Optical waveguides – Accessories – Plug/termination device
Reexamination Certificate
2002-05-28
2004-04-06
Zarroli, Michael C. (Department: 2839)
Optical waveguides
Accessories
Plug/termination device
C385S088000
Reexamination Certificate
active
06718113
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a conversion plug for an optical or light signal configured such that it can be plugged in directly an optical signal input terminal or optical signal output terminal mounted on one of various types of audio visual apparatuses or devices, personal computers, etc., and a method of fabricating the conversion plug, and more particularly, to a conversion plug for an optical or light signal comprising a plug portion adapted to be plugged in directly the optical signal input or output terminal and a plug-in hole for an optical plug that cannot be plugged in directly the optical signal input or output terminal, and capable of optically coupling between the optical plug inserted into the plug-in hole and the optical signal input or output terminal with low optical loss, and a method of fabricating such conversion plug.
2. Description of the Related Art
In recent years, with the advance of optoelectronics, there have been provided many kinds of audio visual apparatuses such as a DVD (Digital Versatile Disk) player/recorder, MD (Mini-Disk) player/recorder, CD (Compact Disk) player/recorder and the like, and electronic apparatuses or devices such as personal computers and the like, each being provided with an optical input terminal and/or optical output terminal for an optical or light digital signal (hereinafter, referred to as optical signal terminal). In an optical signal terminal is directly plugged one of two optical plugs mounted to an optical cable (for example, optical fiber) at opposed ends thereof respectively, that transmits an optical or light digital signal, thereby to transmit an optical digital signal from the optical signal terminal to the optical cable or from the optical cable to the optical signal terminal.
In Japan, there have been generally used as optical connectors for a digital audio signal an optical plug having its plug portion of 3.5 mm in outside diameter and an optical signal terminal (optical receptacle or jack) configured such that an optical plug of this size can be plugged in, and an optical plug having its plug portion of 2.5 mm in outside diameter and an optical signal terminal (optical receptacle or jack) configured such that an optical plug of this size can be plugged in. In addition, there are two types of optical plugs one being called a round or circular shape optical plug and the other being called a square or quadrilateral shape optical plug from the external appearances of their plug portions. The round shape optical plug can be plugged in only an optical signal terminal having its structure corresponding to that optical plug, and likewise, the square shape optical plug can be plugged in only an optical signal terminal having its structure corresponding to that optical plug. Though a square shape optical plug is configured that its core, namely, optical fiber projecting therefrom has a rod-like shape that is circular in section, a wall member of polygonal or square shape in section is coaxially formed about the core, and hence it will be called a square or quadrilateral shape plug.
As a result, it is impossible to plug a round shape optical plug having its plug portion of 3.5 mm in outside diameter in an optical signal terminal configured such that a round shape optical plug having its plug portion of 2.5 mm in outside diameter, for example, can be plugged in, and it is also impossible to plug a round shape optical plug having its plug portion of 2.5 mm in outside diameter in an optical signal terminal configured such that a round shape optical plug having its plug portion of 3.5 mm in outside diameter can be plugged in. The same is true in case of square shape optical plugs. In addition, even if two optical plugs have their plug portions of the same outside diameter, it is impossible to plug a round shape optical plug in an optical signal terminal configured such that a square shape optical plug can be plugged in, and it is also impossible to plug a square shape optical plug in an optical signal terminal configured such that a round shape optical plug can be plugged in.
For the reason described above, as is disclosed in Japanese Patent Application Public Disclosure No. hei 5-88043 (88043/1993), for example, there has been proposed an optical adapter that is capable of connecting two optical plugs having their plug portions of different outside diameters with each other. This optical adapter comprises a cylindrical adapter housing and an optical fiber of a predetermined length aligned on the central axis of the adapter housing, and optically couples, through the optical fiber aligned on the central axis of the adapter housing, between two optical plugs having their plug portions of different outside diameters plugged in the adapter housing from the opposed end portions thereof, respectively. If such type of optical adapter is used, it is possible to optically connect, for example, between a round shape optical plug having its plug portion of 3.5 mm in outside diameter and a round shape optical plug having its plug portion of 2.5 mm in outside diameter, between a round shape optical plug having its plug portion of 3.5 mm in outside diameter and a square shape optical plug having its plug portion of 2.5 mm in outside diameter, between a square shape optical plug having its plug portion of 3.5 mm in outside diameter and a round shape optical plug having its plug portion of 2.5 mm in outside diameter, or between a square shape optical plug having its plug portion of 3.5 mm in outside diameter and a square shape optical plug having its plug portion of 2.5 mm in outside diameter, with each other.
As described above, an optical plug is mounted to each end of an optical cable (an optical fiber is typically used as an optical cable, and hence it will be referred to as optical fiber, hereinafter), and one plug of the optical fiber is plugged in an optical signal terminal mounted on one of electronic apparatuses or devices or the like and the other plug thereof is plugged in the optical adapter. Since two optical plugs are inserted into the optical adapter, an optical coupling is effected between the optical fiber of the one optical plug inserted thereinto and the optical fiber provided in the optical adapter and between the optical fiber of the other optical plug inserted thereinto and the optical fiber provided in the optical adapter. In this manner, optical couplings inevitably occur twice in the optical adapter of such type, and hence there is an serious disadvantage that optical loss is increased. Moreover, two optical fibers are optically connected in series with each other through the optical adapter, and if the two optical fibers have the same length, the total length of the two optical fibers becomes twice the length of one optical fiber. It is preferred that the length of an optical fiber is as short as possible for the reason of optical transmission characteristic thereof.
For the aforesaid reasons, there has been earnestly desired in this technical field a conversion plug for an optical signal adapted to optically couple an optical plug that cannot be plugged in directly a desired optical signal terminal to this desired optical signal terminal with low optical loss and without lengthening the total length of the optical fiber.
In the technical field of electrical connectors, there has been put to practical use as disclosed in, for example, Japanese Utility Model Application Publication No. hei 1-29751 (29751/1989) an adapter-plug adapted to be capable of electrically connecting an electric plug that cannot be plugged in directly a receptacle or jack mounted on one of audio visual apparatuses or devices, and electronic apparatuses or devices such as personal computers and the like because the plug portion thereof has a different outside diameter, to that receptacle or jack. Such adapter-plug for an electrical signal is constructed such that it electrically connects an electric plug inserted into the adapter-plug with the adapter-plug with each other by use of
Mine Keiji
Nakagawa Hiroshi
Hosiden Corporation
Lathrop, Esq. David N.
Zarroli Michael C.
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