Visual aid device having a locking device

An eyeglass frame supports a pair of mounting adapters. Each mounting adapter includes a connecting mechanism for removably connecting an optical device. The connecting mechanism permits the optical device to be inserted with a low insertion force, but requires a relatively large force for removing the optical device. The connecting mechanism includes an interior bore that accepts an insertion shank on the optical device. A series of Teflon balls are placed in radial channels in an outer wall of the mounting adapter. An O-ring in a groove in the outer wall urges the Teflon balls into the radial channels. The radial channels are shaped to prevent the Teflon balls from falling into the insertion bore, but allow the Teflon balls to protrude partly into the insertion bore. The insertion shank of the optical device has a bevel that forces the Teflon balls out of its path as it is inserted into the interior bore. At a point during insertion, the Teflon balls fall into a second groove behind the bevel, temporarily locking the optical device in place.

BACKGROUND OF THE INVENTION 
The present invention relates generally to optical devices and specifically 
to wearable visual aids. 
The performer of fine, detailed work, such as surgery or watchmaking, is 
helped by visual aid devices that reduce eye fatigue and increase visual 
acuity. One such visual aid device is disclosed in U.S. Pat. No. 4,834,525 
issued May 30, 1989 to Vansaghi. Referring to FIG. 1, a visual aid device 
10 features telescopes 121, 123 mounted on eyeglass frames 111 via carrier 
lenses 117, 119. Carrier lenses 117, 119 may be prescription lenses to 
provide visual correction to permit a visually impaired user to see 
through the portions of carrier lenses 117, 119 peripheral to the areas 
covered by telescopes 121, 123. Since carrier lenses 117, 119 may be 
prescription lenses, visual correction is provided for such peripheral 
viewing. In addition, referring also to FIG. 2, corrective lenses 137 may 
be affixed to bushings 127 to provide visual correction during viewing 
through telescopes 121, 123. 
Visual aid device 10 may be designed specifically for a particular user to 
accommodate his anatomical and visual correction needs. However, the ideal 
optical characteristics of such devices depend on the particular task as 
well as on the particular user. For example, a cardiovascular surgeon may 
require telescopes having different optical characteristics than required 
by a dentist. Such optical characteristics include the focusing or working 
distance, the distance from the user's eyes to the region being observed, 
and the magnification factor. Moreover, the same specialist might require 
telescopes with different optical characteristics for different tasks, 
such as a dentist who performs both chair-side surgery and laboratory 
bench work. Such customization may require that separate devices be 
purchased for each user or task. Such multiple purchases involve 
considerable expense, especially when carrier lenses 117, 119 and 
corrective lenses 137 are manufactured especially for a particular user. 
To solve this problem, visual aid device 10 has been designed with 
interchangeable telescopes. Telescopes 121, 123 are removably mounted on 
respective carrier bushings 125, 127 by means of bayonet-type mounts. The 
bayonet-type mount includes a front portion 131 of bushing 127, which is a 
female member that receivably mates with a male member 139 at an end of 
telescope 123. An interior bore 141 of bushing 127 has a circumferential 
groove 143 for receiving mating tabs 145 of male member 139. An outer wall 
132, which bounds circumferential groove 143, has slots 152 to permit 
mating tab 145 to enter circumferential groove 143. Telescope 123 is 
pushed toward bushing 127 as male member 139 is inserted in interior bore 
141 until mating tabs 145 pass through slots 152. Telescope 123 is then 
rotated 1/8th of a turn to slide mating tabs 145 in circumferential groove 
143 and lock behind solid portions 153 of outer wall 132. A detente 
mechanism (not shown) locks mating tabs 145 in position so that telescope 
123 cannot thereafter be rotated easily. Thus, telescope 123 cannot fall 
out. 
Though the prior-art device of FIGS. 1 and 2 permits lenses to be 
interchanged, positive locking of the lens may not be achieved. If 
telescope 123 is rotated insufficiently to engage the detente device, 
telescope 123 will stay in place for a time, but it will not be positively 
locked in place. If not locked in place, telescope 123 can fall out of 
interior bore 141 during use. If telescope 123 should fall out during 
surgery or some other delicate work, great hardship could result. 
In addition to making it possible for telescope 123 to fall out of place 
during use, the bayonet-type mount requires telescope 123 to be 
rotationally as well as axially aligned with the bushing, inserted and 
then twisted, which is inconvenient. 
