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Патент USA US2134913

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Nov. 1, 1938.
A, w, EDWARDS
.
2,134,913
RADIO OR LIKE RECEIVER
Filed Dec. 4, 1936
(5%.
5 Sheets-Sheet l
Nov. 1, 1938.
A. w. EDWARDS
RADIO OR LIKE RECEIVER
Filed Dec. 4, 1936‘
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2,134,913
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5 Sheets-Sheet 2
Nov. 1, 1938.
A. w. EDWARDS
2,134,913
RADIO OR LIKE RECEIVER
Filed Dec° 4', 1956
5 Sheets-Sheet 3
2,134,913
Patented Nov. 1, 1938
UNITED STATES PATENT OFFICE
2,134,913
RADIO 0R LIKE RECEIVER
Arthur Wallace Edwards, Hollinwood, England,
assignor to Ferranti Electric Inc., New York,
N. Y.
Application December 4, 1936, Serial No. 114,272
In Great Britain December 7, 1935
6 Claims.
This invention relates to radio or like receivers
of the type incorporating one or more band-pass
?lter stages such as, for instance, an intermediate
frequency stage of a superheterodyne receiver.
In receivers of this type, the wider the fre»
quency band passed through the receiver, the
better is the ?delity of the reproduction to the
transmission being received. In order to permit
the passage of a wide frequency band the re~
sponse curve of each band-pass ?lter stage should
be of the double hump form; the width of fre
quency band that can be passed for any given
transmission being received differs according to
the strength of the transmission, and conse
quently the shape of the response curve also
differs. It is well known that tuning of receivers
under conditions of a wide response curve is dif?
cult owing to there being a number of positions
of the tuning apparatus for which apparently
20 similar results are obtained.
It is desirable therefore to narrow the fre
quency band passed through the receiver to cor
respond with a response curve having a single
peak before performing the tuning operation,
(01. 250-20)
Figure 6 is an enlarged side View of part of
the coil operating mechanism.
Figure 7 is an enlarged end view of said part
of the coil operating mechanism, and
Figure 8 is an enlarged plan view of said part of
the coil operating mechanism.
In carrying the invention into effect according
to the form illustrated by way of example as ap
plied to a superheterodyne radio receiver, I con
struct the intermediate frequency transformer in
li)
such a manner as to have its two coils a, b mount-
ed coaxially, the coil or being ?xed rigidly to a
tubular member 0 and the coil 12 being mounted
upon a sleeve 07. capable of movement in an axial
direction along the tube 0.
A tube 1‘ is slidable within the tube 0 and car
ries a radial pin g by which the tubes d and f are
constrained to move together as one in a vertical
direction; vertical slots 72. in the tube 0 through
which the pin g passes are provided to present Lit)
this vertical movement. A cranked rod e is piv
oted to the tube J‘ and to a slotted plate 7' and is
carried in ?xed forks 76 whereby rotation of a
shaft 75 carrying an arm q with a pin m engag
ing the slot 11 in the plate 9' effects a rise or fall
25 after which process the band Width passed is in
creased to suit the transmission being received. 1 of the coil b. The shaft t is coupled to a shaft
To effect this procedure it has been proposed 0 passing through the front of the cabinet (not
to provide manual means for ensuring that before shown) containing the receiver, a knob p being
attached to the shaft 0.
the receiver can be tuned to the required trans—
Associated with the shaft 0 is a ?delity con
30 mission and the coupling between the coils then
increased in order to widen the frequency band trol device which comprises a notched wheel r
passed through the receiver, the coupling between
the two members of each band-pass ?lter stage
mounted frictionally on the shaft, being held by
must be decreased, with the result that the re
sponse curve of the ?lter is caused to be of the
The degree of friction is such that when the
notched wheel 1" is held, a spring u tending to
rotate the shaft t in a counterclockwise direction
in Figures 3 and 4 is unable to rotate the shaft.
Two pins or ?ngers v, 12’ attached rigidly to or
single peak form.
The object of this invention is to provide im
proved or simpli?ed means for achieving such
result.
40
The invention consists in a radio or like re
ceiver incorporating features set out in the claims
appended hereto.
