Brushing – scrubbing – and general cleaning – Implements – Fabric
Reexamination Certificate
2002-03-28
2004-11-02
Chin, Randall (Department: 1744)
Brushing, scrubbing, and general cleaning
Implements
Fabric
C015S104001, C015S104040, C015S209100
Reexamination Certificate
active
06810552
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a cleaning tool for an optical connector which cleans an optical connector for connecting optical fibers.
As optical communication or optical measurement using light has developed remarkably in recent years, the loss at the connecting portion of an optical connector for connecting optical fibers poses a problem.
In such an optical connector, optical fibers are generally connected to oppose each other. In this case, if the connecting end face of the optical connector is soiled or a substance such as fats and oils or dust attaches to it, the insertion loss of the optical fiber is increased to decrease the reflection attenuation amount, and an optical signal cannot be transmitted correctly. For this reason, the connecting end face of the optical connector must be cleaned periodically or when necessary to remove the soil or attaching substance.
Conventionally, when the connecting end faces of optical connectors are to be cleaned, the operator cleans the end faces by wiping them with a cleaning tool, e.g., a cleaning sheet or paper impregnated with ethyl alcohol, or spraying nitrogen gas to them. In the wiping cleaning operation using a cleaning sheet or paper impregnated with alcohol, the amount of alcohol to be used and the wiping degree change depending on the operator who performs cleaning, and the cleaning effect tends to vary. Since alcohol tends to catch fire easily, it must be handled and stored with sufficient care.
In view of this, a dry cleaning tool has recently been proposed to replace the wet cleaning tool described above. According to the dry cleaning tool, a cleaning cloth formed into a tape-like shape is urged and rubbed against a ferrule end face (connecting end face), thereby removing an attaching substance, e.g., a soil, dust, or oils and fats, attaching to the ferrule end face, particularly the coupling surface (end face) of an optical fiber which forms one plane together with the connecting end face.
FIGS. 9 and 10
show a dry cleaning tool for an optical connector previously filed by the present applicant. This cleaning tool
1
has a thin box-like case
2
, and the structure shown in
FIG. 10
is loaded in the case
2
. This structure has a supply pulley
4
on which a tape-like cleaning sheet
3
is wound, a take-up pulley
5
for taking up the cleaning sheet
3
, and a ratchet mechanism (not shown) for rotating the supply pulley
4
in only a predetermined direction (take-up direction) to prevent the cleaning sheet
3
from becoming loose.
Part of one side wall
2
a
along the long side of the case
2
has an open window
6
for exposing the cleaning sheet
3
to the outside, and a shutter
7
for opening/closing the open window
6
. A rotary drive mechanism (not shown) for driving the supply pulley
4
, a tape feed grip
8
for driving the rotary drive mechanism, and a pad
9
for receiving and supporting that sheet portion of the cleaning sheet
3
which is exposed from the open window
6
are built in the case
2
.
FIG. 11
shows an example of an optical connector
10
to be cleaned by the cleaning tool
1
shown in
FIGS. 9 and 10
. This optical connector
10
has a plug body
11
and a ferrule
12
built in the plug body
11
and with a front end face (connecting end face) projecting from the front end face of the plug body
11
. An optical fiber
13
is arranged at the center of the ferrule
12
. While the optical fiber
13
is inserted in the ferrule
12
, it is fixed with an adhesive or the like such that its coupling surface
13
a
as the distal end face forms one plane together with the connecting end face of the ferrule
12
. In this state, the connecting end face of the ferrule
12
and the coupling surface
13
a
of the optical fiber
13
are mirror-surface polished.
When optical connectors
10
with this structure are employed, the coupling surfaces
13
a
of the optical fibers
13
are brought into contact with each other by engagement of an engaging portion
14
formed on the side surface of one plug body
11
and an engaging portion formed on the plug body of the mating optical connector. Hence, the plug bodies
11
are coupled to each other and an optical signal is transmitted. In this case, if the coupling surfaces
13
a
are soiled, or a substance such as dust or oils and fats attaches to them, light from the optical fiber
13
is absorbed to increase the insertion loss of the optical connectors
10
, thereby decreasing the reflection attenuation amount. Consequently, the optical signal cannot be transmitted correctly.
When the connecting end face of the ferrule
12
in the optical connector
10
and the coupling surface
13
a
of the optical fiber
13
are to be cleaned by the cleaning tool
1
, first, the user grips the tape feed grip
8
. Then, the shutter
7
opens interlocked with the tape feed grip
8
, to expose the cleaning sheet
3
to the outside from the open window
6
. Also, the rotary drive mechanism (not shown) is driven to rotate the take-up pulley
5
in the take-up direction. Therefore, the supply pulley
4
feeds a predetermined amount of cleaning sheet
3
, so that a new, unused sheet portion is supplied to the open window
6
. In this state, when the connecting end face of the ferrule
12
of the optical connector
10
is urged and rubbed against the surface of the cleaning sheet
3
exposed from the open window
6
, the substance such as a soil, dust, or oils and fats attaching to the coupling surface
13
a
of the optical fiber
13
is removed, thus cleaning the coupling surface
13
a
. After cleaning, when the user releases the holding state of the tape feed grip
8
, the tape feed grip
8
is restored to the initial position by the force of a spring incorporated in the case
2
, and the shutter
7
closes the open window
6
.
With the conventional cleaning tool
1
described above, although the connecting end face of the ferrule
12
and the coupling surface
13
a
of the optical fiber
13
can be cleaned well by removing the attaching substance or soil from them, the side surface of the ferrule
12
cannot be cleaned at all. If a substance such as dust attaches to the side surface of the ferrule
12
, or the optical connector
10
in a soiled state is mounted in a device or the like, the insertion loss is increased due to the attaching substance or soil on the side surface of the ferrule
12
, and the reflection attenuation amount decreases. As a result, an optical signal cannot be transmitted correctly.
This will be described in more detail by means of a practical example. As shown in
FIGS. 12
or
13
, when sebum, dust, or a polishing liquid (containing diamond abrasive grains, SiO
2
crystals, alumina, or the like) attaches to the side surface of the ferrule
12
, the optical fibers
13
to be connected are not connected such that their coupling surfaces do not oppose each other correctly, but the optical axes of the two optical fibers are tilted. Then, as shown in
FIG. 14
, the insertion loss increases in accordance with the degree of the tilt of the optical axes. This insertion loss is correlated not only to the tilt (angular shift) of the optical axes but also to the offset (misalignment) and gap. When an angular shift of 1° occurs, off-axis occurs simultaneously. Therefore, the insertion loss is the sum of the angular shift and misalignment. With dust or the like attaching to the side surface of the ferrule, when this ferrule is to be connected with another ferrule, if an angular shift occurs between the two ferrules, this leads to a very large influence. For example, with a misalignment of 0.5 mm, the connection loss becomes 0.1 dB. Generally, a connection loss at one connection point must be 0.2 dB or less. If misalignment occurs, as described above, an angular shift also occurs, and the connection loss at this time becomes 0.1 dB. Therefore, the sum of the connection loss becomes 0.2 dB, which is larger than the general requirement. Referring to
FIGS. 12 and 13
, reference numeral
1
denotes a split sleeve;
2
, an adapter sleeve holder
Fukuhara Ai
Goto Hitoshi
Miyake Taisei
Nara Kiyoshi
Sawa Kazuya
Blakely & Sokoloff, Taylor & Zafman
Chin Randall
NTT Advanced Technology Corporation
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