Another problem with the prior art visual aids is the difficulty of 
compensating for axial misalignment of telescopes 121, 123. Telescopes 
invariably incorporate some axial misalignment due to manufacturing 
tolerances causing the line of sight of the telescope to be different from 
that for which the mount is ideally configured. Such misalignment can 
result in poor imaging and/or eye fatigue. 
Still another problem with the prior art device is that no means is 
provided for changing the force required to insert and rotate mountings 
such as the bayonet mount of the prior art. This may present a difficulty 
for users who prefer easier and faster changing telescopes 121, 123. 
OBJECTS AND SUMMARY OF THE INVENTION 
It is an object of the present invention to overcome the drawbacks of the 
prior art. 
It is another object of the invention to provide a wearable visual aid 
device that permits the use of interchangeable optical devices. 
It is still another object of the present invention to provide a 
through-the-lens mounting mechanism for interchangeable optical devices 
for wearable visual aid devices. 
It is still another object of the present invention to provide a 
through-the-lens mounting mechanism for interchangeable optical devices 
for wearable visual aid devices that prevents accidental disengagement of 
an interchangeable optical device. 
It is still another object of the present invention to provide an afocal 
telescope which becomes a complete telescope with selectable focusing 
distance upon attachment of an insert lens. 
Briefly stated, the invention provides an eyeglass frame that supports a 
pair of mounting adapters. Each mounting adapter includes a connecting 
mechanism for removably connecting an optical device. The connecting 
mechanism permits the optical device to be inserted with a low insertion 
force, but requires a relatively large force for removing the optical 
device. The connecting mechanism includes an interior bore that accepts an 
insertion shank on the optical device. A series of Teflon balls are placed 
in radial channels in an outer wall of the mounting adapter. An O-ring in 
a groove in the outer wall urges the Teflon balls into the radial 
channels. The radial channels are shaped to prevent the Teflon balls from 
falling into the insertion bore, but allow the Teflon balls to protrude 
partly into the insertion bore. The insertion shank of the optical device 
has a bevel that forces the Teflon balls out of its path as it is inserted 
into the interior bore. At a point during insertion, the Teflon balls fall 
into a second groove behind the bevel, temporarily locking the optical 
device in place. 
According to an embodiment of the present invention, there is disclosed, a 
visual aid, comprising: a wearable frame for holding an optical device 
near a wearer's eye, a mounting adapter, having an opening, fixedly 
connected to the frame, an optical device having an insertion shank at an 
end thereof, the insertion shank being insertable in the mounting adapter, 
means for engaging the insertion shank upon application of a first force 
in a first direction to the insertion shank while the insertion shank is 
inserted in the opening, the means for engaging including means for 
disengaging the insertion shank upon application of .a second force to the 
insertion shank while the insertion shank is inserted in the opening and 
the second force being greater in magnitude than, and opposite in 
direction to, the first force. 
According to another embodiment of the present invention, there is 
disclosed, a visual aid, comprising: a spectacle frame, a carrier lens 
fixedly mounted in the spectacle frame, a mounting adapter fixedly 
attached to the carrier lens, the mounting adapter having an interior 
bore, an annular outer wall and a center axis, at least one engaging 
member movably connected to the mounting adapter, means for urging the 
engaging member partly into the interior bore, an optical device having an 
insertion shank, the insertion shank being insertable into the interior 
bore and the insertion shank having an annular edge for engaging the 
engaging member when the insertion shank is inserted in the interior bore. 
According to still another embodiment of the present invention, there is 
disclosed, a visual aid, comprising: a wearable frame, an afocal 
telescope, a main lens in the afocal telescope, an insert lens attachable 
to the afocal telescope, a mounting adapter attached to the wearable 
frame, the mounting adapter having means for attaching a corrective lens 
on the mounting adapter, the afocal telescope being incapable of bringing 
a subject into focus for a normally-sighted user of the visual aid and the 
afocal telescope with the insert lens attached being capable of bringing 
the subject into focus for the normally-sighted user of the visual aid. 
According to still another embodiment of the present invention, there is 
disclosed, a visual aid, comprising: a wearable frame, an afocal 
telescope, a main lens in the afocal telescope, an insert lens attachable 
to the afocal telescope, a mounting adapter attached to the wearable 
frame, the mounting adapter having means for attaching a corrective lens 
on the mounting adapter, the mounting adapter having an opening, the 
afocal telescope being incapable of bringing a subject into focus for a 
normally-sighted user of the visual aid, the afocal telescope with the 
insert lens attached being capable of bringing the subject into focus for 
the normally-sighted user of the visual aid, the afocal telescope having 
an insertion shank at an end thereof, the insertion shank being insertable 
in the opening in the mounting adapter, means for engaging the insertion 
shank upon application of a first force in a first direction to the 
insertion shank while the insertion shank is inserted in the opening, the 
means for engaging including means for disengaging the insertion shank 
upon application of a second force to the insertion shank while the 
insertion shank is inserted in the opening and the second force being 
greater in magnitude than, and opposite in direction to, the first force. 
