Optical: systems and elements – Compound lens system – Telescope
Reexamination Certificate
2000-04-24
2001-03-27
Spyrou, Cassandra (Department: 2872)
Optical: systems and elements
Compound lens system
Telescope
C359S428000, C033S277000
Reexamination Certificate
active
06208461
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an arms sight and, more particularly, to an optical arms sight usable for daytime operations and for nighttime operations and provided with means for protection of an image intensifier used in the night-vision aiming system.
DESCRIPTION OF THE PRIOR ART
In general a sight is utilized for aiming a gun at a directly visible target. In order to aim a gun, some form of a sighting device is required. There is a variety of sights used in weapons, and one of them is known as an optical sight. For shooting with high accuracy, each specific sight has to be adjusted to each specific rifle, and after being once removed, the adjustment procedure has to be repeated again. The sighting device may move with the gun barrel or may be separated from the gun. In general the use of such sighting devices in guns is well known.
In general, light conditions can be roughly classified into the following three categories: daylight, dusk, and nighttime. Therefore, the existing optical gun sights can be roughly classified as optical gun sights specifically for daytime shooting, for nighttime shooting, and for both light conditions. It is understood that the first two specialized sights give adequate high-accuracy performance but are not interchangeable without repeated rifle adjustment. Therefore, the users of such guns normally have two rifles for use under different light conditions. For intermediate light condition, such as dusk, depending on the amount of light, the shooter can use either a nighttime or a daytime sight. In the case shooting in the dusk is carried out with the use of a rifle equipped with the daytime optical sight, to make the reticle visible on the background, the sight is typically provided with a device for illuminating a targeting mark on a reticle. Such reticle illumination system is disclosed, e.g., in U.S. Pat. No. 4,806,007 issued in 1989 to G. Bindon.
As far as the universal sights for both nighttime and daytime use is concerned, they usually utilize either two optical paths, one for daytime conditions and another for nighttime conditions with switching between both, or replaceable ocular units, one for daytime conditions and another for nighttime conditions. Those universal sights which incorporate two optical paths, are more complex in design and lack compactness. A single-path universal optical gun sight is disclosed in U.S. Pat. No. 4,822,994 issued in 1989 to C. Johnson, et al. This gun sight, which is adapted for shooting at any time of the day, is normally provided with both a reticle illuminating device and replaceable ocular units which can be removably attached to a preadjusted optical gun sight on a rifle.
It understood that for nighttime shooting an optical sight should be equipped with a special light-intensifying device. Such a device is commonly known as an “intensifying tube” or “image intensifier”. More specifically, the function of an image intensifier is to multiply the amount of incident light received by it to produce a greater signal for application to the eyes of a viewer. As such, these devices have been employed by the military and in commercial devices as well. Examples of early uses of such devices can be made by reference to a text entitled “Photoelectricity and Its Applications” published in 1949 by John Wiley & Sons. Chapter 18 entitled “Light Beam Signalling and Infrared Detection” shows examples of early nighttime vision devices which may be employed as gun sights such as the Sniperscope and Snooperscope.
The aforementioned image intensifiers are capable of increasing the intensity of incoming light in the optical sight up to 60,000 times and lately to 90,000. The image intensifier is a very complicated and expensive device which contributes up to 70% of the cost of the entire gun sight. It is also understood that the image intensifier amplifies by a factor of 60,000 or 90,000 not only the light reflected from the target and the surrounding objects, but also the light which is scattered by a targeting mark on the reticle illuminated by the aforementioned reticle illumination device, such as light-emitting diode. Although optical gun sights of the aforementioned type have a mechanism for adjusting the level of reticle illumination by incorporating multiple-position rotary switches, used, i.e., in gun sights of Aries 6600 model produced by American Technology Networks, South San Francisco, Calif., nothing prevents such sights from accidentally being left in the position corresponding to the reticle illumination level sufficient for “burning” the intensifier. In other words, if one accidentally forgets to switch the dusk reticle illumination device off, the expensive image intensifier tube can be irrecoverably damaged. This, in turn, will demand that the entire nighttime unit be replaced.
U.S. Pat. No. 5,272,514 issued in 1993 to Dor discloses a modular day
ight weapon aiming system which comprises a red dot aiming portion having a light emitting diode, a combining mirror, and an apparatus for mounting the LED and the mirror on a weapon to produce a virtual image of the LED at an infinite distance in alignment with the bore sight of the weapon. The device also includes a removable night vision portion having an objective lens, an eyepiece, and an image intensification tube for intensifying a received image intermediate the objective lens and the eyepiece, wherein the virtual image is visible to the operator at night through the eyepiece, and the night vision portion is removed for use of the red dot aiming portion during the day. Generally, the system disclosed in the U.S. Pat. No. 5,272,514 possesses the same disadvantages as the previously described systems, in other words, it does not provide the protection of the image intensifier tube from being accidentally burned by the light produced by the LED or other light sources.
SUMMARY OF THE INVENTION
The optical gun sight for daytime and nighttime use in which a reticle illumination system has two operation states, one with full range of illumination for shooting during daytime and dusk and the other with the range of illumination safe for the expensive image intensifier tube. When the optical arms sight is used under night vision conditions, switching means interlocked with the nighttime aiming unit automatically switches off the reticle illumination system so that the expensive image intensifier tube is protected from accidental damage due to “burning” of the reticle. In another embodiment the reticle-illumination circuit is not switched off completely but rather is switched over to the level of light or a wavelength of light safe for the image-intensifier tube, e.g., to infrared light.
OBJECTS OF THE INVENTION
It is an object of the invention to provide an optical gun sight equipped with a reticle illumination device which allows safe switching between the daytime and nighttime modes of operation without a risk of damaging an expensive image intensifier.
Another object of the invention is to provide an optical gun sight device capable of automatically switching the daytime reticle illumination system off when a nighttime aiming system is installed.
Another object of the invention is to provide the gun sight of the aforementioned type which is simple and compact in construction.
Still another object of the invention is to provide the system of the night vision eyepiece protection compatible with the gun sights of various optical design, such as those utilizing both reflective and transmission optics.
REFERENCES:
patent: 4806007 (1989-02-01), Bindon
patent: 4822994 (1989-04-01), Johnson et al.
patent: 5272514 (1993-12-01), Dor
patent: 5283427 (1994-02-01), Phillips et al.
patent: 5745287 (1998-04-01), Sauter
American Technologies Network
Robinson Mark A.
Spyrou Cassandra
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