permit other materials to be utilized, the materials 
described here being particularly appropriate for use in endoscope 
applications. Thus, while this invention has been disclosed in terms of 
certain embodiments, it is the intent of the appended claims to cover all 
such variations and modifications as come within the true spirit and scope 
of this invention.