1986-10-22
1989-02-07
Zazworsky, John
350 9624, G02B 104, G02B 600
Patent
active
048027227
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to an optical cable adapted to be used in reading an optical information carrier, the cable containing a light conductor for transferring light from the information carrier to a light-sensitive receiver.
BACKGROUND
Light conductors have different properties with relation to flexibility, light divergence angle, and reception angle depending on what material they are made from. These angles are equally as great for a given light conductor and represent the angle within which the light can be spread from, or collected by, the end of the light conductor. A plastic optical fibre is relatively pliant and generally has a comparatively large light divergence angle. Fibres having a comparatively small light divergence angle are usually manufactured from glass or quartz. However, such fibres are not as pliant as plastic fibres and, furthermore, they are more easily damaged by bending. As an example of the magnitude of the light divergence and light reception angle, it may be stated that in a plastic fibre this is usually between 45.degree. and 90.degree., while the corresponding angle for a glass or quartz fibre is usually only about 15.degree. to 40.degree..
In the G.B. specification No. 1,375,963 there is described an optical cable intended for use in reading an optical information carrier. The cable contains a plurality of fibre conductors, of which the majority are utilized for illuminating the information carrier, and one is utilized for transmitting the light reflected from the carrier to a light-sensitive receiver.
If the information carrier is a display screen, no further illumination thereof is necessary, and thus no fibres are required which lead light to it. Irrespective of how the information carrier is illuminated, however, it is desirable that the so-called reading fibre, i.e. the fibre which transmits light from the information carrier to the light-sensitive receiver, have a small light reception angle. Good resolution is obtained in such a case, which is important for reading information such as bar codes.
SUMMARY OF INVENTION
An object of the present invention is to provide an optical cable which is easy to bend, while at the same time being characterized by being able to take up light from an information carrier within a comparatively small angle.
In achieving the above and other objects and advantages of the invention, there is provided an optical cable adapted for use in reading an optical information carrier. This cable comprises a light conductor adapted for transmitting light from the information carrier to a light-sensitive receiver, the light conductor including a major portion of an easily bendable material, there being furthermore provided an end portion facing away from the light sensitive receiver and comprising a separate light conductor, the light reception angle of which is less than the corresponding angle of the said major portion for obtaining good resolution. According to a particular embodiment, the major portion is of a plastic material and the end portion is of glass or quartz. Preferably, the light reception angle of the end portion is about 15.degree. to 40.degree. and the corresponding angle of the aforesaid major portion is about 45.degree.-90.degree..
The above and other objects, features and advantages of the invention will be found in the Detailed Description of the invention which follows hereinbelow.
The invention will next be described in detail with reference to the accompanying drawing, in which:
FIG. 1 is a side elevational view of an optical cable; provided in accordance with the invention;
FIG. 2 is an end elevational view of the light conductors in an optical cable comprising several light conductors; and
FIG. 3 is a side elevational view of certain of the light conductors in the cable according to FIG. 2.
DETAILED DESCRIPTION
A side elevation of an optical cable is shown in FIG. 1. The cable is intended for use in reading from an information carrier such as a display screen and comprises a light conductor d
REFERENCES:
patent: 3010357 (1961-11-01), Hirschowitz
patent: 3740113 (1973-06-01), Cass
patent: 3942866 (1976-03-01), Roman
patent: 3995934 (1976-12-01), Nath
patent: 4354734 (1982-10-01), Nakahashi
patent: 4398790 (1983-08-01), Righini et al.
patent: 4483585 (1984-11-01), Takami
patent: 4588294 (1986-05-01), Siegmund
Telefonaktiebolaget L M Ericsson
Zazworsky John
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