Referring to the accompanying diagrammatic
drawings:—
Figure 1 is a perspective view of part of a
tuning apparatus embodying the present inven
tion in one form.
Figure 2 is an enlarged side view of the inter
mediate frequency transformer coils and mount
50 ing thereof with part of the enclosing case broken
away.
Figures 3 and 4 are enlarged end views of part
of the tuning and ?delity control mechanism.
Figure 5 is an enlarged side view of said part
of the mechanism.
means of a spring washer or the like (not shown).
forming part of the lower ends of two approxi
mately diametrically opposite arms w, a: co-oper~
ate with the notched wheel r in such a manner
that when one pin or ?nger v, o’ is in engage
ment with the wheel 1", the other bears against
the periphery of the wheel between two ad
jacent notches. The two arms to, a: are pivoted to
each other at the mid-point of each. A cam s is
45
provided in driving relationship with the shaft
and adjacent to the notched wheel 1'; this cam has
two approximately diametrically opposite lifts 50
y, z, the lift 2 being provided with a stop 2 at the
top thereof. The ?ngers follow the cam when
ever the latter rotates, riding up the lifts until
the stop prevents further rotation of the cam. A
subsidiary spring 3 is disposed on the pivot 4
2
2,134,913
between the two arms so as to urge both ?ngers
v, 22' towards the notched wheel r.
The tuning apparatus includes a spindle 5
which latter is mounted parallel to the shaft 0.
Til A star wheel 6 is ?xed rigidly on this spindle.
Two studs 1, 8, one attached to each of the re
mote ends of the two arms referred to above, co
operate with the star wheel ‘6 in such a manner
that in the position shown in Figure 3 the arm
£23 engaged by the ?nger v’ with the notched wheel
r is also engaged by a stud with the star wheel 6,
the other arm 20 being held out of engagement
with the notched wheel 1' by the pin 8 engaging
the star wheel 6.
In operation, assuming the receiver to have
been tuned to a particular station and the cou—
pling between the coils a, b of the intermediate
frequency transformer to have been adjusted to
give a response curve suited to the station in ques
tion; upon rotating the tuning spindle 5, with the
object of effecting a change in the station being
received, the star wheel 5 rotates therewith and on
the ?rst movement the pin 1 which is in engage—
ment with it is forced outwards so that the ?nger
v’ on the opposite end of the arm at to which the
pin 7 is attached is lifted out of engagement with
the notched wheel r. Thus the notched wheel is
no longer held and the spring it causes the shafts
t, o to rotate into the position shown in Figure l
30 and the movable coil b of the intermediate fre
quency transformer to move towards its lower
most position.
The cam s on the shaft 0 rotates with the shaft
sufficiently for the two swell portions 1/, z to lift
and retain the two ?ngers o, 2;’ out of contact
with the notched wheel r, thus simultaneously
preventing the pins 7, 8 on the opposite ends of
the arms from contacting or re-engaging with
40
the star wheel 6.
The mechanism now occupies the position
shown in Figure 4. The tuning spindle 5 is now
free to be rotated without actuating the arms 10,
m and it may be adjusted into any desired posi
tion.
When the receiver has been retuned to the de
sired station, the operator turns the knob 11 at
tached to the shaft 0 in order to move the mova
ble coil 73 nearer to the ?xed coil it until the cou
pling is such as to give a response curve suited
to the new station.
This operation rotates the
cam s in clockwise direction and allows the ?n
gers to drop from the swells or lifts of the cam to
contact with the notched wheel 1', e. g. as shown
in Figure 3.
I
As soon as one or other of the two ?ngers en
gages with the notched wheel the latter is ar
rested and the pins 1, 8 are brought into opera
tive engagement with the star wheel 6 ready for
the next retuning process, but the knob p may be
60 moved to vary as desired the position of the mov
ing coil 21 since the notched wheel r remains
locked.
The teeth of the notched wheel 1" are so shaped
as to ensure that one or other ?nger v, 12’ will
drop into a notch.
