United States Patent [19]
[11]
[45]
Fukahori et al.
[54] MULTI-PORT FIBEROPTIC ROTARY JOINT
rotative member, a speed change gear mechanism for
transmitting the rotation of the rotative member to the
Morinaga, Takahagi, all of Japan
[73] Assignee: Hitachi Cable Limited, Tokyo, Japan
[21] Appl. No.: 241,536
Sep. 7, 1988
[22] Filed:
Int.
Cl.4
..............................................
.. G02B 6/36
[51]
[52] US. Cl. ............................... .. 350/96.2; 350/9618
[53] Field of Search ............... .. 350/96.15, 96.18, 96.2,
trapezoid prism so as to rotate the trapezoid prism at an
angular velocity half the angular velocity of the rotative
member, rhomboid prisms provided on the entrance
side of the trapezoid prism so as to optically guide the
light coming from a region outside an aperture of the
trapezoid prism to the trapezoid prism as the light paral
lel to the axis of the trapezoid prism within the aperture
thereof, and the rhomboid prisms provided on the exit
side of the trapezoid prism so as to optically guide the
light emanating from the trapezoid prism to a region
outside the aperture of the trapezoid prism, a plurality
350/9621, 445
References Cited
U.S. PATENT DOCUMENTS
3,350,156 10/1967 Adams
of pairs of convergent lenses respectively provided to
350/445
4,671,613
6/1987
Buhrer ....... ..
4,725,116
2/1988
Spencer et a1. .................. .. 350/962
the rotative member and the fixed member, the conver
.. 350/9618
gent lenses of each pair optically facing each other via
the rhomboid prisms, the trapezoid prism and the rhom
FOREIGN PATENT DOCUMENTS
0111390
boid prisms, and entrance and exit side optical ?bers
6/1984 European Pat. Off. ....... .. 350/9615
respectively connected to the entrance and exit surface
Primary Examiner-John D. Lee
Assistant Examiner—John Ngo
Attorney, Agent, or Firm—Dykema Gossett
[57]
4,872,737
Oct. 10, 1989
zoid prism provided between a rotative member and a
?xed member of the rotary joint so as to be rotatable
relative to the rotative member and coaxial with said
[75] Inventors: Toshio Fukahori; Hideyuki
Takashima, both of Hitachi; Hitoshi
[56]
Patent Number:
Date of Patent:
side convergent lenses.
ABSTRACT
A multi-port ?beroptic rotary joint comprising a trape
50 Claims, 4 Drawing Sheets
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US. Patent
Sheet 1 0f 4
Oct.10,1989
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PRIOR ART
4,872,737 *
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PRIOR ART
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US. Patent
Oct. 10, 1989
6.0
4,872,737
Sheet 2 0f 4
CONVERGENT LENSES
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DISTANCE BETWEEN CONVERGENT LENSESIL(mm)
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US. Patent 0ct.10,1989
FIG .5
Sheet 3 of4
4,872,737
US. Patent
Oct. 10,1989
Sheet 4 of4
4,872,737
1'00
.
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36 34 35
1
4,872,737
2
that of the rotator 2 and transmitting the decelerated
MULTI-PORT FIBEROPTIC ROTARY JOINT
rotation to the prism holder 4. The multi-port ?beroptic
rotary joint is further adapted to couple the light from
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a multi-port ?beroptic ro
the emission side to the receiving side by means of a
tary joint for optically coupling through a trapezoid
prism a plurality of optical ?bers mounted on a rotative
member and a ?xed member of the rotary joint.
2. Background Art
The prior art will be described below with reference
to the accompanying drawings wherein the like refer
ence numerals designate identical elements in different
Figures.
10
connector mechanism (a receptacle 18 and a plug 15)
for connecting the emission optical ?ber 5 with the
optical ?ber 8 and of another connector mechanism (a
receptacle 19 and a plug 46) for connecting the receiv
ing optical ?ber 14 with the optical ?ber 10.
The trapezoid prism 3 forms an inverted mirror
image between an incident light image and an emergent
light image with respect to an optical axis as illustrated
in FIG. 1 when the length of the trapezoied prism 3, l,
satis?es, assuming its aperture to be S, a relation
FIG. 1 illustrates a prior multi-port ?beroptic rotary
l=4.23><S (BK-7, borosilicate glass, is employed as
joint disclosed in Japanese Utility Model Application
Laid Open No. 61-6818 (6818/1986). As illustrated in
prism material). The outer diameters of the optical con
FIG. 1, inside a ?xed member 1 there are provided a
to 10 mm, and hence in a four-core optical rotary joint
for example, the aperture 51:15 to 20 mm and the
length 11:63.5 to 84.6 mm.
However, as illustrated in FIG. 3, coupling loss be
tween the optical ?bers is remarkably increased as the
distance between the convergent lenses goes beyond 50
mm. With 11 being between 63.5 mm and 84.6 mm, the
coupling loss is increased to 3dB to 7dB. In addition,
rotative member 2, a trapezoid prism (dove prism) 3,
and a prism holder 4 rotatable relative to and coaxial
with the rotative member 2. Emission side optical ?bers
5a and 5b are coupled with the entrance surface of the
trapezoid prism 3 through ferrules 6a and 6b, and rod
shaped collimating convergent lenses 9a and 9b, both
mounted on the ?xed member 1. Reception side optical
?bers 14a and 14b are coupled with the exit surface 30 of
the trapezoid prism 3 through ferrules 13a and 13b, and
collimating convergent lenses 10a and 10b, both
mounted on the rotative member 2. Speed change gears
40, 41, 42, and a speed change gear shaft 43 are disposed
among the rotator 2, the prism holder 4, and the ?xed
member 1, which serve in combination as a speed
nectors (receptacles 15, 16, etc.) typically range from 6
slight angular mismatching between the plugs 20a, 20b
and the receptacles 15a, 15b causes a bundle of light to
be expanded at the entrance surface 30, bottom surface
3b, and exit surface 30 of the trapezoid prism 3 thereby
deteriorating the rotation chracteristics of the multi
port rotary joint. In particular, the longer the length of
the trapezoid prism 3, l, the more conspicuous the ex
pansion of the bundle of light due to the angular mis
35 matching. It is accordingly desirable to reduce the
it t'o the prism holder 4.
prism length l to the utmost.
Light from the emission side optical ?ber 5a is colli
change gear mechanism for reducing the angular veloc
ity of the rotative member 2 to half and for transmitting
mated through the convergent lens 9a, allowed to enter
the entrance surface 3a of the trapezoid prism 3, re
fracted therefand entirely reflected at the bottom sur
face 3b of the prism 3. And further, it is refracted at the
exit surface 3c, permitted to go out thereof, collimated
through the convergent lens 10b, and permitted to enter
the receiving side optical ?ber 14b. Another emission
side optical ?ber 5b and the receiving side optical ?ber
140 are also coupled with each other in the same fashion
discribed above. In the optical rotary joint, as the rota
tor 2 rotates, the trapezoid prism 3 rotates at an angular
velocity which is half of that of the rotator 2 in the same
direction, thereby optically cancelling the rotation of
the rotator 2. Hence, couplings between the entrance
and exit side optical ?bers 5a and 14b, and between the
entrance and exit side optical ?bers 5b and 14a are not
deteriorated.
