Mechanism for extending and contracting antenna

An antenna system is provided with a plurality of telescoped antenna sections which are extended and contracted by an operating wire connected to the uppermost antenna section. The wire is made of a relatively rigid material and has a width of 1.5.about.2.2 times its thickness. There is also provided a clutch for selectively operating the antenna by a motor or the human hand.

BACKGROUND OF THE INVENTION 
The present invention relates to a mechanism for extending and contracting 
an antenna, and more particularly a mechanism for manually or 
automatically extending and contracting an antenna, for example a 
telescope type antenna. 
As is well known, a telescope type antenna is constituted by a plurality of 
tubes having different diameters which are interconnected like a 
telescope. The antenna is extended or contracted by using a wire which 
does not extend and contract. The wire utilized for this purpose has a 
circular cross-sectional configuration. It is advantageous that the wire 
is straight when the antenna is extended. A synthetic resin, for example a 
polyacetal resin, is suitable to form an operating wire having a circular 
cross-section. 
In recent years, a gear is used for extending and contracting the operating 
wire. In this case, the gear is situated at a wire passing port provided 
for a casing containing a drum or at a position just below an antenna base 
cylinder mounting portion. The gear is driven by an electric motor and a 
rack is provided for engaging the gear. Special constructions for driving 
the gear are disclosed in Japanese Utility Model Laid Open Patent 
Specification Nos. 49,942/1974, 155,033/1971 and 36,613/1979. In these 
references, a strip member or the like is substituted for a wire driven by 
the gear, and perforations are provided for the strip member for engaging 
the gear. Furthermore, Japanese Laid Open Patent Specification No. 
29,047/1978 discloses a plastic belt clamped between rollers to be 
extended and contracted by driving the rollers. 
According to Japanese Laid Open Patent Specification No. 90,951/1979, a 
gear is formed on periphery of a large diameter pulley contained in a 
casing, and driven by an electric motor, and a wire push member is 
provided in a range of 90.degree. in the peripheral direction of said 
pulley starting from a position immediately beneath an antenna base 
cylinder, that is an antenna receiving cylinder. Furthermore, a rack is 
formed on one side of said wire so as to mesh the rack with the gear 
provided for the pulley. This reference also shows a construction wherein 
the rear surface of the wire push member is made flat so as to efficiently 
guide the wire push member. 
Further, Japanese Utility Model Laid Open Patent Specification No. 
31,044/1981 discloses a flat rectangular wire which is substituted for a 
conventional wire having a circular cross-section for the purpose of 
neatly accommodating an antenna operating wire in a casing. Since this 
wire is intended to substitute for a conventional circular wire, its 
cross-sectional configuration is approximately square. 
As is well known, the extending and contracting antenna is frequently used 
in motor cars. Such car mounted antenna is extended and contracted by 
manual operation or automatic operation utilizing an electric motor. The 
manual operation has been used for many years. With the motor operation, 
the antenna can be extended and contracted by operating a switch installed 
in a car. Especially, it is convenient when the antenna is expanded and 
contracted in an interlocked relation with the ON.multidot.OFF operation 
of a car radio switch and when it rains, the driver is not required to get 
out of the car for manipulating the antenna. Actually, however, the driver 
may often get out of the car without contracting the antenna. In such a 
case, the driver must enter again into the car for operating a switch so 
as to contract the antenna. For manually or automatically extending and 
contracting the antenna various proposals have been made. For example, 
where a multithread worm is used, it can be driven by manual operation and 
an electric motor. According to another proposal, a planet wheel mechanism 
is controlled by an electromagnet for extending and contracting the 
antenna. 
As above described, according to the prior art construction, an antenna 
operating member is made of a noncontractive linear synthetic resin wound 
about a rotary drum. Thus, the antenna is extended and contracted by the 
rotation of the drum through the antenna operating member. Accordingly, 
not only the drum diameter is increased but also the resistance to paying 
out and taking up of the antenna operating element having a relatively 
large resistance is increased. For this reason, the size of the antenna 
extending and contracting mechanism is determined by the diameter of the 
drum, meaning an increase in the capacity of the motor. The wire is payed 
out while being strongly urged against the inner surface of the drum or 
the surface of the winding groove (which is arcuate for receiving the wire 
having a circular cross-section). But the wire tends to slide along the 
inner surface of the drum or of the winding drum, while being inclined 
thereto. Thus, the pay out efficiency caused by a push force decreases 
substantially. Slipping of the wire while being urged against the inner 
surface of the drum or the surface of the winding groove means pushing out 
the wire from the rotatably mounted drum toward a stationary base member 
which causes the periphery of the drum to move away from the base member. 