The stop 2 on the cam 8 may be employed as
an audible indicating device, the sound caused
When it strikes the ?nger 2i’ acting as an indica
tion to. the operator that the receiver is in its
high selectivity condition.
The arrangement described for enabling rota
tion of the shafts to effect movement of the coil
on the intermediate frequency transformer is by
way of example only and does not form part of
75 the invention.
Having now described my invention what I
claim as new and desire to secure by Letters Pat
ent is :—
1. A receiver incorporating an adjustable band
pass ?lter circuit, a tuning control device, means
actuated by mere rotation for tuning purposes of
said tuning control device automatically reduc
ing to a pre-set minimum the frequency range of
responsiveness of said band-pass ?lter circuit
and a further control device for subsequently in
10
creasing to any desired extent the frequency
range of response.
2. A receiver as claimed in claim 1 wherein
the said band-pass ?lter circuit includes rela
tively movable members for varying the degree 15
of coupling and in addition there is provided
as part of said means actuated by mere rotation
of said tuning control device a return spring for
urging the said members to adopt a position cor
responding to minimum frequency range of re
sponsiveness of said band-pass ?lter circuit, re
taining means for preventing the said members
from responding to the action of the said return
spring and further means associated with said
tuning control device operable to release said re
taining means upon variation of the position of
said tuning control device.
3. A receiver as claimed in claim 1 wherein
the said band-pass ?lter circuit includes rela
tively movable members for varying the degree
of coupling, there is provided as part of said
means actuated by mere rotation of said tuning
control device a return spring for urging said
members to adopt a position corresponding to
minimum frequency range of responsiveness of
said band-pass ?lter circuit, retaining means for
20
25
30
35
preventing the said members from responding to
the action of said return spring, and further
means associated with said tuning control de
vice operable to release said retaining means up 40
on variation of the position of said tuning control
device and wherein said retaining means include
a notched wheel mounted frictionally on a shaft
operatively associated with said relatively mov
able members and two arms are provided having
a ?nger on one end of each arm, the ?ngers being
urged into engagement with said notched wheel
by the action of a subsidiary spring, the arrange
ment being such that when one of the pins en
gages a notch the other contacts with a tooth.
4. A receiver as claimed in claim 1 having rel 50
atively movable members for varying the degree
of coupling in said band-pass ?lter circuit and
wherein said means actuated by mere rotation
of said tuning control device include a return
spring for said members, retaining means for 55
said members, releasing means for said retaining
means operable by said tuning control device,
said retaining means including a notched wheel
mounted frictionally on a shaft operatively asso
ciated with said relatively movable members, two
60
arms having a ?nger on one end of each, the ?n
gers being urged into engagement with said
notched wheel by a subsidiary spring, said releas
ing means associated with said tuning control de 65
vice serving to release a ?nger from engagement
with said notched wheel, and a cam serving to
prevent engagement or re-engagement between
the ?ngers and the notched wheel upon rotation
of said shaft having been effected by said return 70
spring.
5. A receiver as claimed in claim 1 including
as part of said means actuated by mere rotation
of said tuning control device a cam, a pair of
arms having ?ngers at both ends of each, a 75
2,134,913
3
notched wheel associated with one pair of ?n
?delity control shaft associated with said rela
gers, a star wheel associated with the other pair
of ?ngers, a cam associated with said notched
wheel, a part on said cam co-operating with a
tively movable members, a. notched wheel on said
shaft, a star wheel associated with said tuning
control device, a pair of arms having ?ngers on
stop and a return spring for urging said part of
the cam into engagement with the stop.
6. A receiver including in combination an ad
both ends of each, the ?ngers on the opposite
ends of one arm simultaneously respectively ly
ing between a pair of teeth on the star wheel and
engaging a notch in the notched wheel whilst the
?ngers on the opposite ends of the other arm
simultaneously respectively rest upon the ex 10
justable band-pass ?lter circuit having two rela
tively movable members for varying the degree
10 of coupling, a return spring for urging said
members into a position corresponding to mini
mum frequency range of responsiveness of said
band-pass ?lter circuit, a tuning control device, a
tremity of a star wheel tooth and a notched wheel
tooth.
ARTHUR WALLACE EDWARDS.
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