FIG. 2 illustrates another prior example of a multi
port rotary joint as disclosed in Japanese Utility Model
Application No. 60-157843 (157843/ 1985). In the multi
port ?beroptic rotary joint of FIG. 2, an improvement
To solve the aforementioned problem, a measure was
taken as illustrated in FIG. 2, in which intermediate
optical ?bers 8 and 11 are interposed between the recep
tacles 18, 19 and the trapezoid prism 3 in order to im
prove the packaging density of the device. This how
ever results in severe loss of the light when the interme
diate optical ?bers 8 and 11 are bent to an extreme, and
requires a certain length because of the possibility of
their being broken. For this, the total length L1 of the
rotary joint must be large although the length l; of the
trapezoid prism 3 is reduced, making dif?cult their
connection to a rotary part. Furthermore, the interme
diate optical ?bers 8 and 10 terminate at ferrules for
connectors, whose ends therefore needs polishing, caus
ing an increase in fabrication cost as well as an increase
in the coupling loss because of the increase of connec
tions by a factor of two.
SUMMARY OF THE INVENTION
To solve the problem of the prior art discussed above,
it is an object of the present invention to provide a
of the one illustrated in FIG. 1, there are provided
multi-port ?beroptic rotary joint capable of improving
intermediate optical ?bers 8. and convergent lenses 9
between the emission side optical ?bers 5 and a trape
zoid prism 3, and likewise in the rotator 2 side there are
the aforementioned coupling loss as well as the rotation
provided intermediate optical ?bers 11 and convergent
lenses 10 between the receiving side optical ?bers 14
and the trapezoid prism 3. Speed change gears 23, 24, 25
chracteristics of a rotary joint by reducing the prism
length.
Another object of the present invention is to provide
a multi-port ?beroptic rotary joint capable of reducing
not only the prism length but also the entire length of
and 26, and a gear shaft 27 are provided among the 65 the rotary joint.
_
rotator 2, the prism holder 4 and the ?xed member 1 in
the same manner as in FIG. 1 as the speed change gear
provide a multi-port ?beroptic joint capable of being
mechanism for reducing the angular velocity to half of
inexpensively fabricated with ease.
Still another object of the present invention is to
3
4,872,737
Yet another object of the present invention is to pro
4
trance side optical ?bers respectively connected in the
vide a multi-port ?beroptic rotary joint capable of
same number with the rotative member and the ?xed
avoiding the increase in the coupling loss due to mois
ture condensation by preventing the formation of dew
on a prism in an optical rotary joint.
To achieve the above objects, a multi-port ?beroptic
member, a plurality of rhomboid prisms, each provided
for each optical ?ber, namely located between the en
rotary joint according to the present invention com
trance side optical ?bers and the entrance surface of the
trapezoid prism and between the exit side optical ?bers
and the exit surface of the trapezoid prism so as to re
prises a trapezoid prism provided between a rotative
?ect twice if necessary the light from the entrance side
member and a ?xed member so as to be rotatable and
optical ?bers so that the light may propagate through
the aperture of the trapezoid prism in the axial direction
of the trapezoid prism, and a plurality of pairs of con
coaxial with the rotative member; a speed change gear
mechanism for transmitting the rotation of the rotative
member to the trapezoid prism to drive the trapezoid
prism at an angular velocity half that of the rotative
member; reflectors respectively provided on the en
trance surface side and the exit surface side of the trape
zoid prism so as to re?ect the light from a region outside
an aperture of the trapezoid prism and guide the light to
the trapezoid prism with the light in the aperture paral
lel to the longitudinal axis of the trapezoid prism, on the
one hand and to re?ect the light from the prism to a 20
region outside the aperture of the prism, on the other
hand; a plurality of pairs of convergent lenses, the con
vergent lenses of each pair respectively provided on the
rotative member and the ?xed member, and adapted to
vergent lenses, one of the convergent lenses of each pair
provided for the rotative member and the other to the
?xed member and two lenses of each pair adapted to
optically face each other via the trapezoid’ prism with
one reflector being between each ?ber and the entrance
and exit surfaces of the trapezoid prism, so as to couple
the entrance side optical ?bers with the ?xed member as
well as the exit side optical ?bers with the rotative
member.
‘
According to a second aspect of the present inven
tion, there is provided a multi-port ?beroptic rotary
joint including a trapezoid prism provided between a
optically face each other via the entrance and exit sur 25 rotative member and a ?xed member so that it may be
rotatable relative to the rotative member and coaxial
faces of the trapezoid prism, the re?ectors being located
between each lens and the prism surface; and entrance
and exit side optical ?bers respectively coupled with the
entrance and exit side convergent lenses.
In accordance with the optical rotary joint of the
present invention, light emanating from the emission
side optical ?ber is collimated through the convergent
lens located at a region outside the aperture of the trape
zoid prism and re?ected by the reflector to change its
with the rotatitve member, a speed change gear mecha
nism for transmitting the rotation of the rotative mem
ber to the trapezoid prism so that the trapezoid prism
may rotate at an angular velocity of half compared with
the rotative member, exit and entrance side optical ?
bers respectively connected in the same number with
the rotative member and the ?xed member, two trun
cated conical mirrors, one of which mirrors is provided
direction so as to be parallel to the axial direction of the 35 between the entrance of the trapezoid prism and the
trapezoid prism and enter the entrance surface of the
trapezoid prism. The incident light changes its optical
path by the t_rapezoid prism, which produces an in
entrance side optical ?bers and the other between the
exit surface of the trapezoid prism and the exit side
optical ?bers, so that the light emanating from the en
verted mirror image between an incident light image
trance side optical ?bers may be reflected once to be
and an emergent light image with respect to an optical
directed into the aperture of the trapezoid prism being
axis, so as to propagate in the axial direction of the
parallel to the axis of the prism, and a plurality of pairs
of convergent lenses, one of the convergent lenses of
each pair provided to the rotative member and the other
to the ?xed member and two of each pair adapted to
trapezoid prism and emanate from the exit surface of the
prism. The light emanating from the exit surface of the
trapezoid prism is reflected by the reflector, and guided
to the convergent lens disposed at the region outside the 45 optically face each other via the reflector, the trapezoid
aperture of the trapezoid prism for coupling thereof
with the receiving side optical ?ber.
The trapezoid prism is rotated at an angular velocity
which is half that of the rotative member, so that a
rotating image on the rotator side is altered to a station
ary one by the trapezoid prism and transmitted to the
?xed member side. Conversely, the stationary image on
the ?xed member side is altered to a rotating image
rotating at the same angular velocity as that of the rota
prism, and the reflector, so as to couple the entrance
side optical ?bers with the ?xed member as well as
coupling the exit side optical ?bers with the rotative
member.
