Optical: systems and elements – Compound lens system – Telescope
Reexamination Certificate
1998-11-19
2001-02-13
Henry, Jon (Department: 2872)
Optical: systems and elements
Compound lens system
Telescope
C359S399000, C359S434000, C359S407000
Reexamination Certificate
active
06188516
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an observing unit incorporating a telescopic optical system having a wide view and a bright field of view and, in particular, to a monocular or binoculars having a reverse reflection type of optical system between an objective lens system and an eye lens system.
BACKGROUND OF THE INVENTION
In watching sports, such as soccer or rugby, which are played in a large playground by players who move quickly, or in watching a play in a theater having a laterally extending stage, it is desirable to use a monocular or binoculars having a wide view.
As to an observing unit incorporating a telescopic optical system to be used for these purposes, a type of binoculars called “opera glasses” has been widely used. Opera glasses are formed of the Galileo optical system, as known in the art, which uses a convergent lens as an objective lens and a divergent lens as an eye lens. The Galileo optical system advantageously allows opera glasses to be small in size and lightweight to be used conveniently, but results in opera glasses having a relatively narrow view, a dark field of view, and a low power.
On the other hand, a high-power observing unit incorporating a telescopic optical system includes a reverse reflection optical system, which is composed of two or three prisms placed between an objective lens and an eye lens. The overall optical system of such an observing unit is complicated. Thus, although this type of an observing unit may have a power of up to seven magnifications, its actual view tends to be narrow, for example, less than 10 degrees. Accordingly, this type of observing unit has not been adequate for observing an object that moves quickly.
In an observing unit incorporating a telescopic optical system, such as binoculars having a high power, a reverse reflection optical system has been the hindrance to obtain a wide view. Accordingly, the overall design of a telescopic optical system itself has been the key to obtaining a wide view. As a result, the arrangement of a telescopic optical system has become complicated, greatly increasing the weight, size, and cost of the observing unit that incorporates such a telescopic optical system, and further negatively affecting its portability and manipulatability.
In general, although an antinomic condition that the higher the power, the narrower the view cannot be avoided in principle, it is known in the art that using an objective lens having a minimum focal distance is preferable in obtaining a wide view. On the other hand, if a reverse reflection optical system composed of two or three prisms is incorporated in an image-erecting optical system, an objective lens should have a focal distance that takes into consideration the optical path length of these prisms. Accordingly, the overall optical system becomes bulky in proportion to the size of the prisms. This makes it difficult to form compact and, thus, portable observing units. Further, the size of a reverse reflection optical system comprising a couple of prisms determines the size of an objective lens to be used.
A need exists for a compact monocular or binoculars having a wide view, a bright field of view, and a high power.
SUMMARY OF THE INVENTION
The present invention provides an arrangement in which a reverse reflection optical system is interposed between an objective lens system and an eye lens system. The reverse reflection optical system includes a first reflector arranged at an angle of 45 degrees to an incident optical axis. The reverse reflection optical system also includes a right-angled isosceles triangle prism having roof surfaces whose ridge line is laid on an axis parallel with the incident optical axis so as to receive reflected light from the first reflector at a part of an oblique side surface of the prism. The reverse reflection optical system also includes a second reflector arranged to face another part of the oblique side surface of the prism so as to be at an angle of 45 degrees with respect to a reflecting optical axis of the light reflected from the prism. A relay lens is arranged between the objective lens system and the eye lens system adjacent the second reflector of the reverse reflection optical system.
In one aspect of the present invention, in order to effectively attain the object of the present invention, a meniscus lens is used as the relay lens arranged between the objective lens system and the eye lens system. The convex surface of the meniscus lens is arranged so as to face an incident side. A portion of the meniscus lens is located within a projection area projected by the second reflector on a horizontal plane that includes the incident optical axis.
With this arrangement, it is possible to provide a monocular or binoculars having a wide view and a bright field of view, while maintaining a high power.
REFERENCES:
patent: 715793 (1902-12-01), Harvey
patent: 788823 (1905-05-01), Dieckmann
patent: 5684635 (1997-11-01), Sugawara
patent: 5812324 (1998-09-01), Fukumoto
patent: 11633 (1914-04-01), None
patent: 847316 (1960-09-01), None
Christensen O'Connor Johnson & Kindness PLLC
Henry Jon
Kamakura Koki Kabushiki Kaisha
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