BACKGROUND OF THE INVENTION:

This invention relates to optical devices, and particularly to foldable and focusable binoculars.

In recent years, the portability of binoculars has been enhanced by various means of retracting and folding lenses as well as by arrangements for changing the optical paths. However-, this has not resulted in trul -light and inexpensive binoculars which are capable of being focused. Compact focusable binoculars are generally heavy.

An attempt has recently been made .to introduce light binoculars composed of objective and ocular lenses supported in a rigid cardboard frame which, when disassembled, folds into a flat package. However, such binoculars have a fixed focus. Aside from the inconvenience created for the user ^' , the fixed focus places a burden of manufacturing accuracy upon the cutting and folding machinery for the cardboard frame supporting the lens. An inaccurate cut or fold, by the manufacturer or user, could result in a permanently defocused condition which would make the binoculars substantially useless.

SUMMARY OF THE INVENTION:

An object of the invention is to avoid the disadvantages of the aforementioned devices.

Another object of the invention is to provide inexpensive, compact, foldable, and focusable optical devices, such as binoculars.

These objects are attained in whole or in part by connecting ocular and objective lenses with a resilient arrangement

projecting in a direction convex to the space between the lenses so that compression of the resilient arrangement in the direction of the space changes the distance between the lenses.

According to another feature of the invention, movement of the lenses towards each other increases the convexity of the . arrangement and allows the entire binoculars to be folded flat.

According to, another feature of the invention, the alignment of the lenses is maintained by a portion of the arrangement which connects the lenses, but extends in a direction concave to the space between, the lenses.

According to another feature of the invention, two objective and two ocular lenses are provided.

These and other features of the invention are pointed out in. the claims. Other objects and advantages of the invention will become evident from the following detailed description when read in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS:

Fig. 1 is a perspective view of a binocular e obodying features of the invention.

Fig. 2 is a section II-II of the binocular of Fig. 1.

Fig. 3 is a section III-III of the binocular in Fig. 1.

Fig. 4 is a plan view of a single cardboard sheet which is cut and. folded to form the frame of the binocular in Figs. 1 to 3.

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Fig. 5 is an exploded view of a hinge formed in the binocular of Figs. 1 to 3.

Fig. 6 is a perspective view of the connection in Fig. 5 when actually interlocked.

Fig. 7 illustrates the binocular of Figs. 1 to 3 in a folded stowable position.

Fig. 8 is a section similar to III-III of another binocular embodying the invention.

Fig. 9 is a section II-II of the binocular in Figs. 1 to 3 when folded, or collapsed to the condition shown in Fig. 7.

Fig. 10 is a somewhat schematic section III-III of the binocular in Figs. 1 to 3 when transversely compressed to extend the front lenses as far from the rear lenses as possible and thus to produce maximum close-up focus.

Fig. 11 is a somewhat schematic section II-II of the binocular in Figs. 1 to 3 when compressed as in Fig. 10 for maximum close-up.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS:

In Figs. 1 to 3, a single sheet 10 of cardboard cut as shown in Fig. 4 is folded, creased, interlocked, and glued into the shape shown in Figs. 1 to 3. Preferably, the cardboard is of the plastic-coated variety to prevent soiling during use. The sheet is folded to form front and rear walls 12 and 14, a top front panel 16, a rear top panel 18, a bottom front panel 20, a bottom rear panel 22,

a front left panel 24, a rear left panel 26, a front right panel 28, a rear right panel 30, and an overhang panel 32. The overhang panel 32 is fastened by glue to the forward edge of the upper front panel 16. The front wall 12 supports a rectangular plastic optical element 34 which is molded into a flat plate throughout most of its length and into two integral convex lenses 36 and 38 whose front faces 40 and 42 project through suitable openings 44 and 48 in the front wall. Glue or other adhesive fixes element 34 to the front wall 12.

Similarly, the rear wall 14 supports a plastic optical element 50 which is molded-to be substantially flat and rectangular along its length, but integrally forms two concave lenses 52 and 54 aligned respectively with lenses 36 and 38 and with two holes OH in the rear wall 14.

The panels 16 and 18 form a roof-shaped connection between the walls 12 and 14 by virtue of the crease 60 between the panels 16 and 18, and the panels 20 and 22 similarly form an inverse roof-shaped connection between the walls 12 and 14 by virtue of the crease 62 between the latter two panels. The panels 16, 18, 20, and 22 thus form a convex structure relative to the space between, the lens elements 34 and 50. On the other hand, the panels 24, 26, 28, and 30 are bent inwardly so as to form concave structure between the walls 12 and 14. The panels 24 and 26 as well as 28 and 30 each contains a cut 55 and 56 that extends approximately half way into the panel so that the panels can be made to interlock as shown in somewhat exaggerated form in Fig. 6.

By pressing the wall 12 against the wall 14, the user folds the entire binocular into the compact, flat shape shown in Fig. 7 and in Fig. 9.