These and other aspects, objects and advantages of
the present invention will be more fully understood by
reference to the following detailed description'taken in
conjunction with various ?gures and appended claims.
tor and transmitted to the rotator side. This enables a
BRIEF DESCRIPTION OF THE DRAWINGS
desirable coupling between the emission side optical
?bers of the stationary member and receiving side opti
The accompanying drawings form an integral part of
the description of the preferred embodiments and are
read in conjunction therewith. Like reference numerals
designate identical components in the different Figures,
cal ?bers of the rotative member even when the rotative
member rotates.
According to a ?rst aspect of this invention, there is
provided a multi-port ?beroptic rotary joint comprising
a trapezoid prism provided between a rotative member
and a ?xed member so as to be rotatable relative to the
where:
FIGS. 1 and 2 are longitudinal sectional views re
spectively illustrating prior multi-port ?beroptic rotary
joints;
rotative member and coaxial with the rotative member,
FIG. 3 is a view illustrating a relationship between
a speed change gear mechanism for transmitting the 65 convergent lenses distance and coupling loss;
rotation of the rotative member to the trapezoid prism
FIG. 4 is a longitudinal sectionl view illustrating an
so as to rotate the trapezoid prism at an angular velocity
embodiment of a multi-port ?beroptic rotary joint ac
which is half that of the rotative member, exit and en
cording to the present invention;
5
4,872,737
FIGS. 5 through 7 are sectional views illustrating
another embodiment of a re?ector of the multi-port
an entrance surface 3a of the trapezoid prism 3 in a
?beroptic rotary joint of the present invention respec
direction parallel to the axis of the trapezoid prism 3.
The light through the entrance surface 3a is totally
tively;
FIG. 8 is a longitudinal cross-sectional view illustrat
6
located inward of the aperture of the same so as to enter
5
ing another embodiment of the multi-port ?beroptic
rotary joint of the present invention;
FIGS. 9A and 9B are enlarged views in part of FIG.
8 respectively.
DESCRIPTION OF THE PREFERRED
re?ected at the bottom surface 3b, refracted at the exit
surface 30 to proceed parallel to the optical axis of the
trapezoid prism and reach the rhomboid prism 31b, and
is totally re?ected twice in the same manner as in the
above description inside the same prism so as to propa
gate from the convergent lens 10b to the exit side opti
cal ?ber 14b. The description is also applicable to the
other pairs of entrance and exit side optical ?bers. When
EMBODIMENTS
As illustrated in FIG. 4, a ?xed member 1 rotably
supports a rotator 2 inserted partly therein. Inside the
?xed member 1 a prism holder 4 is positioned to be 15
the rotator 2 is rotated at an angular velocity to, the
coaxial with the rotator 2 so as to support a trapezoid
(%)w by the speed change gear mechanism 22. Hereby,
prism 3. Ends of the prism holder 4 are supported re
spectively on the ?xed member 1 and the rotator 2 via
an optical image on the rotator 2 side becomes station
ary when viewed from the ?xed member 1 side as dis
bearings. Convergent lenses 9a, 9b, 9c, etc., housed in
closed in depth in Japanese Utility Model application
Koukoku (second publication) No. 61-24961
receptacles 15a, 15b, 150, etc., are disposed on an axis
parallel to a prism optical axis to the entrance surface 3a
side of the trapezoid prism 3. Rhomboid prisms 30a,
prism holder 4 and the trapezoid prism 3 are driven for
rotation in the same direction at an angular velocity of
(24961/ 1986). This accordingly assures proper connec
tion between a plurality of pairs of the exit and entrance
30b, 300, etc., which serve as re?ectors, are mounted on
side optical ?bers 5 and 14 irrespective of the rotation of
the ?xed member 1 between the trapezoid prism 3 and
the rotator 2.
the convergent lenses 9. The rhomboid prism 30 has 25
In the case where the optical ?bers have four ports as
both ends ?nished as totally re?ective surfaces each
illustrated in FIG. 4, the mounting pitch between two
with an angle of de?ection of 90 degrees. Likewise,
adjacent plugs 20 is 16 mm when consideration is given
convergent lenses 10a, 10b, 100, etc., housed in recepta
to space for insertion and removal of the plugs 20, etc.
cles 16a, 16b, 160, etc., are located on an axis parallel to
Also, the aperture S3 of the trapezoid prism 3 is given as
the prism axis to the exit surface 30 side of the trapezoid
twelve mm when the rhomboid prism 30, ?ve mm
prism 3, and rhomboid prisms 31a, 31b, 31c are mounted
square, is employed, and the length 13 (1:4.23 XS) is
to the rotator 2 between the prism 3 and the convergent
given as 50.8 mm when the angle of de?ection of the
lenses 10. The convergent lenses 9 and 10 housed in the
prism is fourty-?ve degrees. The optical path in the
receptacles 15 and 16, and entrance and exit side optical
rhomboid prisms 30 and 31 being added to 13, the dis
?bers 5 and 14 having ferrules 6 and 13 of plugs 20 and 35 tance between the convergent lenses 9 and 10 becomes
21 are optically coupled with each other by screwing
sixty-eight mm. Thus, coupling loss is 3.3 dB according
the plugs 20 and 21 on the receptacles 15 and 16. A
to FIG. 3, which is about half compared with the situa
speed changegear mechanism 22 is provided inside the
tion of FIG. 1 where the entrance and exit side optical
?xed member 1 around the prism holder 4 so as to decel
?bers are directly connected with the trapezoid prism
erate the rotation of the rotator 2 to half (in the same 40 through the optical connector (in the case of four ports,
direction) and transmit it to the prism holder 4. The
the coupling loss is between 6 and 7 dB when 1:84
speed change gear mechanism 22 mainly comprises a
mm). Additionally, in the case of a six-port optical ?ber,
gear 23 attached around the rotator 2, a gear 24 at
the distance between the optical connectors becomes
tached onto a shaft 27 supported rotatably in the ?xed
twenty-two mm with the aperture S3 of the trapezoid
member 1 and engaged with the gear 23, and a gear 25 45 prism being thirteen mm. This length being added to the
provided on the shaft 27 and engaged with a gear 26
optical path length of the rhomboid prism, the distance
formed in the central outer periphery of the prism
L between the convergent lenses of FIG. 3 becomes
holder 4. The gears 24,25 as intermediate ones are di
seventy mm with the coupling loss being 4.0 dB. When
vided respectively into gears 24a and 24b, and 25a and
the intermediate optical ?bers 8 and 11 of FIG. 2 are
25b so as to produce relative rotational displacement in
employed, the aperture S of the trapezoid prism be
the direction of rotation thereof, between which di
comes thirteen mm in a six-port case. Although the
vided gears a resilient member such as a spring is pro
vided for biasing those divided gears in a direction the
coupling loss in this case is as small as 2.0 dB, there is
another coupling loss of two dB at the entrance and exit
displacement is to be produced. Here, designated at 28
ends of the intermediate optical ?bers 8 and 11 8 (optical
is a rod for transmitting the rotative power of the r'otary 55 connector coupling loss is generally one dB/one con
element (not shown) to the rotator 2 for optical trans
nection). This brings about an insertion loss of four dB
mission.
in total, the same as in the rhomboid prism of FIG. 4.
