Ear mounted RF receiver

A radio frequency receiving device which is totally self contained and is fully supported at a diverging opening of a user's ear extending from the ear canal. The device includes an elongate casement having a lower portion and an upper portion at a total length of less than two inches. The casement is constructed of a top portion and a bottom portion, the top portion being deflected from the bottom portion by an acute angle whose value is between the range of 10 to 30 degrees. The bottom portion includes a speaker device mounted at a proximal side thereof and being configured to frictionally fit at the diverging ear opening in close proximity to the skull, with the upper half resting against the ear or being in frictional contact with an upper lip of the ear extending from the top cartilage. The device includes a printed circuit board contained within the casement, a battery compartment, on/off power and volume switches and a tuning circuit for providing selection of desired frequency. The total structure is housed within the casement and weighs less than 2.5 ounces.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to radio frequency (rf) receivers which can be 
positioned in the ear of a user. More particularly, it pertains to an ear 
mounted radio which is totally self-contained and requires no additional 
structural support to maintain its fixed, ear mounted position. 
2. Prior Art 
Since early conception of small sized radios, various innovations have been 
made to place such radios at the ear of the user. Most of these devices 
rely on a hook or loop which extends around the outside of the ear, 
suspending the attached speaker and radio circuitry at the opening of the 
ear canal. Without the hook, the radio falls from the ear with a slight 
jar. The challenge of placing the radio at the ear in a self-supported 
mode is further increased by the need to compete with the high quality 
sound generated in state of the art receivers. Such quality requires more 
filters, complex balancing circuits, enhanced amplifiers and similar 
refinements which add to the volume of space required and attendant 
weight. 
Less expensive receivers have been developed with a lower quality and have 
maintained some stability when mounted at the ear canal. The present 
inventor has also produced an AM radio receiver which relied on a unique 
design for an oscillator as described in U.S. Pat. No. 4,539,708. This AM 
receiver has likewise enjoyed only minimal commercial success. This was 
due in part to limited sound quality and a mechanical tuning circuit that 
was somewhat awkward. More importantly, the structural shape of the radio 
was not optimal for maintaining stable contact at the ear opening. 
Generally, the design parameters applied to this receiver were limited to 
AM radios, and were not well suited for extensions into other types of 
receivers such as FM radio devices. 
Another factor which has greatly limited the marketability of an ear 
mounted radio is cost. Typical consumers will only purchase such devices 
if the cost is minimal. Furthermore, a high cost ear receiver cannot 
compete with larger, more powerful systems which sell at the same price, 
even though they may not be mountable at the ear. For this reason, prior 
art attempts to place the receiver at the ear have been more of a novelty 
item than representative of a quality radio. 
Such low cost and poor quality have created a market expectation that 
future ear mounted radios are likely to be of lower quality and should 
likewise be in a lower price range. In order to overcome this expectation, 
it is necessary to overcome the cost problem while enhancing the quality 
of sound. These seeming contradictory objectives of cost versus quality 
must be resolved within a very narrow range of physical limitations which 
meet the minimal size and weight requirements necessary to retain radio 
self supported when positioned at the ear. 
OBJECTS AND SUMMARY OF THE INVENTION 
It is an object of the present invention to provide an RF receiver which is 
sufficiently small to be positioned and retained in the ear opening of a 
user during normal use. 
It is a further object of this invention to provide such a receiver which 
has a compact design and configuration which places the center of mass of 
the ear radio close to the ear canal opening to reduce the likelihood of 
being dislodged during use. 
It is yet another object of the invention to provide a receiver that 
provides high quality sound reproduction, yet includes a casement 
configuration which is small enough to be mounted at the ear opening. 
Yet another object of this invention is to provide a receiver which can be 
manufactured in small size and inexpensively, but which yields high 
quality sound reproduction. 
These and other objects are realized in a radio frequency receiving device 
which is totally self contained and is fully supported within a diverging 
opening of a user's ear extending from the ear canal. The device includes 
an elongate casing having a lower half and an upper half and a total 
length of less than two inches. The front and back comprise a proximal 
face and an opposing distal face relative to the user's ear, each face 
having a width of less than three fourths of an inch. A surrounding 
perimeter wall including a bottom wall, a top wall and two opposing side 
walls completes the enclosure, each wall representing a thickness 
dimension for the device of less than one fourth of an inch. The proximal 
face includes a speaker device mounted to the casement which projects 
toward the user's ear canal. The speaker device is configured to 
frictionally position and stabilize the receiver device within the 
diverging ear opening. Functional operation of the device is provided by a 
printed circuit board contained within the casement, said board having 
interconnecting functional receiver circuits including a local oscillator, 
a mixer, a plurality of IF stages, a phase lock loop demodulator and a 
power source. Antenna means coupled to the oscillator provides RF 
reception. The device includes a battery compartment within the casement 
and associated wiring to couple the battery compartment to the circuit 
board. An on-off power and volume control switch is coupled within the 
casement to the printed circuit board and a tuning circuit selector switch 
is coupled to the printed circuit board for selecting a specific frequency 
for reception. All of these components are housed within the casement and 
have a collective weight of less than 2.5 ounces, thereby enabling the 
device to be suspended within the diverging ear opening without additional 
support applied with respect to outer surfaces of the ear or the user's 
head. A third point of frictional contact may also be applied between a 
top edge of the casement at the crown of the ear cartilage.

