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EP 0 125 085 B1 |
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EUROPEAN PATENT SPECIFICATION |
(45) |
Mention of the grant of the patent: |
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01.07.1987 Bulletin 1987/27 |
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Date of filing: 30.04.1984 |
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Variable inductor mechanism
Vorrichtung veränderlicher Induktivität
Dispositif à inductance variable
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Designated Contracting States: |
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BE DE FR GB IT NL SE |
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Priority: |
03.05.1983 GB 8312073
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Date of publication of application: |
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14.11.1984 Bulletin 1984/46 |
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Applicant: SHAYE COMMUNICATIONS LIMITED |
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Winchester,
Hampshire SO23 7BH (GB) |
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Inventors: |
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- Pye, Michael Richard
Winchester
Hampshire SO22 4NP (GB)
- Beesley, Graham Edgar
Sparsholt
Winchester
Hampshire SO21 2NJ (GB)
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(74) |
Representative: Boydell, John Christopher et al |
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Stevens, Hewlett & Perkins
1 Serjeants' Inn
Fleet Street London EC4Y 1LL London EC4Y 1LL (GB) |
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Note: Within nine months from the publication of the mention of the grant of the European
patent, any person may give notice to the European Patent Office of opposition to
the European patent
granted. Notice of opposition shall be filed in a written reasoned statement. It shall
not be deemed to
have been filed until the opposition fee has been paid. (Art. 99(1) European Patent
Convention).
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[0001] This invention relates to a variable inductor mechanism and in particular to a tuning
mechanism for tuning a receiver, such as a radio receiver. The mechanism is especially
suited to miniaturisation and has been particularly designed for tuning a wrist mounted
radio. It will be appreciated, however, that the invention is not limited to such
a use, and could, for example, be used for any of the normal inductance uses, such
as for the adjustment or tuning of audio signals, filters and the like.
[0002] It is a well known fact that the resonant frequency of an UC tuned circuit, such
as that used for tuning a radio receiver, is altered by varying the inductance of
a coil or varying capacitance of a capacitor, which forms part of a tuning circuit.
The present invention is particularly concerned with altering the inductance of a
coil.
[0003] Various proposals have been put forward for varying the inductance of coils using
a disc rotatable in a plane extending at right angles to the axis of the coil. For
example, in DE-C-669078 a coil has its inductance varied by means of a metal disc
of variable thickness which is rotatable about a central axis by means of a control
knob. Hence, the inductance of the coil is influenced in dependence upon the transverse
position of the influencing means (the metal disc) relative to the coil axis. The
disc is guided by plates extending across the end of the coil and the whole mechanism
is so large that it is capable of achieving changes in inductance in the range of
5-36 Henrys. In US-A-3155931, the rate of variation of the inductance of the coil
is dependent on the distance and thickness of a rotatable disc from the coil axis.
GB-A-1097303 also discloses a device for varying the mutual coupling between first
and second coils by passing a screen member made of a material of high conductivity
between the two coils.
[0004] In the above three prior art constructions, the discs or screen member have a high
mass and moment of inertia and are not suitable for miniaturisation. The present invention
seeks to provide a variable inductor mechanism which is compact and in which the adjusting
means has negligible mass and moment of inertia and lends itself to miniaturisation.
[0005] According to the present invention, we provide a variable inductor mechanism comprising
a coil and influencing means to influence the inductance of the coil, in dependence
on the transverse position of the influencing means relative to the coil axis, characterised
in that the influencing means is supported on or forms part of a flexible tape movable
longitudinally in a direction generally transverse to the axis of the coil.
[0006] Preferably, the influencing means is movable along a path which intersects the axis
of the coil at right angles.
[0007] According to one embodiment of the invention, the influencing means is applied to
selected parts of a surface of the tape in such a way that its influence on the coil
will vary in dependence upon which portion of the tape is aligned with the longitudinal
axis of the coil.
[0008] Preferably, the tape is in the form of an endless tape loop. While it is envisaged
that the tape may itself be formed entirely of a conductive material, it is preferred
that it is made of non-conductive material with a conductive layer on one of its surfaces.
[0009] In a preferred construction, the endless tape loop is entrained around and engages
with a drive sprocket and passes around a smooth roller which is sprung so as to act
as an idler and keep the tape in tension.
