Optical: systems and elements – Lens – With support
Reexamination Certificate
2000-05-24
2001-10-30
Epps, Georgia (Department: 2873)
Optical: systems and elements
Lens
With support
C359S830000
Reexamination Certificate
active
06310735
ABSTRACT:
BACKGROUND
The invention relates to a releasable and stress-free securing assembly for an optical element positioned in a centered manner in a mount. The optical element is provided, in the border region which is to be retained, with a beveled surface inclined in the direction of the mount. The mount has a groove which is open axially in front of the optical element, and a ring element which is elastically deformable in the axial direction is pressed in between the beveled surface and groove.
A securing assembly of this type is known from German Publication DE 29 22 287 A1. A lens positioned in a centered manner in a mount body is retained by an elastic ring, running in the vicinity of the circumference, under elastic prestressing against an axial abutment of the mount body. The ring consists of a rubber-like elastic material and is pressed into a ring groove of the mount body. The ring groove is partially overlapped in the axial direction by the circumferential surface of the lens. The cross section of the ring groove is intended to be at least of the same size as that of the ring, and it is to be possible for the lens to be inserted even if the ring has been placed in position beforehand. Possible shapes specified for the ring groove are rectangular, semicircular and trapezoidal cross sections, that is to say, shapes which enclose the ring in an essentially convex manner.
German Publication DE 1 113 101 PS also discloses such a securing assembly in which the ring groove corresponds precisely to the cross section of the pressed-in ring. On the mount body, it is intended to arrange, above the ring groove, an inwardly oriented, obliquely positioned peripheral surface which may be interrupted in the form of bayonet-like lugs.
Although these securing assemblies have already been known for decades, they have not gained widespread acceptance in practice.
A securing assembly which is comparable as far as outlay for, and processing of, parts are concerned involves the optical element being secured by a snap ring engaging in a groove in the mount. The snap ring usually consists of metal and may be of a circular or rectangular cross section. The depth of the groove and the snap-in depth of the snap ring in the radial direction are coordinated with one another. The height of the lens border and the position of the adjacent groove likewise have to be adapted to one another with great precision in order that the lens fit is neither too loose nor too tight. It is only possible to compensate for tolerances by way of costly follow-up work. It is not possible to compensate for dimensional tolerances produced by temperature fluctuations. Removal of the snap ring without scratching the lens surface is only possible if extreme care is taken. However, in particular in the case of optical systems made up of a number of elements, subsequent removal is necessary if particles of dirt are found in the system following assembly.
It is known, from German Utility Model 1 966 392, to provide above the lens, positioned in a centered manner, in the mount body a conically shaped groove into which there is inserted a plastic snap ring which has a correspondingly shaped conical facet. The conical abutment surface produces a contact-pressure force which acts in the axial direction, counteracts loosening of the snap ring and compensates for production tolerances in the groove. Since the snap ring consists of plastic, the risk of the lens surface being scratched is avoided.
It is also the case that this type of securing assembly has not been able to gain widespread acceptance.
SUMMARY OF THE INVENTION
An object of the invention was for the securing assembly known per se to be developed, by optimizing the variables which significantly influence a firm hold for the optical elements, such that they can also be used, in particular, for mounts of high-performance optical systems.
This object is achieved according to the invention, in the case of a securing assembly of the type mentioned in the introduction, in that the angle of inclination of the beveled surface is between 40° and 50°, in that that boundary of the groove which is located in the region of the optical element is level with the bevel edge which is oriented toward the mount, and that boundary of the groove which is located in front of the optical element is undercut at an angle of from 10° to 15°, in that the depth of the groove is greater than the radius of the ring element by 0.15 to 0.2 mm, and the free opening between that bevel edge which is located on the optical element and the front edge of the undercut boundary of the groove is equal to 0.8 of the diameter of the ring element.
For the introduction of the ring element, it is advantageous if the front edge of the undercut boundary of the groove is rounded. The Shore hardness of the ring element should preferably be approximately 70.
The ring element provided may also be a radial annular spring, of which the ring elements can be indented by the bevel edge which is located on the optical element. The annular spring may also be designed such that its spring force, by suitable inclination of the ring elements, acts between the beveled surface and the undercut boundary of the groove.
The basic idea of the invention is to form, merely between the beveled lens border and the groove, a cavity into which the elastically deformable ring element can be pressed. The specified dimensions prevent the situation where the ring element can spring out of the cavity and, on the other hand, also the situation where the ring element cannot be pushed fully out of the retaining position into the cavity beyond the lens border. The deformability in the axial direction allows tolerance compensation between the inner bevel edge and undercut boundary of the groove, as well as compensation for material deformation in the axial direction. The bevel edge which is located on the lens surface indents the pressed-in ring element and, in addition, prevents the ring element from springing out automatically. The undercut of the groove boundary which is located opposite said bevel edge serves for securing the pressed-in ring element further against springing out automatically.
In addition, sealing of the mount can be achieved by using a closed O-ring as the ring element, it being possible, on account of the Shore hardness selected, for the O-ring, on the one hand, to be sufficiently elastic and, on the other hand, still to be punctured, and drawn out, by a needle-like tool. This virtually completely rules out damage to the lens surface.
Annular springs are known and, as far as design and properties are concerned, are described in a catalog GDM3M, sheet 9, from Bal Seal of Amsterdam, Holland. The entire contents of this catalog are incorporated herein by reference. They are available in the form of radial annular springs and as axial annular springs. U.S. Pat. No. 5,052,782 describes the use of an axial annular spring in conjunction with a lock ring for securing lens elements in a stress-free manner. In the case of axial annular springs, the ring elements are inclined in relation to one another, with the result that they may be inclined further, under spring stressing, under the pressure of the lock ring. In the case of the radial annular spring provided according to the invention, the ring elements are indented on the bevel edge which is located on the lens element and, moreover, are locked in the opposite undercut.
REFERENCES:
patent: 5052782 (1991-10-01), Myer
patent: 1 113 101 (1963-05-01), None
patent: 1 966 392 (1967-08-01), None
patent: 29 22 287 (1980-12-01), None
patent: 200113391-A (2001-01-01), None
Best Stefan Uwe
Schnabel Rainer
Epps Georgia
Foley & Lardner
Leica Camera AG
Seyrafi Saeed
LandOfFree
Releasable and stress-free securing assembly for optical... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Releasable and stress-free securing assembly for optical..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Releasable and stress-free securing assembly for optical... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2589148