According to operating conditions (especially, when the drum is not 
clutched off after it has reached the paying out limit or when the 
telescope type antenna is frozen in a cold season) the wire would be 
pushed in between the drum and the base member like a wedge, thus 
disenabling the rotation of the drum in either direction. Furthermore, the 
wire would be twisted helically in an opening through the antenna base 
cylinder, thus breaking the wire. 
In a construction utilizing a gear and if a rack and the operating member 
is payed out and taken up by the gear driven by a motor, the disadvantages 
described above can be obviated. However, in this construction, the 
mechanism for driving the gear with the motor becomes bulky. In a press 
molded rack or strip shaped rack formed with openings for engaging the 
gear, the longitudinal strength of the rack is small, thus failing to 
achieve a smooth extension and contraction of the antenna. Especially, a 
strip shaped rack has a tendency to bend thus failing to obtain optimum 
extension and contraction. In a construction where a plastic belt is 
clamped between opposing rollers, not only the construction becomes 
complicated but also the above described disadvantage of the strip shaped 
member can not be obviated. 
In the construction disclosed in Japanese Laid Open Patent Specification 
No. 90,951/1979, since a relatively long wire is payed out or taken up by 
the rotation of a pulley while being strongly urged against a stationary 
guide member, the friction between the wire and the guide member 
increases, thus disenabling smooth extension and contraction. Especially 
when the rear surface of the wire opposing the rack is made flat, these 
members contact with each other with a relatively large area thus 
increasing the friction therebetween. Especially in a strip formed with a 
rack or holes for engaging a gear, not only the number of the 
manufacturing steps increases but also sufficiently large longitudinal 
strength can not be obtained. For this reason, the cross-sectional area of 
the strip increases. 
The operating wire disclosed in Japanese Laid Open Utility Model 
Specification No. 31,044/1981 has substantially square cross-section. 
Although it can be neatly taken up in a drum, in the taken up state, the 
wire tends to bend in the circumferential direction of the drum so that 
the taken up state of the wire is not always stable. Accordingly, the push 
up force of the antenna and the extending and contracting characteristics 
are similar to a circular wire whereby smooth take up and miniaturization 
of the mechanism are difficult. 
Where a multithread worm is used for manually or automatically extending 
and contracting the antenna, the advantage of a low speed drive is 
decreased. Further, it is necessary to provide another speed reduction 
mechanism between the worm and the take up drum thereby increasing the 
capacity of the motor. When the motor operated system is operated 
manually, the motor operates as a generator so that it is necessary to 
provide a protective device for the source of the motor. A mechanism 
utilizing plat gears is required to be incorporated with a permanent 
magnet and a control switch for ON.multidot.OFF controlling the permanent 
magnet at a suitable timing. In each case, for preventing excessive load 
applied to the operating wire at the limits of extension and contraction 
of the antenna, it is necessary to provide a clutch mechanism for 
releasing the same when an overload condition occurs. As above explained, 
the construction of the prior art manual or motor operated antenna 
extending and contracting mechanism is complicated and its cost of 
manufacturing is high. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide an improved antenna 
extending and contracting mechanism utilizing a new type antenna operating 
wire capable of being helically or spirally wound on a take-up drum but 
having sufficient rigidity for transmitting a push out power to the 
antenna without bending. 
Another object of the present invention is to provide an improved antenna 
extending and contracting mechanism including a clutch enabling the 
antenna to be contracted and extended by an electric motor or by man 
power. 
Further scope of applicablity of the present invention will become apparent 
from the detailed description given hereinafter. However, it should be 
understood that the detailed description and specific examples, while 
indicating preferred embodiments of the invention, are given by way of 
illustration only, since various changes and modifications within the 
spirit and scope of the invention will become apparent to those skilled in 
the art from this detailed description. 