[0010] Preferably, the tape loop is formed of a thin polyester or polyimide material (10-20
pm), and the conductive layer is formed of copper or another metal etched onto a surface
of the tape,. or any other substance capable of varying the' inductance of the coil,
and the conductive layer is wedge shaped, with the longitudinal axis of the wedge
extending along the axis of the tape, so that as the tape is advanced past the longitudinal
axis of the coil, the width of the conductive layer will increase or decrease uniformly,
thus varying the inductance or coupled inductance of the coil.
[0011] In the preferred arrangement, the physical position of the sprocket is such that
the tape always runs over the smooth surface of the coil former and thus remains at
a fixed distance from the coil.
[0012] Preferably, a tuning scale is also printed onto the tape, and the arrangement may
be such that as the lower run of the tape loop passes across the coil axis, the scale
will be visible and move along the upper run of the loop. The mechanism is particularly
suited for use as a tuning mechanism for a miniature radio receiver which can be worn
on a person's wrist, and the scale may therefore be located beneath a window in a
casing, and the drive sprocket may be connected to a control knob located on the outside
of the casing.
[0013] Although described for use with a receiver, it should be noted that the mechanism
could alternatively be used to tune a transmitter, and for many other inductance uses.
[0014] Backlash in the mechanism is reduced to a minimum by providing domed sprocket teeth
on the sprocket, which engage with an interference fit in holes in the tape.
[0015] It will thus be appreciated that if the coil is connected to other components of
a tuning circuit, e.g. of a radio receiver, which may be located around the coil beneath
the influencing means, the frequency characteristic will be governed by the "shape"
of that portion of the "conductor layer" which intersects the flux lines of the coil.
[0016] The tape loop has very low mechanical inertia, resulting in a high degree of immunity
to mechanical vibrations. Also, by printing the tuning scale on the tape, maximum
use is made of the tape, and additional moving parts are not required, and an integral
tuning mechanism and frequency display is provided with a long length tuning scale.
[0017] It will be appreciated that the influence of the influencing means on the inductance
of the coil can be varied by providing different patterns of the "conductor layer".
While the standard configuration would normally have a wedge shaped pattern, it would
be possible to have two wedge shaped, generally parallel spaced wedge portions. This
has the advantage that tolerances to displacement of the influencing means perpendicular
to the longitudinal axis of the wedge can be reduced. Alternatively, the "conductor
layer", instead of being a continuous wedge, could be made up of a plurality of spaced
"conductor" segments, dots, bars, etc., of different size, width, depth, spacing,
density, etc.
[0018] It should also be borne in mind that the "conductor layer" need not just be a surface
layer on the tape. It could comprise a part of the tape extending throughout the total
width of the sheet- like material of the tape. It is even envisaged that the whole
tape could be metallic, and of varying width and/or thickness, thus having, over any
chosen area, a different inductance or coupling effect which would influence the inductance
of the coil as it was moved past the coil axis.
[0019] It should also be realised that the tape need not be in a closed loop, and it is
envisaged that other configurations are possible.
[0020] A tuning mechanism in accordance with the present invention is now described by way
of example, with reference to the accompanying drawings, in which:-
FIGURE 1 is a partly schematic side elevation of a preferred construction;
FIGURE 2 is a plan view of part of the tape (represented by arrows A-A in Figure 1)
used in the mechanism of Figure 1;
FIGURE 3 is a schematic side elevation of a drive sprocket;
FIGURES 4a-4e show various alternative conductor patterns applicable to the tape;
FIGURE 5 is a perspective view of a modified tuning mechanism' for incorporation in
a wrist watch; and
FIGURE 6 is a perspective view of the body of a wrist watch incorporating the mechanism
of Figure 5.