According to still another embodiment of the present invention, there is 
disclosed, a visual aid comprising: a mounting adapter, means for 
supporting the mounting adapter in a line of sight of a user, an optical 
device, means for permitting attachment of the optical device in the 
mounting adapter, and for removing the optical device from the mounting 
adapter, the means for permitting including means for locking the optical 
device in a locking position in the mounting adapter when the optical 
device is fully attached in the mounting adapter and the means for 
permitting attachment including means for requiring a greater force to 
remove the optical device from the locking position than for attaching the 
optical device in the locking position. 
According to still another embodiment of the present invention, there is 
disclosed, a telescope comprising: an afocal telescope, an insert lens 
assembly mountable on the afocal telescope, the insert lens assembly 
having a focal length effective, together with the afocal telescope, to 
permit production of an image at a selectable distance and a corrective 
lens having a shape effective to correct for a visual impairment of a 
user. 
According to still another embodiment of the present invention, there is 
disclosed, a visual aid, comprising: a wearable frame, a mounting adapter 
affixed to the wearable frame, a telescope, the mounting adapter including 
means for rotatably connecting the telescope to the mounting adapter, the 
means for rotatably connecting including means for permitting removal of 
the telescope from the mounting adapter. 
The above, and other objects, features and advantages of the present 
invention will become apparent from the following description read in 
conjunction with the accompanying drawings, in which like reference 
numerals designate the same elements.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIG. 3, a visual aid device 9 includes a frame 11 with temple 
pieces 13 and a nose bridge 15. Carrier lenses 17, 19 are held in frame 
11. Each of carrier lenses 17, 19 has a respective one of a pair of 
mounting adapters 25, 27. Each of mounting adapters 25, 27 holds one of a 
pair of optical devices such as telescopes 21, 23. 
Carrier lenses 17, 19 may be made of plastic or ground glass and may be 
shaped to correct for visual impairment. In the embodiment shown in FIG. 
3, carrier lenses 17, 19 are bifocal corrective lenses. In another 
embodiment, not shown, carrier lenses have an optically neutral shape, for 
users who do not require correction. 
Frame 11 and carrier lenses 17, 19 are preferably made of heat and chemical 
resistant materials to allow them to be sterilized when telescopes 21, 23 
are removed. A preferred material for frame 11 is powder coated aluminum 
which is heat tolerant, light-weight and has a non-oxidizing surface. The 
non-oxidizing powder-coated surface would not contribute to particulate 
contamination of clean environments such as surgical theaters and 
manufacturing clean rooms. 
In preferred embodiment, frame 11 is provided with means for changing 
carrier lenses 17, 19. The ability to change carrier lenses 17, 19 permits 
a user to install carrier lenses 17, 19 in a new frame 11 if frame 11 
should be damaged. This may save the cost of new carrier lenses 17, 19 and 
mounting adapters 25, 27. Also, it is preferred for 
Mounting adapters 25, 27 are permanently mounted in respective apertures 
(not shown) in carrier lenses 17, 19. Angles of mounting of mounting 
adapters 25, 27 determine respective viewing angles through telescopes 21, 
23. These angles should be established so that lines of view converge at 
the focusing distance of the telescopes 21, 23 mounted in mounting 
adapters 25, 27. Determining the best angles for mounting mounting 
adapters 25, 27 is a skill known in the art. This skill is explained in 
U.S. Pat. No. 4,834,525 issued May 30, 1989 to Vansaghi and U.S. Pat. No. 
3.273,456 issued Sep. 20, 1966 to Feinbloom, the disclosures of which are 
incorporated herein by reference. 
Referring now to FIG. 4, an afocal telescope 33 is insertable into mounting 
adapter 27. Afocal telescope 33 has an insertion shank 34 that fits 
loosely into an interior bore 35 of mounting adapter 27. Insertion shank 
34 has a profile 36 shaped to form an annular groove 43 and an annular 
bevel 44. One of a variety of different insert lenses 31 with threads 31a 
can be screwed into afocal telescope 23 to provide telescope 23 with a 
selectable focusing distance. 