Light emanating from the outgoing side optical ?ber
However, since the total length L1 of the rotary joint of
5a is collimated by the convergent lens 9a and allowed
to enter the side face of the rhomboid prism 30a. The
FIG. 2 becomes three times as long as the length 01 of
light entering the rhomboid prism 30a is entirely re
length of from sixty to eighty mm (a value when an
optimum offset is taken into consideration in view of the
assurance of the workability upon fabrication of the
?ber) is added thereto. Thus, a system using the inter
?ected at one end surface of the rhomboid prism 30a
located at a position external of the aperture of the
trapezoid prism 3 to alter its direction of propagation at
right angle and advance along the axis of the rhomboid
prism 30a (in the radial direction of the trapezoid prism
the trapezoid prism 3 if the intermediate optical ?bers
mediate optical ?bers is disadvantageous compared
3). And thereafter, the light is totally re?ected by 90
with the present invention, namely a system using re
?ection of the light, from the viewpoint of the cost and
degrees at the other end of the trapezoid prism 30a
the handling properties thereof.
7
4,872,737
The intermediate gear 24 of the speed change mecha
nism 22 is divided into two gears, two gears having
close contact with each, and those divided gears are
biassed by a spring, or the like, so as to relatively pro
duce rotational displacement. The intermediate gear 25
trapezoid prism 3 and the prism holder 4. The dry gas
fed through the through-hole 10 reaches the air gap 37,
with which gas surfaces of the trapezoid prism 3 and the
rhomboid prism 30 are prevented from being subject to
is constructed in the same fashion as gear 24. This
causes the engagement surfaces of the gears 24 and 25 to
be always in contact with the engagement surfaces of
the gears 23 and 26, preventing any backlash. Accord
ingly, mismatching of the optical axes of the entrance
and exit side optical ?bers can be prevented when the
rotator 2 is rotated normally and reversely, thus im
8
cylinder-shaped, as illustrated in FIGS. 9A and 98,
with its inner diameter d larger than the height h and
width f of the rectangle-shaped, in cross section, trape
zoid prism 3. This is to form an air gap 37 between the
moisture condensation even when the external environ
O
proving the performance of optical transmission. Al
though in the embodiment described above the speed
ment around the rotary joint satis?es the conditions for
moisture condensation. Here, such dry gas may be sup
plied only when circumstances demand it. On the other
hand, the dry gas may be supplied at all times, in which
case, hydrodynamic resistance is produced owing to
bearings 36c, 36d to make the space 39 slightly higher in
pneumatic pressure than the atmosphere of space where
the gears 24, 25 are disposed, thus preventing dust from
compact.
I
entering the space 39 in which the traezoid prism 3 is
Several other embodiments of this invention will be
installed. The prevention of dew formation in the opti
now described.
20
cal
joint is important from the viewpoint of each end
FIG. 5 illustrates another embodiment wherein a
surface of the prism subjected to moisture causing inci
mirror 32 as the re?ector is disposed between the trape
dent and emergent angles of light to be changed because
zoid prism 3 and the emission optical ?ber 5. The opti
change gear mechanism 22 is constructed by a combina
tion of spur gears, a planetary gear mechanism shown in
FIG. 1 may be employed for making the device more
of the presence of water which allows the optical cou
cal ?ber 5 and the convergent lens 9 are arranged at the
pling
loss to increase. Meanwhile, heater means may be
angle 0 (ranging from zero to ninty degrees) with re 25
utilized to prevent such moisture condensation.
spect to the optical axis of the trapezoid prism 3, and the
With reference to FIG. 8 again, another rotative
light from the convergent lens 9 is re?ected in a direc
member 32 is provided between the rotator 2 and the
tion parallel to the optical axis of the trapezoid prism 3.
rod 28 while a ?exible coupling 33 such for example as
Another mirror (not shown) is likewise provided on the
metal bellows is provided between rotative member 32
side of the exit surface 30 of the trapezoid prism 3. Such
and the rotator 2. With this structure, abnormal drive
use of the mirror 32 assures the installation of a consid
force such as torsion and thrust force is absorbed by the
erable number of optical ?bers 5 even if the aperture S
?exible coupling 33 so as to prevent transmission
of the trapezoid prism 3 is small, while shortening the
thereof to the rotator 2 even if abnormal driving force is
distance between the convergent lenses 9 and 10 accom
panying a reduction of the coupling loss.
35 applied to the rod 28. That is, only the radial turning
force is applied to the rotator 2. If such abnormal driv
FIG. 6 illustrates a device employing two truncated
ing force is transmitted to the rotator 2, then undue
conical prisms, one for each side, instead of plural
force is applied to the bearings 36b, 360 which support
rhomboid prisms of FIG. 4 between the trapezoid rism
the rotator 2 to distort the optical path increasing the
3 and the entrance and exit side optical ?bers 5, 14.
While in FIG. 4, one rhomboid prism 30, 31 is installed 40 coupling loss. This also shortens the longevity of the
bearings 36b and 360.
to one optical ?ber, only one prism 33 is installed in
It is expected as a matter of course that the preferred
FIG. 6 irrespective to the number of the optical ?bers.
embodiments selected to describe the present invention
This results in easy adjustment of the optical axis as well
may be subjected to any number of various modi?ca
as reduction of the number of parts and the cost.
FIG. 7 illustrates still another modi?cation of the 45 tions or additions by those skilled in the art without
departing the spirit and scope of the present invention.
embodiment wherein mirrors 34, 35 having conical
For example, the re?ector 30a provided between the
re?ecting surfaces are disposed on different levels be
optical ?ber 5a and the trapezoid prism 3 is not limited
tween the optical ?ber 5 and the trapezoid prism 3.
to the foregoing rhomboid prism and truncated conical
Light from the optical ?ber 5 is collimated through the
mirror_ insofar as an alternative element therefor can
convergent lens 9, and the resulting bundle of rays is
properly guide the light from the optical ?ber 5a to the
reflected inward by the ?rst-stage mirror 34 and made
trapezoid prism 3 and from the trapezoid prism 3 to the
parallel to the optical axis of the trapezoid prism 3 by
the second-stage mirror 35. Hereby, it is made possible
re?ector 31a. Thus, the protection sought herein is
to bring the convergent lens 9 close to the trapezoid
intended to cover all the details claimed in the appended
prism, which can reduce the total length L2 of the ro
claims and those equivalent thereto.
tary joint.
What is claimed is:
FIG. 8 illustrates a multi-port ?beroptic rotary joint
1. A multi-port ?beroptic rotary joint of the type
of FIG. 4 further including dewing prevention means.
having a ?xed member and a rotative member, compris
The ?xed member 1 has a through hole 10 bored in a
wall thereof near the receptacle 15b. One end of the
through hole 10 reaches space 39 between the trapezoid
prism 3 and the rhomboid prism 30 while the other end
thereof reaches the outer surface of the ?xed member 1.