DETAILED DESCRIPTION OF THE INVENTION 
Referring now to the drawings, the following description provides specific 
disclosure of a preferred embodiment of the present invention: 
An FM receiver 10 is shown generally in its mounted position with respect 
to an individual's ear 11. This receiver is representative of any 
receiving device useful for reception of radio frequency signal within the 
audio range. Obviously, this would include AM and short wave transmissions 
as well as the illustrated FM band width. 
This receiver 10 is totally self contained and is fully supported within a 
diverging opening 12 of the user's ear extending from the ear canal. This 
diverging opening refers particularly to that portion of ear cartilage 
which extends from the ear canal outward to form a wave guide cavity 
having a general concave structure 13 at the back part of the ear, and a 
forward lobe 14. These opposing sections of ear cartilage together provide 
forward and rearward tissue having sufficient stiffness to frictionally 
retain an object of appropriate size placed therebetween. 
The combination of this frictional support and a unique configuration for 
the receiver 10 enables the radio to maintain its seated position, despite 
significant movement on the part of the user. The receiver configuration 
is formed primarily by an elongate casing having a lower half 16 and an 
upper half 17, which is slightly angled outward as illustrated in FIG. 1. 
This angled configuration enables the lower portion 16 of the casing to 
rest in closest possible proximity to the ear, in a seated position within 
the diverging opening 12. This occurs because the angled upper half 17 
extends away from the top cartilage 18, allowing the lower half 16 to 
fully nest against the ear canal. Except for this deflection of the upper 
half 17 from the plane 19 of the lower half, the upper ear cartilage 18 
would block the casing from being positioned in this close position. As a 
consequence, the center of mass of the radio would be displaced from this 
preferred mounting location and the maximum frictional contact with the 
diverging opening of the ear would be frustrated. 
The present inventor has discovered that the casement as configured in the 
figures provides enough space to contain the battery power supply, 
switching mechanisms for volume, power and tuning, as well as the 
associated circuitry required for high fidelity reproduction. For example, 
a representative circuit diagram is illustrated in FIG. 3. It is formed as 
part a printed circuit board 20 with an associated integrated chip 21 
contained within a surrounding casement 22 and 23 which forms the casing 
for the radio 10. This board includes interconnecting, functional receiver 
circuits such as a local oscillator, a mixer, a plurality of IF stages, a 
phase lock loop demodulator and a power coupling. 
This circuit board 20 is contained within the casement 22 and 23 in a 
folded configuration wherein part of the printed circuit is contained on a 
first folded section 25 of the board and functions as an on/off volume 
device. Separate wires connect from the board to speaker device 27 which 
is supported on casement 22. The remaining, second folded section 26 of 
the board provides contacts for activating and resetting the tuning 
circuit for selection of a desired FM signal. 
Although other frequency selections systems may be applicable, the 
touch-tune system provides simplicity and convenience, as well as 
compactness in size. This touch operated switch is activated through an 
on/off circuit sandwiched between touch points 30 and 31 located at an 
exterior surface of the casement 23 and circuit contacts concealed on an 
opposing side of the second folded section 26 of the printed circuit 
board. Touch points 30 and 31 and tuning circuit contacts are aligned such 
that physical pressure applied to the touch points closes the tuning 
circuit selector switch, causing the selector to scan for the next 
frequency having adequate signal strength for reception. Such touch 
operates switches are well known generally, but have not been applied in 
this manner with an ear radio which is totally self contained and self 
supported. 
By using this configuration and circuitry, it has been discovered, quite 
surprisingly, that receiver sensitivity as low as 4 microvolts are 
possible with excellent reproduction of sound. Typical good quality FM 
receivers require approximately 50 microvolt RF signal strength to lock on 
a channel during scanning operation. This sensitivity has been 
experimentally verified on a full circuit scanning range from 88 to 108 
Khz which was applied to the present embodiment. 