According to the present invention, there is provided an antenna extending 
and contracting mechanism of the type comprising a rotary drum for taking 
up and paying out a relatively rigid wire for extracting and contracting 
the antenna, an electric motor for driving the rotary drum, the antenna 
being made up of a plurality of telescoped antenna sections, an antenna 
base cylinder accommodating the sections when the antenna is contracted, a 
base member for supporting the rotary drum, the motor and the antenna, 
clutch means incorporated into a motion transmission system between the 
motor and the rotary drum, characterized in that the wire has a flat 
rectangular sectional configuration having a width of 1.5.about.2.2 times 
of a thickness, and one end of the wire is connected to the uppermost 
antenna section through the antenna base cylinder, and wherein guide means 
for receiving opposite ends of the wire in the width direction thereof is 
interposed between the antenna base cylinder and the rotary drum, the 
rotary drum being provided with means for edgewisely taking up the wire.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The present invention is characterized by an antenna operating wire 
utilized to extend and contract the antenna. As shown in the accompanying 
drawing, the wire 1 is made of such hard synthetic resin as polyacetal 
resin which does not extend or contract and becomes straight when 
released. The wire has a rectangular or similar cross-sectional 
configuration having a width W and a thickness t. The side surfaces 13 
between opposing flat surfaces 12 or 12a may be arcuate. 
The wires shown in FIGS. 1A and 1B have flat surfaces while the wires shown 
in FIGS. 1C and 1D have slightly convexed surfaces 12a. Irrespective of 
these configurations, the width of the wire should be large such that the 
arcuate side portions 13 will make intimate contacts with the inner 
surface of the base cylinder 7 of the antenna, or that the interfaces 
between the flat surfaces 12 or 12a and the arcuate side portions 13 would 
make line contacts against the inner surface of the antenna base cylinder 
in the axial direction of the wire 1. When the flat surfaces 12 are 
slightly convexed as shown by 12a in FIGS. 1C and 1D, extraction of the 
wire 1 becomes easy. However, the radius of the convexed surface should 
not be smaller than the radius of the inner surface of the base cylinder 
7. The flat surfaces 12 and the slightly convexed surfaces 12a are not 
required to be always smooth and may be slightly irregular. 
A plurality of telescoped tubular antenna sections 9a.about.9n are made of 
metals and have different diameters. When extended these sections 
constitute a multisection transmitting or receiving antenna. All of these 
antenna sections are accommodated in the antenna base cylinder 7 when they 
are contracted. Of course, the inner diameter of each antenna section is 
smaller than that of the antenna base cylinder 7. When the wire 1 
positioned in the antenna sections and the antenna base cylinder 7 as 
shown in FIG. 7B is subjected to a push out force, and as a result, when 
the wire flexes, the opposite sides of the wire would make line contacts 
with respective antenna sections. As shown in FIG. 7B, since the outer 
portions of such line contacts cooperate with the circular inner surface 
of the antenna base cylinder to form steeply inclined surfaces that 
prevent slip of the wire 1, sliding of the wire along the circular surface 
in any direction can be efficiently prevented. For this reason, even when 
a substantially large push out force is applied, the wire is held in a 
predetermined aligned position so that the push out force applied acts 
exclusively as upward push out force, thus ensuring accurate extension of 
the antenna. When applied with a push out force the conventional wire of a 
circular cross-sectional configuration will bend so that it makes a single 
line contact with the inner surface of the antenna base cylinder in a 
plane including the axis of the wire. Such single line contact requires 
stronger push out force, and a wire which bends in any arbitrary direction 
is caused to readily slide in the lateral direction by a force applied 
after the antenna has completely been extended, whereby the wire would 
bend wavy or spirally in the antenna base cylinder. Such bending of the 
wire in the antenna sections greatly reduces the push out force. Such 
decreased push out force merely acts as a bending force of the wire, thus 
degrading and breaking the wire. Moreover, it becomes difficult to obtain 
an accurate extended length proportional to the amount of rotation of a 
motor driven pay out drum. According to the present invention, since it is 
possible to efficiently prevent slip of the wire towards the lateral side 
of the contact point on the inner surface of the antenna base cylinder, a 
positive push out force can be obtained and the amount of extension 
becomes proportional to the amount of rotation of the motor or drum. 
The central portion 0 of the wire may take the form of a small opening 11 
as shown in FIGS. 1B and 1D. 
The antenna operating wire 1 is taken up or wound about a drum shaped 
take-up rotary drum 2. The wire can be taken up spirally as shown in FIG. 
3 or helically as shown in FIG. 2. The wire taken up in this manner is 
contained in a casing 3 shown in FIGS. 4 or 5 and the drum is rotated by 
an electric motor 4. The take-up drum 2 is secured coaxially with a motor 
driven worm wheel 5 and rotated integrally with the worm wheel 5 by the 
pressure applied by a clutch mechanism 6. As the pressure applied by the 
clutch mechanism is released, only the worm wheel 5 rotates. 