A pipe 35 is connected to said the other end of the
through hole 1c. The space 39 formed between the 65
trapezoid prism 30 is ?lled with dry gas (not shown)
supplied through the through hole 10 as indicated by the
arrow 36. The prism holder 4 of FIG. 8 is hollow and
ing:
a trapezoid prism having an aperture, an entrance
side, an exit side and an optical axis, said prism
being disposed between the rotative member and
the ?xed member of the rotary joint so as to be
rotatable relative to said rotative member and co
axial with said rotative member;
a speed change gear mechanism for transmitting the
rotation of said rotative member to the trapezoid
prism to rotate the trapezoid prism at an angular
4,872,737
.
velocity half the angular velocity of said rotative
member;
re?ector means provided on the entrance side of the
trapezoid prism so as to optically guide the light
coming from a region outside the aperture of said
10
9. A multi-port ?beroptic joint of claim 1, wherein a
passage is provided in said ?xed member, the passage
communicating with a space between the entrance sur
face of the trapezoid prism and the re?ector means
5
trapezoid prism to the trapezoid prism such that
the light is parallel to the axis of the trapezoid
prism within the aperture thereof, and re?ector
disposed on said entrance surface side, so that said gap
and said space may be supplied with gas whose temper
ature is above a predetermined value when external
temperature is under another predetermined value.
means provided on the exit side of the trapezoid
10. A multi-port ?beroptic rotary joint of claim 1,
prism so as to optically guide the light emanating
from the trapezoid prism to a region outside the
wherein said second gear is divided into a ?rst set of
two gears, and a ?rst resilient member is provided be
aperture of said trapezoid prism;
tween said ?rst set of two gears so as to produce rota
a plurality of pairs of convergent lenses respectively
tional displacement between said two gears, and said
provided on the rotative member and the ?xed
fourth gear is divided into a second set of two gears, and
member, the convergent lenses of each pair opti 15 a second resilient member is provided between said
cally facing the entrance and exit surfaces of the
second set of two gears so as to produce rotational
trapezoid prism via the re?ector means and opti
displacement between said second set of two gears.
cally facing each other, the convergent lenses in
each pair thereof being spaced apart a distance
greater than the width of the aperture of said trape
zoid prism; and
11. A multi-port ?beroptic rotary joint of claim 2,
entrance and exit side optical ?bers respectively con
further including a rotative element positioned between
said rotative member and a member for transmitting
turning force to the rotative member, said rotative ele
ment being rotated together with said member and
nected to the entrance and exit surface side conver
rotatable with respect to said rotative member, and a
gent lenses.
?exible coupling for connecting said rotative element
2. A multi-port ?beroptic rotary joint of claim 1, 25 with the rotative member.
wherein said re?ector means is a rhomboid prism
12. A multi-port ?beroptic rotary joint of claim 3,
formed to provide an angle of de?ection of 90 degrees
further including a rotative element positioned between
only twice to the light incident thereupon, one re?ector
said rotative member and a member for transmitting
means being provided for each optical ?ber.
turning force to the rotative member, said rotative ele
3. A multi-port ?beroptic rotary joint of claim 1, 30 ment being rotated together with said member and
wherein said re?ector means is a truncated conical mir
rotatable with respect to said rotative member, and a
ror formed to re?ect the light incident thereupon only
?exible coupling for connecting said rotative element
once, said re?ector means being two in total number,
one re?ector means being provided for all the entrance
with the rotative member.
13. A multi-port ?beroptic rotary joint of claim 4,
said optical ?bers, the other re?ector means being pro 35 further including a rotative element positioned between
vided for all the exit side optical ?bers.
said rotative member and a member for transmitting
4. A multi-port ?beroptic rotary joint of claim 1,
turning force to the rotative member, said rotative ele
wherein said re?ector means is a truncated conical mir
ment being rotated together with said member and
ror formed toqre?ect the light incident thereupon only
rotatable with respect to said rotative member, and a
once, the re?ector means being four in total number, 40 ?exible coupling for connecting said rotative element
two of said re?ector means being provided for all the
with the rotative member.
entrance optical ?bers, the remaining two of said re?ec
14. A multi-port ?beroptic rotary joint of claim 2,
tor means being provided for all the exit optical ?bers.
including a holder for supporting said trapezoid prism
5. A multi-port ?beroptic rotary joint of claim 1,
further including a rotative element positioned between
said rotative member and a member for transmitting
turning force to the rotative member, said rotative ele
ment being rotated together with said member and
so as to be rotatable relative to said rotative member and
45
said ?xed member.
15. A multi-port ?beroptic rotary joint of claim 3,
including a holder for supporting said trapezoid prism
so as to be rotatable relative to said rotative member and
rotatable with respect to said rotative member, and a
said ?xed member.
?exible coupling for connecting said rotative element
with the rotative member.
16. A multi-port ?beroptic rotary joint of claim 4,
including a holder for supporting said trapezoid prism
6. A multi-port ?beroptic rotary joint of claim 1,
including a holder for supporting said trapezoid prism
said ?xed member.
so as to be rotatable relative to said rotative member and
so as to be rotatable relative to said rotative member and
said ?xed member.
7. A multi-port ?beroptic rotary joint of claim 1,
wherein said speed change gear mechanism includes a
?rst gear disposed at the outer periphery of the rotative
55
17. A multi-port ?beroptic rotary joint of claim 5,
including a holder for supporting said trapezoid prism
so as to be rotatable relative to said rotative member and
said ?xed member.
18. A multi-port ?beroptic rotary joint of claim 2,
member, a shaft supported rotatably in said ?xed mem
ber, a second gear disposed on said shaft for engage
ment with said ?rst gear, a third gear provided at the
outer periphery of said holder, and a fourth gear dis
posed on said shaft for engagement with said third gear.
wherein said speed change gear mechanism includes a
?rst gear disposed at the outer periphery of the rotative
member, a shaft supported rotatably in said ?xed mem
ber, a second gear disposed on said shaft for engage
ment with said ?rst gear, a third gear provided at the
8. A multi-port ?beroptic rotary joint of claim 1,
outer periphery of said holder, and a fourth gear dis
wherein a gap is provided between the surface of the 65 posed on said shaft for engagement with said third gear.
trapezoid prism and the inner peripheral wall of the
holder upon housing of the trapezoid prism in the
holder.
19. A multi-port ?beroptic rotary joint of claim 3,
wherein said speed change gear mechanism includes a
first gear disposed at the outer periphery of the rotative
11
4,872,737
member, a shaft supported rotatably in said ?xed mem
ber, a second gear disposed on said shaft for engage
ment with said ?rst gear, a third gear provided at the
outer periphery of said holder, and a fourth gear dis
posed on said shaft for engagement with said third gear.