[0021] Referring to Figures 1 and 2 of the drawings, the tuning mechanism comprises a coil
1 mounted on a substrate 3. The coil is connected in known manner to other components
of a tuning circuit for a radio receiver, and for a miniature receiver for which the
present invention is designed (but this is not its only use), the other circuit components
(not shown) are sufficiently small to be mounted on the substrate 3 to either side
of the coil 1. The other main component of the tuning mechanism is a coil inductance
influencing means, in the form of an endless loop of tape 5, entrained around a drive
sprocket 7 and an idler roller 9, each of which is supported in known manner for rotation
about a suitable axis extending generally parallel to the substrate 3. The roller
9 is kept in place by a tension spring 11 which may also be used to tension the tape
loop 5. The drive sprocket 7 may be replaced by a friction roller drive and instead
of providing an idler roller 9, a fixed rolling surface such as a shaft, could be
provided. As can be seen from Figure 1, the lower run of the tape 5 runs across the
top of the coil 1, and although not essential, in the illustrated construction, lies
generally in a plane extending normal to the longitudinal axis of the coil 1.
[0022] The tape 5 is preferably formed of a thin (10-20 pm) polyester or polyimide material,
such as Du Pont's KAPTON, and an essential requirement is that at least the part of
the tape or a surface layer thereon which moves across the end of the coil (or in
a generally transverse direction adjacent the end) is of a conductive nature, i.e.
acts as a conductor. One preferred construction is illustrated in Figure 2, with the
polyester or polyimide portion indicated at 13, and a metallic portion shown at 15.
The metallic portion could be a surface layer adhered or deposited on the portion
13, or it could be, e.g. copper or another good conductor etched into portion 13.
Other constructions are possible; for example, the whole tape could be metallic.
[0023] An essential requirement is that the coupled inductance of the tape should vary over
its surface area. In the preferred construction, this is achieved by the metallic
portion 15 being of a particular pattern, in this case of a uniformly increasing width
from one end to the other. It will thus be appreciated that the lower run of the tape
can be divided up into a very large number of regions, five of which B, C, D, E and
F are notionally illustrated in Figure 2. By rotating the sprocket 7 and moving the
tape across the end of the coil 1, any one of these regions will overlie the end of
the coil, and the area of the metallic, i.e. conductive, tape portion 15 (the "conductor
layer") will be considerably greater when region B overlies the coil end than the
area when region F overlies the end of the coil 1. This "conductor layer" portion,
depending on its area, will thus intersect lines of flux emanating from the coil 1
when this is connected into the tuning circuit and the resonant frequency of the tuning
circuit will thus be altered in dependence on the coupled inductance of the portion
of the "conductor layer" part of the tape 5 overlying the coil.
[0024] In order to advance the tape 5 past the end of the coil 1, it is necessary to rotate
sprocket 7. This can be achieved by keying the sprocket on a shaft 8 to which a control
knob (not shown) may be fixed. Rotation of the knob will rotate the shaft 8 (see Figures
5 and 6).
[0025] It is preferred that at least one row of equally spaced holes 19 is formed in tape
5, which mesh with domed sprocket teeth 21 (see Figure 3) in the drive sprocket 7.
In this way, the whole tuner mechanism will have a very low backlash, and of course
very low mechanical inertia, resulting in a high degree of immunity to mechanical
vibrations.
[0026] A further important feature of the invention is the provision of a tuning scale 10
on the tape 5 (see Figures 5 and 6). In the illustrated construction, the scale 10
is on the upper face of the upper run 12 of the loop, and when the whole mechanism
is surrounded by a casing 14, the shaft 8 for the tuning knob projects through an
aperture in a side wall 16 of the casing 14, and a window 18, which may have a hairline
reference line, is provided in the top wall 20 of the casing 14, through which the
tuning scale 10 can be read, as it is advanced, by rotation of the shaft 8, past the
window 18.
[0027] As an alternative to using a tape loop or a disc, a finite length of the tape movable
from one "spool" to another "spool" could be used.
[0028] It will thus be appreciated that the frequency characteristics of a tuning circuit
is influenced by the area (shape) of the portion of the "conductor layer" on the influencing
means, i.e. tape carrier, overlying the coil 1. The whole mechanism has a minimum
number of moving parts with the tuner scale 10 integral with the influencing means.
As a result, the mechanism is very compact, has a minimum of mechanical inertia and
hence has a high degree of immunity to vibration, which is a big advantage since,
if it is used as a miniature radio tuner, it allows a moving coil loudspeaker to be
located very close to the mechanism. Also, there is no backlash in the tuning mechanism.