The wire 1 extends into the antenna base cylinder 7 and is connected to the 
uppermost one of the antenna sections having different diameters, so as to 
extend and contract the antenna sections by the forward and reverse 
rotation of the motor. Between the take-up drum 2 and the antenna base 
cylinder 7 is disposed a guide member which guides the wire into the 
take-up drum while spirally or helically bending the wire. As shown in 
FIG. 10, in this invention utilizing a flat wire 1, the guide member is 
provided with an inclined guide surface 31 on the side of the take-up drum 
2 and a groove 32 formed at the central portion of the inclined guide 
surface 31 for receiving one end of the flat wire 1. Since annular wire 
receiving groove 29 is provided for the inner periphery of the take-up 
drum 2 the groove 29 can receive the other end of the flat wire 1. The 
groove 29 has the same width as the groove 32. 
Until the leading end of the flat wire 1 which is guided to the inclined 
guide surface 31 through a perforation 30 at the bottom of the antenna 
base cylinder 7 reaches the inclined guide surface 31, the flat surfaces 
12 are not in any specific direction, but as the leading end of the wire 1 
is bent toward the wire receiving groove 29 by the inclined guide surface, 
due to the large resistance to the bending in the direction of the width 
of the wire, the bending of the wire is limited to its thickness direction 
so that one of the flat surfaces 12 is received in the receiving groove 29 
while the other is received in the receiving groove 32. Since the flat 
surfaces 12 are parallel to the periphery of the take-up drum 2, the above 
described guide operation makes easy winding of the wire. Since the wire 1 
is made of a polyacetal resin, the wire tends to slip on the inclined 
guide surface 31 and in the receiving groove 29 of the take-up drum 2 and 
as a result the receiving of the leading end of the wire can be smoothly 
effected. Once the leading end is correctly received, pay out and take up 
of the wire from and onto the rotary drum can be effected neatly and 
smoothly. In the embodiment shown in FIGS. 4 and 11, a ball 16 is secured 
to the leading end of the wire 1, and a circular enlarged groove 29a shown 
by dotted lines in FIG. 11 is formed at one portion of the receiving 
groove 29 to extend in the direction of the depth thereof, that is, the 
width direction of the take-up drum. At the time of inserting the leading 
end of the wire, the engaging member slides along the inclined guide 
surface 31 to reach the entrance of the circular enlarged groove 29a. 
During acceptance of the engaging member, the wire 1 is bent in its 
thickness direction, and moreover since one of the flat surfaces 12 
engages the opening end of the receiving groove of the take-up drum 2, the 
rolling of the engaging member becomes easy, whereby the receiving of the 
flat wire in the receiving grooves 29 and 32 becomes more smooth. 
Furthermore the ball 16 received in the enlarged groove 29a is pushed into 
a deep portion as the amount of the wire taken up increases, with the 
result that the entire length of the wire 1 can be neatly received in the 
receiving groove 29, as shown in FIG. 4. When the direction of rotation of 
the take-up drum 2 is reversed to pay out the wire 1, the ball 16 leaves 
the inclined guide surface and pulls the antenna into the cylinder 7. 
However, since the length of the wire is somewhat longer than the extended 
length of the antenna, even when the rotation of the drum 2 is stopped, 
when the antenna is perfectly extended, the leading end of the wire 1, 
that is ball 16, always maintains engagement with the circular enlarged 
groove 29a. 
We have found that a thickness to width ratio of 1.5.about.2.2 is 
advantageous for a flat operating wire made of a polyacetal resin or the 
like. When this ratio is less than 1.5, where the wire has an elliptical 
sectional configuration as shown in FIGS. 1C and 1D. The advantage of flat 
wire wherein the direction of bending is specified, can not be attained. 
On the other hand, where the thickness to width ratio exceeds 2.2, the 
wire become a strip or tape so that its antenna section push out force 
decreases. In other words, when applied with the push out force, the wire 
tends to bend into a complicated shape, thus losing the property of a 
rigid wire. Provision of an opening at the central portion of the wire 
does not affect the push out force of the wire so long as the radius of 
the opening is less than several % of the radius of the opening. 
FIGS. 7A, 7B, 8A, FIGS. 8B and 8C show the relationship between the 
cross-sectional configuration of the wire and the multi-section antenna. 