Referring now also to FIG. 5, mounting adapter 27 has an annular O-ring 
groove 46, which holds an O-ring 42. O-ring 42 is made of resilient 
material and is held under tension in O-ring groove 46. Beneath O-ring 42 
are balls 41, which are held under compression under O-ring 42. Balls 41 
fit into radial ball channels 47 in mounting adapter 27. Balls 41 are urge 
toward, and partly into, interior bore 35 by O-ring 42. Ball openings 55 
allow balls 41 to protrude slightly into interior bore 35. Balls 41 are 
preferably made of a self-lubricating material such as Nylon or Teflon. 
The number of balls 41 may be chosen as required for stability and easy 
use. According to the preferred embodiment described herein, the preferred 
number of balls 41 is six. 
Referring now to FIG. 6, as insertion shank 34 is inserted in interior bore 
35, balls 41 ride easily up annular bevel 44, thereby stretching O-ring 
42. When annular groove 43 is moved close enough to balls 41, balls 41 are 
urged into annular groove 43. As balls 41 move into annular groove 43, a 
positive force is applied to insertion shank 34 urging insertion shank 34 
into interior bore 35. Annular groove bevels 56, at outer edges of annular 
groove 43, allow balls 41 to slide into annular groove 43 smoothly. In 
addition, annular groove bevels 56 allow insertion shank 34 to be removed 
by allowing balls 41 to ride up annular groove bevels 56 when insertion 
shank 34 is removed from interior bore 35. Thus, as full insertion of 
insertion shank 34 is approached and then reached, balls 41 snap into 
annular groove 43 providing an audible click and tactile feedback to the 
user. 
As clearly shown in FIG. 6. annular groove bevel 56 is substantially 
steeper than annular bevel 44. The shallowness of annular bevel 44 permits 
insertion shank 34 to be inserted into interior bore 35 with a relatively 
low force. By contrast, the steepness of annular groove bevel 56 makes it 
necessary to apply a relatively great force to insertion shank 34 to 
remove insertion shank 34 from interior bore 35. The effect of the 
steepness of annular groove bevel 56 and the shallowness of annular bevel 
44 is that optical fittings, such as telescope 23, require less force to 
insert into mounting adapter 27 than to remove therefrom. Thus telescope 
23 cannot fall out of mounting adapter 27 while visual aid device 9 is in 
use. 
The audible and tactile feedback provided by the snapping of balls 41 into 
annular groove 43 is particularly important to a user who has extremely 
poor sight. A user who relies on visual aid device 9 for correction of a 
profound visual defect, may be unable to see well enough with visual aid 9 
removed to change telescopes 21, 23 easily. The audible and tactile 
feedback is an important feature for such a user. 
If insertion shank 34 is inserted only partly into interior bore 35, the 
force exerted by balls 41 against annular bevel 44 tends to urge insertion 
shank 34 out of mounting adapter 27. Thus, in addition to making it easier 
to install optical devices into mounting adapters 25, 27, the mechanism of 
mounting adapter 27 and insertion shank 34 clearly shows any failure to 
obtain positive engagement between insertion shank 34 and mounting adapter 
27. This is because if positive engagement is not established, the 
incomplete engagement permits insertion shank 34 to slip easily out of 
mounting adapter 27. 
The design of mounting adapter 27 and insertion shank 34 permits telescope 
23 to rotated freely while inserted in mounting adapter 27. This permits a 
rotational position of telescope 23 to be changed while the telescope is 
being used. This is useful because telescopes 21, 23 invariably 
incorporate some axial misalignment causing the lines of sight of 
telescopes 21, 23 to be different from the alignment for which the 
positions of mounting adapters 25, 27 are best suited. The effect of the 
axial misalignment can be reduced or eliminated by rotating telescopes 21, 
23. For the same reason, different users may have anatomical eye positions 
which make it difficult for them to see through symmetrically arranged 
telescopes 21, 23. Independently rotating the slightly off-axis telescopes 
21, 23 also makes it possible to compensate for this such anatomical 
asymmetry of the user. 
Alternative methods of urging balls 41 into interior bore 35 may be 
employed. For example, a metal or plastic compression ring could be used 
place of O-ring 41. It is preferable, according to a feature of the 
present invention, for the means for urging balls 41 into interior bore 35 
to permit balls 41 to be removed or installed. O-ring 41 has been found to 
be ideal for this purpose. Changing the number of balls 41 provides the 
user the ability to select the insertion force of insertion shank 34. 
Reducing the number of balls 41 reduces the insertion force and firmness 
of the attachment between mounting adapter 27 and insertion shank 27. 
Increasing the number of balls 41 increases the insertion force and 
firmness of the attachment between mounting adapter 27 and insertion shank 
27. 