12
30. A multi-port ?beroptic joint of claim 3, wherein a
passage is provided in said ?xed member, the passage
communicating with a space between the entrance sur
face of the trapezoid prism and the re?ector means
disposed on said entrance surface side, so that said gap
20. A multi-port ?beroptic rotary joint of claim 4,
and said space may be supplied with gas whose temper
ature is above a predetermined value when external
wherein said speed change gear mechanism includes a
?rst gear disposed at the outer periphery of the rotative
member, a shaft supported rotatably in said ?xed mem
temperature is under another predetermined value.
31. A multi-port ?beroptic joint of claim 4, wherein a
ber, a second gear disposed on said shaft for engage 10 passage is provided in said ?xed member, the passage
ment with said ?rst gear, a third gear provided at the
communicating with a space between the entrance sur
outer periphery of said holder, and a fourth gear dis
posed on said shaft for engagement with sai third gear.
face of the trapezoid prism and the reflector means
disposed on said entrance surface side, so that said gap
21. A multi-port ?beroptic rotary joint of claim 5,
and said space may be supplied with gas whose temper
wherein said speed change gear mechanism includes a
?rst gear disposed at the outer periphery of the rotative
member, a shaft supported rotatably in said ?xed mem
ature is above a predetermined value when external
temperature is under another predetermined value.
32. A multi-port ?beroptic joint of claim 5, wherein a
passage is provided in said ?xed member, the passage
ber, a second gear disposed on said shaft for engage
ment with said ?rst gear, a third gear provided at the
outer periphery of said holder, and a fourth gear dis
posed on said shaft for engagement with said third gear.
communicating with a space between the entrance sur
face of the trapezoid prism and the re?ector means
disposed on said entrance surface side, so that said gap
and said space may be supplied with gas whose temper
22. A multi-port ?beroptic rotary joint of claim 6,
ature is above a predetermined value when external
wherein said speed change gear mechanism includes a
?rst gear disposed at the outer periphery of the rotative
member, a shaft supported rotatably in said ?xed mem
ber, a second gear disposed on said shaft for engage
temperature is under another predetermined value.
33. A multi-port ?beroptic joint of claim 6, wherein a
passage is provided in said ?xed member, the passage
communicating with a space between the entrance sur
ment with said ?rst gear, a third gear provided at the
outer periphery of said holder, and a fourth gear dis
posed on said shaft for engagement with said third gear.
face of the trapezoid prism and the reflector means
disposed on said entrance surface side, so that said gap
and said space may be supplied with gas whose temper
23. A multi-port ?beroptic rotary joint of claim 2,
ature is above a predetermined value when external
wherein a gap is provided between the surface of the
temperature is under another predetermined value.
34. A multi-port ?beroptic joint of claim 7, wherein a
passage is provided in said ?xed member, the passage
trapezoid prism and the inner peripheral wall of the
holder upon housing of the trapezoid prism in the
holder.
24. A multi-port ?beroptic rotary joint of claim 3,
35 communicating with a space between the entrance sur
face of the trapezoid prism and the reflector means
wherein a gap is provided between the surface of the
disposed on said entrance surface side, so that said gap
trapezoid prism and the inner peripheral wall of the
holder upon‘housing of the trapezoid prism in the
holder.
25. A multi-port ?beroptic rotary joint of claim 4,
wherein a gap is provided between the surface of the
trapezoid prism and the inner peripheral wall of the
holder upon housing of the trapezoid prism in the
holder.
26. A multi-port ?beroptic rotary joint of claim 5,
wherein a gap is provided between the surface of the
trapezoid prism and the inner peripheral wall of the
holder upon housing of the trapezoid prism in the
holder.
27. A multi-port ?beroptic rotary joint of claim 6,
wherein a gap is provided between the surface of the
trapezoid prism and the inner peripheral wall of the
holder upon housing of the trapezoid prism in the
holder.
28. A multi-port ?beroptic rotary joint of claim 7,
wherein a gap is provided between the surface of the
trapezoid prism and the inner peripheral wall of the
holder upon housing of the trapezoid prism in the
and said space may be supplied with gas whose temper
ature is above a predetermined value when external
40
temperature is under another predetermined value.
35. A multi-port ?beroptic joint of claim 8, wherein a
passage is provided in said ?xed member, the passage
communicating with a space between the entrance sur
face of the trapezoid prism and the reflector means
45 disposed on said entrance surface side, so that said gap
and said space may be supplied with gas whose temper
ature is above a predetermined value when external
temperature is under another predetermined value.
36. A multi-port ?beroptic rotary joint of claim 2,
wherein said second gear is divided into a ?rst set of
two gears, and a ?rst resilient member is provided be
tween said ?rst set of two gears so as to produce rota
tional displacement between said two gears, and said
fourth gear is divided into a second set of two gears, and
55 a second resilient member is provided between said
second set of two gears so as to produce rotational
displacement between said second set of two gears.
37. A multi-port ?beroptic rotary joint of claim 3,
wherein said second gear is divided into a ?rst set of
two gears, and a ?rst resilient member is provided be
holder.
29. A multi-port ?beroptic joint of claim 2, wherein a
passage is provided in said ?xed member, the passage
tween said ?rst set of two gears so as to produce rota
communicating with a space between the entrance sur
fourth gear is divided into a second set of two gears, and
tional displacement between said two gears, and said
face of the trapezoid prism and the re?ector means
a second resilient member is provided between said
disposed on said entrance surface side, so that said gap 65 second set of two gears so as to produce rotational
and said space may be supplied with gas whose temper
displacement between said second set of two gears.
ature is above a predetermined value when external
38. A multi-port ?beroptic rotary joint of claim 4,
temperature is under another predetermined value.
wherein said second gear is divided into a ?rst set of
13
4,872,737
14
two gears, and a ?rst resilient member is provided be
coming from a region outside the aperture of said
tween said ?rst set of two gears so as to produce rota
trapezoid prism to the trapezoid prism such that
tional displacement between said two gears, and said
fourth gear is divided into a second set of two gears, and
the light is parallel to the axis of the trapezoid
prism within the aperture thereof, and reflector
a second resilient member is provided between said
means provided on the exit side of the trapezoid
second set of two gears so as to produce rotational
prism so as to optically guide the light emanating
from the trapezoid prism so as to optically guide
the light emanating from the trapezoid prism to a
displacement between said second set of two gears.
39. A multi-port ?beroptic rotary joint of claim 5,
wherein said second gear is divided into a ?rst set of
two gears, and a ?rst resilient member is provided be 10
tween said ?rst set of two gears so as to produce rota
tional displacement between said two gears, and said
fourth gear is divided into a second set of two gears, and
a second resilient member is provided between said
second set of two gears so as to produce rotational
displacement between said second set of two gears.
40. A multi-port ?beroptic rotary joint of claim 6,
wherein said second gear is divided into a ?rst set of
two gears, and a ?rst resilient member is provided be
tween said ?rst set of two gears so as to produce rota 20
region outside the aperture of said trapezoid prism,
said re?ector means including a truncated conical
mirror formed to re?ect the light incident there
upon only once, said reflector means being two in
total number, one re?ector means being provided
for all the entrance optical ?bers, the other re?ec
tor means being provided for all of the exit optical
?bers;
a plurality of pairs of convergent lenses respectively
provided on the rotative member and the ?xed
member, the convergent lenses of each pair opti
cally facing the entrance and exit surfaces of the
trapezoid prism via the re?ector means and opti
tional displacement between said two gears,'and said
fourth gear is divided into a second set of two gears, and
cally facing each other; and
a second resilient member is provided between said
entrance and exit side optical ?bers respectively con
second set of two gears so as to produce rotational
displacement between said second set of two gears.
nected to the entrance and exit surface side conver
25
gent lenses.