[0029] Although suited to any type of inductance tuning mechanism or tuner, the invention
has been designed specifically for a miniature radio receiver, and it is envisaged
that the coil 1 need only be about 4 mm in diameter and 2 mm in height, with the total
length about 16 mm and width about 8 mm, and no more than about 4 mm high.
[0030] It is envisaged that the initial inductance of the coil 1 could be adjusted by providing
a metal ring around the lower end of the coil. Furthermore, the spacing of the influencing
means from the coil will affect the coupled inductance of the coil, as will the permeability
of the coil core. Likewise, the range of coil inductance and absolute values can be
affected by additional coils, rings and cores, in accordance with known practice.
The coil core could, for example, be a ferrite/iron core, and the coil is not limited
to a small length/diameter ratio.
[0031] It will of course be appreciated that the wedge shape of the "conductor layers" 15
shown in Figure 2 could be altered as desired to vary the inductance of coil 1. The
preferred construction, together with four of many possible alternative shapes or
patterns are illustrated in Figure 4, where like or similar parts are identified by
the same reference numerals. The second construction comprises two split wedge shapes,
and instead of having the "conductor layer(s)" 15 passing centrally over the coil
axis, has the layers 15 passing off centre, and this means that if the influencing
means becomes laterally offset relative to the coil axis, although one of the wedge
portions 15 will move away from the coil axis, it will be compensated for by the other
portion 15 moving nearer the coil axis. It is of course also possible to vary the
distance of the influencing means from the coil as the former is moved transversely
across the coil axis.
[0032] It will be appreciated that if desired, more than one coil 1 may be provided, in
which case, the "conductor layer" of the influencing means could be duplicated so
that there is a portion associated with each coil. Hence, the coils can be ganged
in a tuning circuit and it is even possible to arrange for the inductance of one coil
to increase while the other decreases, by using a single influencing means as described
with two "conductor layers". It is even envisaged that a split coil, partly above
and partly below the influencing means, could be used, or that two coils could be
used which are antiphase connected.
[0033] The essence of the invention is to provide a substantially flat "conductor layer"
which either forms or is mounted on a surface of a tape, which can be moved generally
transverse to the axis of a coil, and which acts as an influencing means to vary the
inductance or coupled inductance of the coil. The "conductor layer" is any substance
capable of varying the inductance of the coil, and by varying the "intensity" of this
layer, e.g. over the surface of the tape, the transverse location of the "conductor
layer" relative to the coil axis will influence the inductance of the coil, which
forms part of an inductance tuning circuit. The "intensity" can be changed by variations
in shape, size, density, spacing of the said substance, e.g. by giving it a wedge
shape, or providing it in the form of dots or bars of different size, shape, spacing,
density, or any combination thereof. Of course, at any one location of the influencing
means, only a relatively small part of the "conductor layer" is effective in influencing
the inductance of the coil.
[0034] Instead of providing a drive sprocket for the tape loop, a drive shaft with a suitable
operating knob at one end may be used to impart drive by means of friction to the
loop. For this purpose a sleeve of resinous material may be forced onto a central
region of the drive shaft and after the loop has been mounted on the drive shaft and
a further idler shaft, the shafts may be mounted in a resiliently deformable frame,
one of the shafts being located between suitable forked bearings extending outwardly
from one end of the frame and the other shaft being located between similar bearings
at the other end of the frame but projecting at right angles to the first mentioned
forks with the second shaft being located within the forks by means of a generally
over-centre action.
1. A variable inductor mechanism comprising a coil (1) and influencing means (15)
to influence the inductance of the coil (1), in dependence on the transverse position
of the influencing means relative to the coil axis, characterised in that the influencing
means (15) is supported on or forms part of a flexible tape (5) movable longitudinally
in a direction generally transverse to the axis of the coil (1).
2. A mechanism according to claim 1 characterised in that the influencing means (15)
is movable along a path which intersects the axis of the coil (1) generally at right
angles.
3. A mechanism according to claim 1 or 2 characterised in that the influencing means
(15) is laminated onto a surface of the tape (5).
4. A mechanism according to claim 3 characterised in that the influencing means (15)
is applied to selected parts of a surface of the tape (5) in such a way that its influence
on the coil (1) will vary in dependence upon which portion of the tape (5) is aligned
with the longitudinal axis of the coil.