As is well known in the art, one end of wire 1 is connected to the 
uppermost section 9a of the antenna sections 9a, 9b . . . 9n. The 
uppermost section 9a is telescopely received in the second and succeeding 
sections. FIG. 8A shows a cross-sectional view utilizing a prior art or 
circular wire 1. In this case, the gap 19 between the wire 1 and the 
second antenna section 9b is relatively large, whereas in FIGS. 9B and 9C 
utilizing a flat wire 1 of the present invention, the gap 19a between the 
arcuate ends 13 of the wire and the second antenna section 9b is very 
small. Actually, the cross-antenna sectional area (or diameter) of the 
wire is limited by the inner diameter of the second antenna section 9b. In 
a multisection rod antenna now being used the inner diameter of the second 
antenna section 9b generally lies in a range of 4.3.about.4.5 mm so that 
the diameter or width of the wire 1 can not exceed the inner diameter of 
the second section. The load necessary for bending the flat wire of this 
invention having a width to thickness ratio of 1.5 in a direction parallel 
to flat surface amounts to about 3 times of the load necessary for bending 
a prior art round wire (shown in FIG. 8A) having a diameter of about 4 mm, 
made of polyacetal resin and bent with a radius of 4 cm. Such multiplying 
factor increases with the degree of flatness. As above described since the 
width of the wire is limited by the inner diameter of the second antenna 
section 9b, an increase in the ratio W/t means a decrease in t. A decrease 
in t decreases the strength of the wire. For this reason, it is impossible 
to make extremely large the ratio W/t so that about 2.2 is the upper 
limit. 
As shown in FIGS. 2.about.6, the flat wire of this invention is received 
between supporting walls 2b provided for the take-up drum 2. Since the 
wire 1 is flat, in each of the cases shown in FIGS. 2.about.6, the gap 
between adjacent supporting walls 2b is relatively narrow. At the time of 
paying out and taking up, the flat surfaces 12 engage the supporting walls 
2b, whereas at the time of pushing out the antenna sections, the flat 
surfaces engage the supporting walls on the radially inner wall. At the 
time of taking up for contracting the antenna, the flat surfaces engage 
the supporting walls on the radially inner side. The flat surfaces stably 
engages the supporting walls 2b and do not accompany slips along inclined 
surfaces which occurs when the wire has a circular cross-section. 
Consequently as shown in FIGS. 9A and 9B, even when the wire is urged 
against the outer supporting wall for producing a push out force 
(especially when the clutch is operated) the wire would not be clamped 
between the drum and base member as shown in FIG. 9A nor will the wire 
bends spirally in the antenna base cylinder. 
The clutch mechanism (shown in FIG. 5) incorporated between the worm wheel 
5 and the take-up drum 2 in the base member 3 comprises a clutch plate 69 
resiliently urged by a resilient member 96 against the take-up drum 2 
rotatably supported by the base member 3. A projection 69a on the 
periphery of the clutch plate 69 engages a projection provided for the 
take-up drum 23. The clutch plate 69 is mounted on a square shaft 55 of a 
worm wheel (not shown) meshing with worm 44 driven by an electric motor. 
Consequently, in a case wherein the take-up drum 2 is stopped when the 
shaft 55 of the worm wheel is rotated with a force larger than a 
predetermined clutch force, projection 69a disengages from projection 23, 
thus releasing the clutch. The square shaft 55 and a threaded shaft 55a 
integral therewith are formed with an inner bore to receive a mounting 
shaft of the base member 3 for mounting a cover member 9. 