45. A multi-port ?beroptic rotary joint of the type
41. A multi-port ?beroptic rotary joint of claim 7,
wherein said second gear is divided into a ?rst set of
having a ?xed member and a rotative member, compris
two gears, and a ?rst resilient member is provided be
tween said ?rst set of two gears so as to produce rota
ing:
tional displacement between said two gears, and said
a trapezoid prism having an aperture, an entrance
fourth gear is divided into a second set of two gears, and
a second resilient member is provided between said
side, an exit side and an optical axis, said prism
being disposed between the rotative member and
second set of two gears so as to produce rotational
the ?xed member of the rotary joint so as to be
rotatable relative to said rotative member and co
displacement between said second set of two gears.
42. A multi-port ?beroptic rotary joint of claim 8,
tional displacement between said two gears, and said
axial with said rotative member;
a speed change gear mechanism for transmitting the
rotation of said rotative member to the trapezoid
prism to rotate the trapezoid prism at an angular
velocity half the angular velocity of said rotative
fourth gear is divided into a second set of two gears, and
a second resilient member is provided between said
re?ector means provided on the entrance side of the
wherein said second gear is divided into a ?rst set of
two gears, and a ?rst resilient member is provided be
tween said ?rst set of two gears so as to produce rota
member;
second set of two gears so as to produce rotational
trapezoid prism so as to optically guide the light
coming from a region outside the aperture of said
displacement between said second set of two gears.
43. A multi-port ?beroptic rotary joint of claim 9,
wherein said second gear is divided into a ?rst set of 45
two gears, and a ?rst resilient member is provided be
tween said ?rst set of two gears so as to produce rota
means provided on the exit side of the trapezoid
tional displacement between said two gears, and said
prism so as to optically guide the light emanating
from the trapezoid prism so as to optically guide
the light emanating from the trapezoid prism to a
fourth gear is divided into a second set of two gears, and
a second resilient member is provided between said
second set of two gears so as to produce rotational
region outside the aperture of said trapezoid prism,
displacement between said second set of two gears.
said re?ector means including a truncated conical
44. A multi-port ?beroptic rotary joint of the type
having a ?xed member and a rotative member, compris
ing:
55
a trapezoid prism having an aperture, an entrance
trapezoid prism to the trapezoid prism such that
the light is parallel to the axis of the trapezoid
prism within the aperture thereof, and re?ector
mirror formed to re?ect the light incident there
upon only once, the re?ector means being four in
total number, two of said re?ector means being
side, an exit side and an optical axis, said prism
being disposed between the rotative member and
provided for all of the entrance optical ?bers, the
the ?xed member of the rotary joint so. as to be
rotatable relative to said rotative member and co
vided for all of the exit optical ?bers;
a plurality of pairs of convergent lenses respectively
axial with said rotative member;
a speed change gear mechanism for transmitting the
provided on the rotative member and the ?xed
rotation of said rotative member to the trapezoid
prism to rotate the trapezoid prism at an angular
cally facing the entrance and exit surfaces of the
trapezoid prism via the re?ector means and opti
velocity half the angular velocity of said rotative
member;
re?ector means provided on the entrance side of the
trapezoid prism so as to optically guide the light
remaining two of said re?ector means being pro
member, the convergent lenses of each pair opti
cally facing each other; and
entrance and exit side optical ?bers respectively con
nected to the entrance and exit surface side conver
gent lenses.
15
4,872,737
46. A multi-port ?beroptic rotary joint of the type
having a ?xed member and a rotative member, compris-
16
prism so as to optically guide the light emanating
from the trapezoid prism to a region outside the
ing:
aperture of said trapezoid prism;
a trapezoid prism having an aperture, an entrance
side, an exit side and an optical axis, said prism 5
a plurality of pairs of convergent lenses respectively
provided on the rotative member and the ?xed
being disposed between the rotative member and
member, the convergent lenses of each pair opti
the ?xed member of the rotary joint so as to be
rotatable relative to said rotative member and co-
cally facing the entrance and exit surfaces of the
trapezoid prism via the reflector means and opti
axial with said rotative member;
cally facing each other; and
a speed change gear mechanism for transmitting the 10
rotation of said rotative member to the trapezoid
prism to rotate the trapezoid prism at an angular
velocity half the angular velocity of said rotative
entrance and exit side optical ?bers respectively con
nected to the entrance and exit surface side conver
gent lenses.
48. A multi-port ?beroptic rotary joint of the type
member;
having a ?xed member and a rotative member, compris
re?ector means provided on the entrance side of the 15 ing:
trapezoid prism so as to optically guide the light
coming from a region outside the aperture of said
a trapezoid prism having an aperture, an entrance
side, an exit side and an optical axis, said prism
trapezoid prism to the trapezoid prism such that
the light is parallel to the axis of the trapezoid
being disposed between the rotative member and
prism within the aperture thereof, and re?ector 20
means provided on the exit side of the trapezoid
prism so as to optically guide the light emanating
from the trapezoid prism to a region outside the
aperture of said trapezoid prism;
a plurality of pairs of convergent lenses respectively 25
provided on the rotative member and the ?xed
member, the convergent lenses of each pair optically facing the entrance and exit surfaces of the
trapezoid prism via the re?ector means and opti-
cally facing each other;
the ?xed member of the rotary joint so as to be
rotatable relative to said rotative member and co
axial with said rotative member;
a speed change gear mechanism for transmitting the
rotation of said rotative member to the trapezoid
prism to rotate the trapezoid prism at an angular
velocity half the angular velocity of said rotative
member;
re?ector means provided on the entrance side of the
trapezoid prism so as to optically guide the light
coming from a region outside the aperture of said
30
trapezoid prism to the trapezoid prism such that
entrance and exit side optical ?bers respectively con-
the light is parallel to the axis of the trapezoid
nected to the entrance and exit surface side convergent lenses; and,
a rotative element positioned between said rotative
member and a member for transmitting turning 35
prism within the aperture thereof, and reflector
means provided on the exit side of the trapezoid
prism so as to optically guide the light emanating
from the trapezoid prism to a region outside the
force to the rotative member, said rotative element
being rotated together with said member and rotat-
aperture of said trapezoid prism;
a plurality of pairs of convergent lenses respectively
able withrrespect to said rotative member, and a
provided on the rotative member and the ?xed
flexible c—oupling for connecting said rotative ele-
member, the convergent lenses of each pair opti
ment with the rotative member.