5. A mechanism according to claim 1 or 2 characterised in that the influencing means
(15) is self-supporting.
6. A mechanism according to any one of the preceding claims characterised in that
the influencing means (15) is formed entirely of a conductive material, or of any
other material capable of varying the inductance of the coil.
7. A mechanism according to any one of the preceding claims characterised in that
the tape (5) is in the form of an endless tape loop.
8. A mechanism according to claim 7 characterised in that the endless tape loop (5)
is entrained around and engages with a drive sprocket (7), and passes around a tensioning
roller (9).
9. A mechanism according to claim 7 or 8 when dependent on claim 3 or 4 characterised
in that the tape loop (5) is formed of a thin polyester or polyimide material and
has a conductor layer (15) formed either of copper or another metal or of any other
substance capable of varying the inductance of the coil (1) etched or otherwise deposited
onto a surface of the tape (5).
10. A mechanism according to claim 9 characterised in that the conductor layer (15)
is wedge shaped, with the longitudinal axis of the wedge extending along the axis
of the tape (5), so that as the tape is advanced past the longitudinal axis of the
coil (1), the width of the conductor layer will increase or decrease, thus varying
the inductance of the coil (1).
11. A mechanism according to claims 7, 8, 9 or 10 characterised in that a tuning scale
(10) is printed onto the tape (5), and the arrangement is such that as the lower run
of the tape loop (15) passes across the coil axis, the scale (10) will be visible
and move along the upper run of the loop (15).
12. A mechanism according to claim 11 characterised in that the mechanism is incorporated
in a miniature radio receiver which can be worn on a person's wrist, and wherein the
scale (10) is located beneath a window (18) in a casing (14), and the drive sprocket
(7) is mounted on a drive shaft (8) projecting from a side wall (16) of the casing
(14).
13. A mechanism according to any one of claims 9-12 characterised in that domed sprocket
teeth (21) are provided on the drive sprocket (7), which engage with an interference
fit in holes in the tape (5).
14. A mechanism according to any one of the preceding claims 1-13 characterised in
that the influencing means (15) is generally wedge shaped (Figures 2 and 4).
15. A mechanism according to any one of claims 1-13 characterised in that the influencing
means (15) comprises two generally parallel spaced wedge shaped portions (15) (Figure
4b).
16. A mechanism according to any one of claims 1-13 characterised in that the influencing
means (15) is made up of a plurality of spaced segments of different width, size,
spacing, density or the like (Figures 4c, 4d and 4e).
17. A miniature wrist watch radio including a variable inductor mechanism (Figure
5) for tuning the radio, which mechanism is as claimed in any one of the preceding
claims, and is located in a casing (14) (Figure 6).
1. Variabler Induktormechanismus mit einer Spule (1) und Beeinflussungsmitteln (15)
zum Beeinflussen der Induktanz der Spule (1) in Abhängigkeit von der Querlage der
Beeinflussungsmittel relativ zur Spulenachse, dadurch gekennzeichnet, dass die Beeinflussungsmittel
(15) sich auf ein flexibles Band (5) abstützen oder ein Teil eines flexiblen Bandes
(5) bilden, das in Richtung im wesentlichen quer zur Achse der Spule (1) längsbeweglich
ist.
2. Mechanismus nach Anspruch 1, dadurch gekennzeichnet, dass die Beeinflussungsmittel
(15) entlang einem Weg bewegbar sind, der die Achse der Spule (1) im wesentlichen
im rechten Winkel schneidet.
3. Mechanismus nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass die Beeinflussungsmittel
(15) auf einer Oberfläche des Bandes (5) laminiert sind.
4. Mechanismus nach Anspruch 3, dadurch gekennzeichnet, dass die Beeinflussungsmittel
(15) auf ausgewählten Teilen einer Oberfläche des Bandes (5) derart aufgebracht sind,
dass deren Einfluss auf die Spule (1) sich in Abhängigkeit davon ändert, welcher Abschnitt
des Bandes (5) mit der Längsachse der Spule ausgerichtet ist.
5. Mechanismus nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass die Beeinflussungsmittel
(15) selbsttragend sind.
6. Mechanismus nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass
die Beeinflussungsmittel (15) vollständig von einem leitfähigen Material gebildet
sind oder von irgendeinem anderen Material, durch das die Induktanz der Spule geändert
werden kann.