Reception is initiated by a conventional antenna means coupled to the 
oscillator for providing RF reception. For near area signals, the antenna 
may be housed within the casement 22. The present invention illustrates 
the use of a removable antenna 35 which can be attached to a port 36 on 
the casing exterior to extend or improve reception at greater distances. 
A battery compartment 40 is housed within the casement and can be removed 
by sliding the compartment free from the upper half of the casing through 
opening 41. This compartment is shown with two battery insert slots 42 for 
providing a total of 3 volts dc power source to the circuitry. A top wall 
or cap 45 structurally closes the casement and provides mounting support 
to the antenna and battery compartment. Associated wiring (not shown) 
couples the battery compartment to the circuit board. This battery power 
source is wired in series through an on/off power and volume control 
switch 50 which is mounted to the casement exterior to provide touch 
access by the user. 
A speaker device 27 is mounted to the casement at the lower half 16, 
approximately opposite to the touch points 30 and 31. This arrangement 
enables the user to apply a full contact force against the touch points 
without pushing the receiver into a less stable location. In fact, any 
perpendicular force applied to the touch points will tend to reinsert the 
speaker device 27 within the diverging opening 12, if some slippage has 
occurred. It is for this reason, in part, that the tuning switches, 
circuit board and speaker device have been aligned with the diverging ear 
opening 12, to ensure that the receiver remains balanced at the self 
supported position, even during manipulations of tuning and positional 
adjustment. 
The speaker device comprises a generally circular speaker enclosure as is 
illustrated. Obviously, other configurations are plausible, provided the 
enclosure is configured to provide a snug fit within the diverging opening 
of the ear. 
Although most of the components making up the functional circuitry are 
individually known to those skilled in the art, their association as part 
of a self-contained ear radio was not self evident. The general 
predisposition of the industry suggested against effective reduction of 
such circuitry to a small size in an economical manner because of inherent 
size and weight limitations. Accordingly, an important aspect of novelty 
of this invention is the combination of these components within a 
structural arrangement and configuration that makes the self-supported ear 
radio feasible, despite the contrary disposition within the art. The 
structural arrangement of the components has been set forth above. The 
configurational will now be considered. 
As was mentioned, the casing is an important part of the feasibility of the 
receiver. It not only encloses the components in workable relationship, 
but provides the compactness and configuration to enable firm retention at 
the ear. This arises in part because of the flattened, elongate shape of 
the casement which permits its placement immediately at the ear canal of 
the user. The actual length of the casement may extend from one to two 
inches; however, optimal length is provided when the upper edge 70 of the 
casement contacts the inner lip 71 of the ear cartilage when the receiver 
is correctly seated at the diverging opening 12. This establishes 
triangular contact points at 13, 14 and 71, which greatly stabilizes the 
receiver because of frictional contact between the user's skin and the 
casement. 
It is apparent that the relationship of the upper edge 70 with the ear lip 
71 will be a function of the position of the speaker device 27. In the 
preferred embodiment, this speaker device is positioned at a lower, 
central portion of a proximal face 74 of the lower half of casing 22. In 
this configuration, most of the weight of the receiver is above the ear 
contacting surface at the lower edge 75 and periphery 76 of the speaker 
device. The opposing distal face 77 (concealed in FIG. 2) includes the 
touch points 30 and 31 as discussed above. 
These proximal and distal faces, relative to the user's ear, have a width 
of less than three fourths of an inch, and are attached to a surrounding 
perimeter wall 80 and 81, comprising a bottom wall, a top wall and two 
opposing side walls, each wall having a combined thickness of less than 
one fourth of an inch. Actual dimensions of the device illustrated in the 
figures are a uniform combined wall thickness of 3/16ths of an inch, with 
each face being 1/2 inch in width. The total length of the receiver is 1 
and 1/2 inches, with the upper half being approximately 7/8ths of an inch 
in length, and the lower half being approximately 5/8ths of an inch. It 
will be apparent that the designations of upper and lower halves are 
intended to be general approximation, and not a mathematical statement of 
relative comparison. 
It is important to note that the casing and all components within the 
casement have a collective weight of less than 2.5 ounces, and preferably 
1.5 oz., thereby enabling the device to be suspended within the diverging 
ear opening without additional support applied with respect to outer 
surfaces of the ear or the user's head. 
The extent of divergence of the upper half of the casement from the plane 
of the lower half of the casement is represented by angle 90. It will be 
apparent that variations in anatomy will favor differing angles, depending 
upon the extent to which the top ear cartilage is displaced from the 
user's skull. Generally this displacement will be within the range of 
10-30 degrees, with a preferred value of approximately 20 degrees 
deflection.