Television – Special applications – With endoscope
Reexamination Certificate
1997-12-30
2001-01-30
Britton, Howard (Department: 2713)
Television
Special applications
With endoscope
C348S068000, C433S029000, C600S182000
Reexamination Certificate
active
06181369
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a videoscope employing an image sensor such as a charge coupled device (CCD), and especially relates to a dental scope used for a dental or oral use.
Recently, such a videoscope has been used for an examination or a medical care of an oral cavity in a dental clinic or in oral surgery. One type of such videoscope employs an optical fiber for guiding light rays as disclosed in Japanese laid open patent applications (Tokukaihei) 4-176436 and 4-285525, for example. Another type disclosed in Japanese laid open patent application (Tokukaisho) 62-246347 uses an optical fiber for guiding an image of the object to the image sensor such as CCD. The videoscope disclosed in Tokukaihei 4-176436 uses an optical system including lenses for guiding an image of the object to the image sensor.
Such a videoscope is required to be easy to handle with one hand, have a high quality image and an inexpensive price for wide use.
The prior art disclosed in Tokukaihei 4-176436 has an optical fiber for guiding light rays. This optical fiber should have a complicated shape fitting to a narrow space inside the videoscope, which also contains lenses and prisms for condensing or dispersing light rays. However, since an optical fiber is hard to bend in a small angle and is easy to break, it can hardly extend to the tip inner portion. It is also difficult to decrease the number of the components.
The videoscope of the prior art has another disadvantage in that it is not easy to handle since it has an optical fiber connecting a grip portion of the videoscope and an external light source box, in addition to an electric cable connecting the grip portion of the videoscope and an external video circuit. The optical fiber and the electric cable can be integrated into a cord in recent technology, but it is not enough to improve the difficulty in handling the videoscope.
Moreover, the videoscope of the prior art needs a long optical path including lenses or an optical fiber for transmitting a light image of the object to an image sensor. This complicated structure makes it difficult to reduce the size and cost of the video scope.
The present invention is aimed at a novel structure of such a videoscope that enables easiness of handling and an inexpensive price.
SUMMARY OF THE INVENTION
A videoscope of the present invention comprises a grip portion at a proximal end to be held by an operator; an insert portion at a distal end to enter the oral cavity or other objects; a light window formed in the wall of the insert portion for illuminating an object; an acceptance window formed in the wall of the insert portion for receiving reflected light from the object; an image sensor disposed in the tip of the insert portion for receiving the light from the object to generate an electric signal corresponding to the object image; a light emitting member disposed in the grip portion; and a light guide for guiding light rays from the light emitting member to the light window. The light guide has a condensing portion that condenses the light rays emitted by the light emitting member, a guiding portion in which the light rays can propagate by total reflection, and a shedding portion that sheds the propagated light rays through the light window.
According to the above mentioned structure, since the image sensor is disposed in the tip of the insert portion, it can receive the light rays containing the image of the object directly without an optical fiber or other optical guide members. Light rays for illuminating the object are guided by the light guide from the light emitting member in the grip portion to the light window in the tip of the insert portion. The structure of the present invention is simpler and lower in cost than that of the prior art. It enables the videoscope to be compact and easy to handle since it does not need an optical fiber extending to the outside of the videoscope.
It is preferable that the videoscope has a plurality of light windows formed in the wall of the insert portion for illuminating an object, the light emitting member includes a light source and a concave mirror that reflects the light rays from the light source in the direction toward the tip of the insert portion, and the light guide has a plurality of shedding portions, a plurality of guiding portions and a condensing portion that condenses the light rays from the light source and the concave mirror to the plurality of guiding portions.
It is also preferable that the videoscope further comprises a video circuit disposed in the grip portion and a mirror disposed between the video circuit and the light emitting member for reflecting the light rays from the light emitting member in the direction toward the tip of the insert portion. The mirror in this structure works not only for condensing the light rays but also as a heat shield for the video circuit when the light has a certain heat that may damage the video circuit.
It is also preferable that the cross section of the insert portion has a substantially oblong profile, and the light window and the acceptance window are formed in the wider side wall of the insert portion.
It is also preferable that the light guide has a recess for receiving a light source such as a lamp, and the condensing portion is formed around the recess. In this structure, the condensing portion of the light guide preferably includes a mirror portion that reflects and condenses light rays from the light source to the direction of the guiding portion. Such a mirror portion can be formed by a metal film evaporated on the surface of the light guide or a reflecting sheet stuck on the surface of the light guide.
It is also preferable that the cross section of the condensing portion of the light guide has a substantially oblong profile, and the mirror portion has different curvatures between the longitudinal direction and its perpendicular direction of the oblong cross section.
It is also preferable that a part of the surface of the condensing portion, which does not satisfy the angular condition for the total reflection of the light rays, has a second mirror portion. This mirror portion also can be formed by a metal film evaporated on the surface of the light guide or a reflecting sheet stuck on the surface of the light guide. The second mirror portion preferably has a zigzag inner surface for reflecting the light rays from the light source back to the light source or the periphery of the light source. The zigzag inner surface preferably has flat faces perpendicular to the direction toward the light source.
It is also preferable that the recess for receiving the light source is formed in the direction perpendicular to the longitudinal axis of the light guide. This structure facilitates setting or replacing of the light source such as a lamp from the side of the light guide.
It is preferable that the light source is a lamp with a filament, the cross section of the guiding portion of the light guide has a substantially oblong profile, and the lamp is set in its position such that the longitudinal direction of the filament is along the longitudinal direction of the cross section profile of the guiding portion. This structure enables an efficient usage of the light from the light source.
It is preferable that the shedding portion of the light guide has an oblique shedding face for illuminating the object efficiently. Alternatively, the shedding portion of the light guide has a shedding face with small prisms that diffuse the light rays for illuminating the object uniformly and mildly.
It is also preferable that the side wall of the insert portion is transparent or semitransparent at least partially, and light rays leaked from the light source or the light guide illuminate the object indirectly through the transparent or semitransparent part of the insert portion.
The present invention may be applied to the videoscope that further comprises an optical fiber for guiding light rays from an external light source box to the light emitting member in the grip portion of the videoscope. In thi
Atsuta Hiroshi
Ooshima Kiyoko
Uchida Shinji
Yamakita Hiroyuki
Britton Howard
Matsushita Electric - Industrial Co., Ltd.
Merchant & Gould P.C.
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