A special clutch mechanism and elements associated therewith which are 
suitable for extending and contracting the antenna by utilizing the 
characteristics of the wire are shown in FIGS. 4, 11, 6 and 12. More 
particularly, a shaft 34 is secured to the central portion of the base 
portion 3 and the mounting seat 37 of the antenna base cylinder 7 and the 
mounting seat 36 of the motor 4 are provided for the upper portion of the 
base member 3, and a small worm wheel 35 meshing with the worm wheel 5 is 
secured to the lower surface of the mounting seat 36. A worm 44 driven by 
motor 4 meshes with the worm wheel 5. Where a small motor 4a is secured to 
the mounting seat 36 instead of motor 4, a worm 44a driven by the small 
motor 4a drives the worm wheel 5 via a small worm wheel 35. More 
particularly, where motor 4 is used as shown in FIG. 12A, and where a 
small motor 4a is used as shown in FIG. 12B, the worm wheel 5 can be 
driven efficiently. In the antenna extending and contracting mechanism 
constituted by the base member 3, the take-up drum 2 and the worm wheel 5 
which are made of a synthetic resin, the weight of the motor 4 is the 
maximum so that when a small motor 4a is used the weight of the mechanism 
can be reduced substantially. In recent years, it is strongly desired to 
decrease the weight and size of the parts of motor cars. Thus the 
mechanism just described can meet these requirements. The clutch mechanism 
utilized in this invention will now be described with reference to FIGS. 4 
and 11. Thus the mounting shaft 34 is received in an opening 50 provided 
for the worm wheel 5 and the shaft 51 thereof. Engaging surfaces are 
formed on one end of shaft 51 for engaging with the engaging surfaces 82 
provided for an opening 80 of a rotating member 8 (to be described later) 
so as to be slidable in the axial direction but to rotate integrally. The 
shaft opening 20 of the take-up drum 2 is fitted on the base end of the 
shaft 51. The rotary member 8 and the clutch member 6 are amounted on the 
engaging surfaces 52 in a chamber 27 on the inside of the receiving groove 
29 of the take-up drum thus fitted. Thus, a circular shaft openings 60 are 
provided for the rectangular clutch member 6. An opening 61 for receiving 
the rotary member 8 is defined between opposing sides of the clutch member 
6. The substantially rectangular rotary member 8 is assembled to cross the 
clutch member 6. The engaging surfaces 82 of an opening 80 for receiving 
the rotary member 8 are caused to engage the engaging surfaces 52 so as to 
transmit the torque of the worm wheel 5 to the rotary member 8. Valley 
shaped cams 84 are formed at the centers of the side surfaces of the 
rotary member 8 and inclined engaging members 85 adapted to engage 
projections 66 on the upper and lower sides of the shaft opening 60 of the 
clutch member 6 are formed on both sides of the valley shaped cams 84. The 
shorter end surfaces of the clutch member 6 are provided with opposing 
openings 62 in which a pair of engaging members 64 and 65 interconnected 
through a coil spring 63 are fitted respectively. The inner members 65 are 
received in the valley shaped cams 84, while the outer members 64 are 
caused to engage and disengage a plurality of recesses formed on the side 
surface of the chamber 27 of the drum. 
A washer 14 and a E ring 15 are mounted on the shaft 34 of the base member 
3 mounted with the worm wheel 5, the take-up drum 2, the clutch member 6 
and the rotary member 8 and a leaf spring 68 is caused to engage inclined 
portions 67 formed on the opposite surfaces of the clutch member 6. A 
frictional force of the leaf spring 68 created by a nut 33 (see FIG. 4) 
threaded on the shaft 34 is applied between the clutch member 6 and the 
take-up drum 2 so as to make different the rotations of the rotary member 
5 and the clutch member 6. 
The clutch mechanism described above can also be applied to a take-up drum 
which spirally takes up the wire as shown in FIGS. 3 and 6. More 
particularly, a spiral wire receiving groove 24 is formed on one surface 
of a plate shaped rotary member 2 and an annular projection 28 is formed 
on the other side of the rotary member 2 to define a chamber 27 for 
receiving the clutch member 6, and the rotary member 8 in the same manner 
as that shown in FIG. 4. A partition plate 26 having a center opening 26a 
for passing the shaft is disposed between the base member 3 and the 
take-up drum 2 at the opening of the spiral wire receiving groove 24. The 
partition plate 26 is formed with a radially extending wire admitting 
notch 25 over the entire range in which the wire receiving slot 24 is 
formed. Thus, one end of wire 1 led from the antenna base cylinder 7 is 
connected to the drum 2 through the notch 25. 
A switch mechanism may be provided for automatically controlling the motor. 
Such switch mechanism is designated by 90 in FIG. 11 and provided with a 
rotary member 93 in the form of a gear 93 that engages projections 53 on 
the rear surface of the worm wheel 5. As the gear shaped rotary member 93 
intermittently rotates by engaging the projections 53 so as to transmit 
the rotation of the worm wheel 5 imparted by motor 4 to the swtich 
mechanism 90 for ON.multidot.OFF controlling the stop signal of the motor 
4. Such mechanism can be used for a case wherein the antenna is extended 
and contracted by the operation of a car switch (that is an engine switch) 
or a radio switch and the motor is stopped at the limits of extension and 
contraction of the antenna. 