A corrective lens 51 is fixedly mounted in posterior bore 81 of mounting 
adapter 27. This provides visual correction during viewing through 
telescope 23. Corrective lens 51 may also be used to provide protection 
from ultra-violet light, radiation and laser light through the use of 
various known optical coatings and treatments. Because corrective lens 51 
remains in place when telescope 23 is removed, such protection is still 
provided with telescope 23 removed. Note, also, that lens 51 may be a 
plano lens when visual correction is not required by the user and such a 
plano lens may provide the same protection to the user. 
Referring now also to FIG. 7, a diameter C' of a posterior bore 81 of 
mounting adapter 27 is smaller than a diameter B' of interior bore 35, 
creating a step 53 between them. Front portion 52 of insertion shank 34 
has a diameter C which fits snugly in posterior bore 81 when insertion 
shank 34 is fully inserted into mounting adapter 34. Profile 36 has a 
diameter B which fits snugly in interior bore 35 when insertion shank 34 
is fully inserted into mounting adapter 27. Thus, precise alignment is 
achieved when insertion shank 34 is fully inserted in mounting adapter 27. 
But because front portion 52 is substantially smaller than interior bore 
35, insertion shank 34 is easy to align with interior bore 35 for 
insertion of insertion shank 34 into interior bore 35. This simplifies the 
changing of telescopes 23. 
Afocal telescope 33 requires insert lens 31, which is threadably secured to 
afocal telescope 33, to become operable telescope 23. This is because an 
insert lens element 73 is essential for telescope 23 to form an image. In 
addition, by changing insert lens 31, a focusing distance of telescope 23 
may be changed without changing the entire telescope 23. 
According to one embodiment of the present invention, afocal telescope 33 
contains a concave element 71 and convex main lens 72 to form an afocal 
portion of a Galilean telescope which is completed with the attachment of 
insert lens 31. Insert lens 31 contains a single insert lens element 73 
that determines, within a specified range, the focusing distance of 
telescope 23. Corrective lens 51 remains attached to mounting adapter 27 
frame 11 as do corrective carrier lenses 17, 19, so that all elements 
specific to the user are attached to frame 11. All other elements, afocal 
telescope 33 and insert lens 31, are interchangeable. 
According to another embodiment (not shown) afocal telescope 33 includes 
reflective or refractive elements to increase a light path and thereby 
accommodate a main lens 72 with a longer focal length. By increasing the 
focal length of main lens 72, the magnification of the resulting telescope 
23 can be increased. For example, a reflective element such as a roof 
prism may be used in afocal telescope 33 forming a Capellarian telescope, 
once insert lens 31 is attached. As in the other embodiments, the focusing 
distance of the Capellarian telescope can be changed by changing insert 
lens 31. 
Changing insert lens 31 changes the optical characteristics of telescope 
23. By permitting the changing of insert lens 31, the invention allows a 
single afocal telescope to serve in a range of applications. For example, 
if the user needs to change the distance at which telescopes 21, 23 focus, 
the user can obtain additional insert lenses 31 instead of obtaining an 
entire telescopes 21, 23. If greater change in optical characteristics is 
required than can be effected by changing insert lens 31, afocal telescope 
33 can be changed without changing frame 11, carrier lenses 17, 19, or 
mounting adapters 25, 27. Interchangeable insert lens 31 and telescope 23, 
25 permit a range of optical characteristics to be enjoyed by the user 
with the purchase of a minimum of costly elements. In addition, customized 
elements, such as corrective lens 51 and carrier lenses 17, 19, are 
permanently attached to frame 11. The other components, telescopes 21, 23, 
and insert lens 31, can be used by different users and interchanged at 
will. This interchangeability permits a group of users to share, for a 
relatively low cost, a supply of devices that have a range of optical 
characteristics. 
According to the embodiments of the invention described, a visual aid 
device may include a pair of telescopes 21, 23. It is possible to 
incorporate some or all of the features of the invention in an embodiment 
having only one telescope. In addition, according to the embodiments 
described, mounting adapter 27 is fixedly secured to carrier lenses 17, 
19. However, it is possible to incorporate some or all of the features of 
the present invention in other embodiments having other means for 
supporting mounting adapter 27 in a line of sight of a user. For example, 
a frame connected directly to mounting adapter 27 could be employed. 
Having described preferred embodiments of the invention with reference to 
the accompanying drawings, it is to be understood that the invention is 
not limited to those precise embodiments, and that various changes and 
modifications may be effected therein by one skilled in the art without 
departing from the scope or spirit of the invention as defined in the 
appended claims.