7. Mechanismus nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass
das Band (5) die Form eines Endlosbandes hat.
8. Mechanismus nach Anspruch 7, dadurch gekennzeichnet, dass das Endlosband (5) um
ein Antriebsrad (7) und eine Spannwalze (9) geführt ist.
9. Mechanismus nach Anspruch 7 oder 8, wenn rückbezogen auf Anspruch 3 oder 4, dadurch
gekennzeichnet, dass das Endlosband aus einem dünnen Polyester- oder Polyimidmaterial
hergestellt ist und eine Leitschicht (15) aufweist, die aus Kupfer oder einem anderen
geeigneten Material besteht, das die Induktanz der Spule (1) ändern kann, wobei die
Schicht auf die Oberfläche des Bandes (5) geätzt oder anderweitig abgelagert ist.
10. Mechanismus nach Anspruch 9, dadurch gekennzeichnet, dass die Leitschicht (15)
keilförmig ausgebildet ist und die Längsachse des Keiles entlang der Achse des Bandes
(5) verläuft, so dass das Band vorbei an der Längsachse der Spule (1) vorbewegt wird
und dabei die Breite der Leitschicht zunimmt oder abnimmt, wodurch die Induktanz der
Spule (1) veränderbar ist.
11. Mechanismus nach Anspruch 7, 8, 9 oder 10, dadurch gekennzeichnet, dass eine Abstimmskala
(10) auf das Band (5) gedruckt ist und dass die Anordnung derart ist, dass das untere
Trum des Endlosbandes (5) über die Spulenachse verläuft und dass die Skala (10) sichtbar
ist und sich entlang dem oberen Trum des Endlosbandes (5) bewegt.
12. Mechanismus nach Anspruch 11, dadurch gekennzeichnet, dass der Mechanismus in
einem Miniaturradioempfänger untergebracht ist, der am Handgelenk einer Person getragen
werden kann, und dass die Skala (10) sich unterhalb eines Fensters (18) in einem Gehäuse
(14) befindet, und dass das Antriebsrad (7) auf einer Antriebswelle (8) befestigt
ist, das aus einer Seitenwand (16) des Gehäuses (14) vorsteht.
13. Mechanismus nach einem der Ansprüche 9 bis 12, dadurch gekennzeichnet, dass kuppelförmige
Transportzähne (21) am Antriebsrad (7) vorgesehen sind, die mit einem Beeinflussungssitz
in Löchern des Bandes (5) eingreifen.
14. Mechanismus nach einem der vorhergehenden Ansprüche 1 bis 13, dadurch gekennzeichnet,
dass die Beeinflussungsmittel (15) im wesentlichen keilförmig ausgebildet sind (Fig.
2 und 4).
15. Mechanismus nach einem der Ansprüche 1 bis 13, dadurch gekennzeichnet, dass die
Beeinflussungsmittel (15) zwei im wesentlichen parallel beabstandete keilförmige Abschnitte
(15) (Fig. 4b) umfassen.
16. Mechanismus nach einem der Ansprüche 1 bis 13, dadurch gekennzeichnet, dass die
Beeinflussungsmittel (15) aus einer Vielzahl von beabstandeten Segmenten unterschiedlicher
Breite, Grösse, Beabstandung, Dichte oder dergleichen bestehen (Fig. 4c, 4d, 4e).
17. Miniaturarmbanduhrradio mit einem variablen Induktormechanismus (Fig. 5) zum Abstimmen
des Radios, welcher Mechanismus einem solchen entspricht, wie er in einem der vorhergehenden
Ansprüche beansprucht ist und dass sich der Mechanismus in einem Gehäuse (14) befindet
(Fig. 6).
1. Mécanisme à inductance variable comprenant une bobine (1) et un moyen d'influence
(15) pour influencer l'inductance de la bobine (1) selon la position transverse du
moyen d'influence par rapport à l'axe de la bobine, caractérisé en ce que le moyen
d'influence (15) est soutenu par une bande flexible (5) mobile longitudinalement dans
une direction généralement transverse à l'axe de la bobine (1) ou fait partie de cette
bande.