In the embodiment shown in FIGS. 4 and 11, the construction of the 
extending and contracting mechanism including the motor can be made 
compact, the base member thereof being shown in FIG. 10. According to this 
invention, since a flat wire 1 is used, the diameter of the take-up drum 2 
can be made small. Hence the diameters of the base member 3 and the cover 
10 can also be reduced. The motor mounting seat 36 formed at one side of 
the upper portion of the base member 3 is inclined toward the other side 
of the base member so that the motor 4 or 4a mounted on such mounting seat 
36 inclines towards the antenna base cylinder as shown in FIG. 12, whereby 
the motor 4 is mounted in the reduced diameter range of the base member 3. 
An inner space 38 in the mounting space 36 can be formed by stamping the 
base portion 3 formed integrally at right angles with respect to a 
reference surface of the base member 3, for example the mounting surface 
37 of the antenna base cylinder. Since the motor 4 is positioned in a 
range of the diameter of the reduced diameter base member 3, the 
construction of the automatic antenna extending and contracting mechanism 
can be made to be compact, thereby facilitating the mounting of the 
mechanism on a car, which also decreases the volume of the packed 
mechanism. Generally stated, in the mechanism of this type, a portion 
having a length nearly equal to the radius of the motor projects beyond 
the range of the diameter of the base member 3. For example, in FIG. 12A 
when worm 44 is caused to engage worm wheel 5 on the outside thereof and 
in a vertical position, a portion of the motor 4 nearly equal to the 
radius thereof will project to the outside of the base portion. 
The clutch mechanism shown in FIGS. 4, 11 and 6 operates as follows. In a 
stationary state in which the torque of the worm is not transmitted to the 
worm wheel 5, its shaft 51, and the rotary member 8, the engaging member 
65 is positioned at an intermediate portion of the valley shaped cam 84. 
Under this state, the coil spring 63 is not compressed to any appreciable 
extent so that the engaging member 64 is disengaged from the recess 21 of 
take-up drum 2 as shown by a portion above the shaft 34 shown in FIG. 4. 
Hence, in this condition, the drum 2 can rotate without accompanying the 
clutch member 6 and the rotary member 8. Even when the recess 21 and the 
opening 62 are located on the lower side so that the engaging member 64 is 
received in the recess 21, as the take-up drum 2 rotates the engaging 
member 24 is pushed out of the recess 21 to reach in the range of the 
clutch member 6, thus permitting the take-up drum 2 to rotate. In other 
words, when the extended antenna sections 9a.about.9n are manually 
contracted, the wire 1 is pushed into the take-up drum 2 to rotate the 
drum. In this manner, when the antenna is manually contracted, the wire 
can be wound about the drum. In the same manner, when the antenna sections 
are manually extended, the take-up drum 2 is rotated. 
In the case of motor drive, where the torque of the worm 44 is transmitted 
to the rotary member 8 via worm wheel 5, and shaft 51 depending upon 
whether the motor is driven in the forward direction or reverse direction, 
either one of the inclined portions 85 rotates in a direction to engage 
either one of the projections thereby rotating the clutch member 6. This 
rotation pushes upwardly the engaging member 65 away from the valley 
shaped cam 84 to compress the spring 63. As a consequence, the engaging 
member 64 is pushed into the recess 21 so as to rotate the drum 2 together 
with the clutch member 8. Thus, the torque of the motor 4 is positively 
transmitted to the take-up drum 2 for automatically contracting the 
antenna. 
The operation of the clutch at the time of contracting the antenna with a 
motor is as follows: 
When the motor is driven while the member 64 shown at a position below 
shaft 34 in FIG. 4 is being engaged, as a load of a predetermined value, 
for example 5 Kg, is applied to the motor at the limit of extension or 
contraction or at any time, the member 64 will further compress the spring 
63 to disengage the member 65 from the recess 21. Thus the motor continues 
to rotate with the clutch disengaged. 
With the clutch mechanism shown in FIGS. 4, 11 and 6, it is possible to 
readily release the clutch for facilitating manual extension and 
contraction at the beginning thereof, the clutch mechanism being 
indispensable for stopping the take-up drum at the time of automatically 
extending and contracting the antenna. This climinates the provision of an 
independent clutch mechanism for manual operation of the antenna, thus 
simplifying the construction. For example, at a time of washing a car, 
while preventing the washing water from entering into the engine room by 
operating a fan by the continued running of the car engine, the extended 
antenna can be manually contracted for facilitating the car washing. Of 
course, the driver can get out of the car to contract the antenna. 