40
47. A multi-port ?beroptic rotary joint of the type
having a ?xed member and a rotative member, comprising:
cally facing the entrance and exit surfaces of the
trapezoid prism via the re?ector means and opti
cally facing each other; and
entrance and exit side optical ?bers respectively con
a trapezoid prism having an aperture, an entrance
nected to the entrance and exit surface side conver
side, an exit side and an optical axis, said prism 45
being disposed between the rotative member and
gent lenses,
there being provided a passage in said ?xed member,
the ?xed member of the rotary joint so as to be
rotatable relative to said rotative member and coaxial with said rotative member;
a speed change gear mechanism for transmitting the 50
rotation of said rotative member to the trapezoid
prism to rotate the trapezoid prism at an angular
the passage communicating with a space between
the entrance surface of the trapezoid prism and the
re?ector means disposed on said entrance surface
side, so that said gap and said space may be sup
plied with gas whose temperature is above a prede
termined value when the external temperature is
velocity half the angular velocity of said rotative
member, said speed change gear mechanism in-
under another predetermined value.
49. A multi-port ?beroptic rotary joint of the type
cluding a ?rst gear disposed at the outer periphery 55 having a ?xed member and a rotative member, compris
of the rotative member, a shaft rotatably supported
ing:
in said ?xed member, a second gear disposed on
said shaft for engagement with said ?rst gear, a
a trapezoid prism having an aperture, an entrance
side, an exit side and an optical axis, said prism
third gear provided at the outer periphery of said
being disposed between the rotative member and
holder, and a fourth gear disposed on said shaft for 60
engagement with said third gear;
re?ector means provided on the entrance side of the
the ?xed member of the rotary joint so as to be
rotatable relative to said rotative member and co
axial with said rotative member;
trapezoid prism so as to optically guide the light
coming from a region outside the aperture of said
trapezoid prism to the trapezoid prism such that 65
the light is parallel to the axis of the trapezoid
a speed change gear mechanism for transmitting the
rotation of said rotative member to the trapezoid
prism to rotate the trapezoid prism at an angular
velocity half the angular velocity of said rotative
member, said speed change gear mechanism in
cluding a ?rst gear disposed at the outer periphery
prism within the aperture thereof, and re?ector
means provided on the exit side of the trapezoid
17
4,872,737
of the rotative member, a shaft rotatably supported
18
the ?xed member of the rotary joint so as to be
rotatable relative to said rotative member and co
in said ?xed member, a second gear disposed on
said shaft for engagement with said ?rst gear, a
third gear provided at the outer periphery of said
holder, and a fourth gear disposed on said shaft for 5
engagement with said third gear, said second gear
being divided into a ?rst set of two gears, there
being further provided a ?rst resilient member
axial with said rotative member;
a speed change gear mechanism for transmitting the
rotation of said rotative member to the trapezoid
prism to rotate the trapezoid prism at an angular
velocity half the angular velocity of said rotative
member, said speed change gear mechanism in
between said ?rst set of two gears so as to produce
cluding a ?rst gear disposed at the outer periphery
rotational displacement between said two gears, 10
and said fourth gear being divided into a second set
of two gears, there being further provided asecond
resilient member between said second set of two
gears so as to produce rotational displacement between said second set of two gears;
15
re?ector means provided on the entrance side of the
of the rotative member, a shaft rotatably supported
in said ?xed member, a second gear disposed on
said shaft for engagement with said ?rst gear, a
third gear provided at the outer periphery of said
holder, and a fourth gear disposed on said shaft for
engagement with said third gear;
reflector means provided on the entrance side of the
trapezoid prism so as to optically guide the light
coming from a region outside the aperture of said
trapezoid prism to the trapezoid prism such that
the light is parallel to the axis of the trapezoid 20
prism within the aperture thereof, and re?ector
trapezoid prism so as to optically guide the light
coming from a region outside the aperture of said
trapezoid prism to the trapezoid prism such that
the light is parallel to the axis of the trapezoid
prism within the aperture thereof, and re?ector
means provided on the exit side of the trapezoid
means provided on the exit side of the trapezoid
prism so as to optically guide the light emanating
from the trapezoid prism so as to optically guide
the light emanating from the trapezoid prism to a 25
region outside the aperture of said trapezoid prism;
prism so as to optically guide the light emanating
from the trapezoid prism so as to optically guide
the light emanating from the trapezoid prism to a
region outside the aperture of said trapezoid prism,
a plurality of pairs of convergent lenses respectively
provided on the rotative member and the ?xed
said re?ector means including a rhomboid prism
formed to provide an angle of de?ection of 90
member, the convergent lenses of each pair optically facing the entrance and exit surfaces of the 30
trapezoid prism via the reflector means and optically facing each other; and
degrees only twice to the light incident thereupon,
one reflector means being provided for each opti
cal ?ber;
a plurality of pairs of convergent lenses respectively
entrance and exit side optical ?bers respectively connected to the entrance and exit surface side convergent lenses.
35
provided on the rotative member and the ?xed
member, the convergent lenses of each pair opti
cally facing the entrance and exit surfaces of the
50. A multi-port fiberoptic rotary joint of the type
having a ?xed member and a rotative member, compris-
trapezoid prism via the reflector means and opti
cally facing each other; and
ing:
_
a trapezoid prism having an aperture, an entrance
side, an exit side and an optical axis, said prism 40
being disposed between the rotative member and
entrance and exit side optical ?bers respectively con
nected to the entrance and exit surface side conver
gent lenses.
*
45
5O
55
6O
65
*
*
*
*
UNITED STATES PATENT AND TRADEMARK OFFICE
CERTIFICATE OF CORRECTION
PATENT N0.
:
4, 872, 737
DATED
I
October 10, 1989
INVENTOR(S) :
Toshio Mahori; Hideyuki Takashima; and Hitoshi Morinaga
It is certified that error appears in the above-identified patent and that said Letters Patent is hereby
corrected as shown below:
Claim 44, column 14, lines 7 and 8, delete "so as to optically guide
the light emanating from the trapezoid prism".
Claim 45, column 14, lines 48 and 49, delete "so as to optically guide
the light emanating from the trapezoid prism".
Signed and Sealed this
Twenty-sixth Day of February, 1991
Attest:
HARRY F. MANBECK, JR.
AIICSIiIZg O?‘icer
Commissioner of Parents and Trademarks
UNITED STATES PATENT AND TRADEMARK OFFICE
CERTIFICATE OF CORRECTION‘
PATENT NO.
I
4, 872,737
DATED
:
October 10, 1989
|NVENTOR(S) I
'Ibshio Fukahori, Hideyuki Takashjma, and Hitoshi bbrinaga
It is certified that error appears in the above-identi?ed patent and that said Letters Patent is hereby
corrected as shown below:
'
Column 17, lines 24 and 25, delete "so as to optically guide the
light emanating from the trapezoid prism".
Column 18, lines 24 and 25, delete "so as to optically guide the
light emanating from the trapezoid prism".
Signed and Sealed this
Eighth Day of December, 1992
Altest:
DOUGLAS B. COM ER
Attesting Officer
Acting Commissioner of Parents and Trademarks