2. Mécanisme selon la revendication 1, caractérisé en ce que le moyen d'influence
(15) est mobile selon un trajet qui coupe l'axe de la bobine (1) de façon générale
à angle droit.
3. Mécanisme selon l'une des revendications 1 ou 2, caractérisé en ce que le moyen
d'influence (15) est stratifié sur une surface de la bande (5).
4. Mécanisme selon la revendication 3, caractérisé en ce que le moyen d'influence
(15) est appliqué à des parties choisies de la surface de la bande (5) de sorte que
son influence sur la bobine (1) varie en fonction de la partie de la bande (5) qui
est alignée avec l'axe longitudinal de la bobine.
5. Mécanisme selon l'une des revendications 1 ou 2, caractérisé en ce que le moyen
d'influence (15) constitue son propre support.
6. Mécanisme selon l'une quelconque des revendications précédentes, caractérisé en
ce que le moyen d'influence (15) est complètement constitué d'un matériau conducteur
ou de tout autre matériau capable de faire varier l'inductance de la bobine.
7. Mécanisme selon l'une quelconque des revendications précédentes, caractérisé en
ce que la bande (5) a la forme d'une boucle sans fin.
8. Mécanisme selon la revendication 7, caractérisé en ce que la boucle sans fin (5)
est entraînée par un tambour denté d'entraînement (7) et passe autour d'un rouleau
de tension (9).
9. Mécanisme selon l'une des revendications 7 ou 8 prises dans leur dépendance d'avec
les revendications 3 ou 4, caractérisé en ce que la boucle de bande (5) est constituée
d'un matériau mince de polyester ou de polyimide, une couche conductrice (15) constituée
de cuivre ou d'un autre métal ou de toute autre substance capable de faire varier
l'inductance de la bobine (1) étant gravée ou déposée d'une autre manière sur une
surface de la bande (5).
10. Mécanisme selon la revendication 9, caractérisé en ce que la couche conductrice
(15) a une forme de coin, l'axe longitudinal du coin s'étendant selon l'axe de la
bande (5), de sorte que, quand la bande est amenée à avancer devant l'axe longitudinal
de la bobine (1), la largeur de la couche conductrice augmente ou décroît, faisant
ainsi varier l'inductance de la bobine (1).
11. Mécanisme selon l'une quelconque des revendications 7, 8, 9 ou 10, caractérisé
en ce qu'une échelle de fréquences (10) est imprimée sur la bande (5) et en ce que
l'agencement est tel que quand la partie inférieure de la boucle (15) se déplace en
regard de l'axe de la bobine, l'échelle (10) est visible et se déplace le long de
la partie supérieure de la boucle (15).
12. Mécanisme selon la revendication 11, caractérisé en ce qu'il est incorporé dans
un récepteur radio miniaturisé qui peut être porté au poignet d'une personne, et dans
lequel l'échelle (10) est située en regard d'une fenêtre (18) dans un boîtier (14),
et la roue dentée d'entraînement (7) est montée sur un arbre d'entraînement (8) faisant
saillie à partir d'une paroi latérale (16) du boîtier (14).
13. Mécanisme selon l'une quelconque des revendications 9 à 12, caractérisé en ce
que des dents en forme de dôme (21) du tambour denté sont prévues sur le tambour d'entraînement
(7) pour s'engager étroitement avec des trous prévus dans la bande (5).
14. Mécanisme selon l'une quelconque des revendications 1 à 13 précédentes, caractérisé
en ce que le moyen d'influence (15) a une forme générale de coin (figures 2 et 4).
15. Mécanisme selon l'une quelconque des revendications 1 à 13, caractérisé en ce
que le moyen d'influence (15) comprend deux parties (15) en forme de coin généralement
parallèles et espacées (figure 4b).
16. Mécanisme selon l'une quelconque des revendications 1 à 13, caractérisé en ce
que le moyen d'influence (15) est constituée d'une pluralité de segments espacés de
différentes largeurs, dimensions, espacements, densités ou analogue (figures 4c, 4d
et 4e).
17. Montre radio de poignet miniaturisée comprenant un mécanisme à inductance variable
(figure 5) pour accorder la radio, ce mécanisme étant tel que revendiqué dans l'une
quelconque des revendications précédentes et étant situé dans un boîtier (14) (figure
6).