The engaging member 64 is always pressed into the recess 21 by spring 63. 
When this engagement is released manually, the antenna can be extended or 
contracted. Guide means for taking up the wire between the antenna base 
cylinder and the take-up drum with the thickness direction of the wire 
oriented in the radial direction of the take-up drum not only provides an 
advantageous guide function to the wire at the time of extracting the 
antenna but also a desirable contact resistance when the extended antenna 
tends to contract due to the vibration of the car. In other words, the 
surface of the bent or inclined guide means produces a friction for the 
wire, thereby preventing contraction of the extended antenna. 
Above described connection between the upper end of the wire 1 and the 
uppermost antenna section 9a permits free exchange of the antenna together 
with the engagement of the spherical portion 16 at the lower end of the 
wire 1 (see FIG. 11) with circular enlarged groove 38 as well as the 
sliding of the wire along the groove 38. Of course, the antenna sections 
9a.about.9n can be exchanged in the same manner. 
Where the switch mechanism 90 described above is used, the antenna can be 
pushed out without causing the wire 1 to twist helically in the antenna 
base cylinder 7, so that the antenna sections 9a.about.9n can be extracted 
and contracted in proportion to the amount of rotation of the worm wheel 5 
or motor 4, thereby decreasing the load thereof. Usually, the switch is 
opened and the clutch is released to stop the motor when the antenna has 
been completely contracted or extended so that it has been prohibited to 
release the clutch or to open the switch before complete extension of the 
antenna because there is a large probability that the motor is stopped 
before complete extension of the antenna. Under this condition, the wire 1 
is twisted helically. In contrast, where the clutch is released or the 
switch is opened to stop the motor after the antenna has been completely 
extended or contracted the load of the motor after complete extension or 
contraction would become extremely high. This means that the switch is 
opened under the maximum load after releasing the clutch so that the wire, 
the mechanism for extending and contracting the antenna and the motor 
would be subjected to a undue force, thus resulting in wear. According to 
this invention in which the amount of rotation of the motor or the worm 
wheel is directly proportional to the amount of extension and contraction 
of the antenna so that the tendency of twisting the wire in the antenna 
base cylinder can be prevented and it is possible to forecast the time of 
complete extension and contraction based on the amount of rotation so as 
to open the switch before the complete extension, thereby effecting 
perfect extension or contraction by the inertia of rotation of the motor, 
worm wheel and the take-up drum. With this measure, undue force and the 
wear of the mechanism can be avoided after the antenna has been completely 
extended or contracted. Since the invention enables manual and automatic 
operations, especially at the time of manually extending the antenna, the 
antenna can readily be extended by inserting a key into knob at the top of 
the uppermost antenna section. 
In this invention, since a flat wire is used for extending and contracting 
the antenna, the flexibility of the wire in a direction perpendicular to 
the flat surface of the wire can be decreased and the take-up property of 
the flat wire can be improved. Accordingly, it is possible to smoothly 
take-up and pay out the wire by using a relatively small and compact 
take-up drum. The flat wire can be stably supported by the supporting 
walls provided for the drum. Moreover, the wire is maintained in a 
straight condition in the antenna base cylinder so that the wire can 
extend and contract the antenna without bending. Accordingly, stable and 
strong extending and contracting forces can be applied. Moreover any gear 
or geared pulley or the like driven by the motor is not necessary for 
operating the wire. Further a large wire guide is also unnecessary, thus 
simplifying the construction. In spite of the fact that the wire has a 
substantially rectangular cross-section it manifests a small resistance to 
the pay out and take-up motions, thus decreasing the necessary driving 
force. 
According to this invention, a flat wire is used, a rotating member driven 
by a motor is contained in a clutch member concentric with a wire take-up 
drum, and a cam is provided for the rotary member for causing an engaging 
member provided for the clutch member to engage and disengage a recess 
formed on the inner surface of the rotary member, so that at the time of 
extending and contracting the cam causes the engaging member to fit into 
the recess for engaging the clutch member so as to obtain automation 
extending and contracting operations. At the time of manually extending 
and contracting the antenna, the wire disengages the clutch so that 
transfer can be made readily between the automatic and manual operations 
without using any special transfer mechanism, thereby simplifying the 
construction.