The binoculars of Figs. 1 to 3 are normally stored, and carried in the folded form shown in Figs. 7 and 9. For convenience, an envelope is provided into which the binocular is slipped. When a user withdraws the binoculars from the envelope, he or she presses with the thumb and fingers in the direction shown by the arrows 57 and 58 to spread the front and rear walls 12 and 14 away from each other so that the structure, takes the shape shown in Figs. 1 to 3. The crease 60 in the cardboard sheet 10 between the panels 16 and 18, as well as the panels 20 and 22 is creased and folded tightly so that the normal storage condition of the structure as shown in- Fig. 7 creates a heavily outward bias to the roof section composed of panels 16 and 18 and the roof section composed of panels 20 and 22. That is, the peak of the upper roof section tends to rise up while the peak of the inverted roof section tends to go down. This gives the user the opportunity to hold the binocular by placing the finger on the panels 16 and 18 with the thumb near the crease 62 between the panels 20 and 22, while holding the binocular with the ocular lenses 52 and 54 near the user's eyes. The user then can squeeze the arrangement between the crease 60 (at the junction of panels 16 and 18) and the crease 62 (at the junction of the panels 20 and 22). The squeezing and releasing changes the distance between the lenses 38 and 54 and between the lenses 36 and 52 so as to change the focusing action of the lenses.

As used herein, the terms objective and front lenses refers to lenses 36 and 38 which are intended to face the object being viewed. The terms ocular and rear lenses refers to the lenses 52 and 54 intended to be placed next to the eyes for ^' iewing.

The panels 24, 26, 28, and 30, when interlocked, maintain an approximately parallel relationship between the walls 12 and 14 during the focusing adjustment. Naturally, the.panels 24 to 30 move

relative to each other during the focusing adjustment, but nevertheless, maintain the relationship. As the binocular is folded from the position shown in Figs. 1 to 3 towards the position in Fig. 7 by pressing the front wall 12 toward the rear wall 14-, the panels 24 to 30 fold inwardly until the panel 24 lies against the panel 26 and. the panel 28 lies against the panel 30 and all the panels lie between the lens elements 34 and 50. The panels 24 to 30 thereby prevent the lenses 36 and 42 from contacting the lenses 52 and 54 and. thereby inhibit scratching of the lenses by the other lenses.

In manufacture, the cardboard sheet 10 shown in Fig. 4 is cut from a blank with the holes 44 and 48 for the lenses 36 and 38 and holes OH for the lenses 52.and 54. .The manufacturing process further involves, although not necessarily in. the order indicated, creasing the cut blank sheet 10 at lines 60, 62, 64, 66, 68, 70, 72, 74, 76, and 78, with a press or the like, gluing the bottom of the flap 16 to the top of the flap 32, interlocking the panels 24 to 30, gluing the lens elements 34 and 50 to the walls .12 and 14, and folding the binocular to the shape shown in Fig. 7. Preferably, the folds are such as to maintain the outward resilience of the creases (or folds) 60 and 62. In this- way, as the user squeezes the binoculars between the folds 60 and 62, the binoculars continue to exhibit an outward bias that allows the user to hold the binoculars as he or she presses and releases the panels at the folds 60 and 62 for the purpose of focusing. The distances are related to the focal lengths of the lenses 36, 38, 52, and 54 so that the binoculars are focused upon the most close-up position when the creases 60 and 62 are squeezed virtually flat, and focused upon- infinity when the panels 16, 18, 20, and 22 are released into a roof-like position convex relative to the space, between the lenses. When the binoculars are squeezed so that the panels 16 and 18 at the crease 60 and the panels 20 and 22 at the crease 62 are substantially flat from wall 12

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to wall 14, the side panels 24, 26, 28 ^' , and 30 are also substantially flat. According to one embodiment of the invention, the cuts 55 and 56 in the panels 24 to 30 are sufficiently far from the walls 10 and 12 so that the panels 16-22 project slightly inward toward the space between the lenses when the creases 60 and 62 at the panels 16 to 20 have been pressed flat by forces in the direction of arrows 57, 58. This prevents the panels 16 to 20 from being pressed into the space between the elements 34 and 50. It maintains the resilience of the creases that bias the panels 16 to 22 outwardly of the space between the lens elements 34 and 50.

The flap 32 and the portion to which it is glued on the flap 16 form a sun shade for light entering the lenses 36 and 38. These flaps 32 and 16, when the binoculars are folded into the carrying shape shown in Fig. 7, also cover the lenses 36 and 38 and prevent their scratching. However, because the -binoculars, when folded flat, are normally stored in an envelope, such protection may not be necessary. For this reason, according to an embodiment of the invention, the overlap may occur at the crease 60 as shown in Fig. 8 or at the crease 62.

Fig. 9 shows the binocular of Figs. 1 to 3 folded as in Fig. 7 by pressing wall 12 toward wall 14. It is similar to Fig. 7 in that it illustrates a section, but the section is horizontal rather than vertical as in Fig. 7. The panels 24 to 30 are folded completely in the now narrow space between the elements 34 and 50 which are shown only schematically.

Figs. 10 and 11 are vertical and horizontal sections of the binoculars in Figs. 1 to 3, and correspond respectively to Figs. 3 and 2, but show the binocular with the panels 16 and 18 as well as 20 and 22 compressed at creases 60 and 62 by finger pressure so that the

panels 16 and 18 are flat and the panels 20 and 22 are flat between the walls 12 and 14. Similarly, the panels 24 and 26 are flat and the panels 28 and 30 are substantially flat between the walls 12 and 14. In this portion the lens elements 34 and 50 are as far as possible from each other and in their maximum close-up position of focus.

While embodiments of the invention have been described in detail, it will be 'evident to those skilled in the art that the invention may be embodied otherwise without departing from its. spirit and scope.

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