U.S. patent number 3,748,583 [Application Number 05/216,674] was granted by the patent office on 1973-07-24 for portable radio with integral acoustical horn.
This patent grant is currently assigned to Motorola, Inc.. Invention is credited to Todd G. Andersen, Donald Y. Ing.
United States Patent |
3,748,583 |
Andersen , et al. |
July 24, 1973 |
PORTABLE RADIO WITH INTEGRAL ACOUSTICAL HORN
Abstract
A portable radio receiver having a rectangular elongated housing
with a first rectangular elongated compartment, and a second
rectangular elongated compartment adjacent the first compartment.
An interior partition wall separates the two compartments. The
second compartment has a passage therein which forms an acoustical
horn. A removable radio receiver chassis including a transducer
device is seated in the first compartment. An acoustical chamber
secured in the first compartment couples the transducer to the
acoustical horn which amplifies and emits the sound waves.
Inventors: |
Andersen; Todd G. (Lombard,
IL), Ing; Donald Y. (Chicago, IL) |
Assignee: |
Motorola, Inc. (Franklin Park,
IL)
|
Family
ID: |
22808038 |
Appl.
No.: |
05/216,674 |
Filed: |
January 10, 1972 |
Current U.S.
Class: |
455/348; 181/177;
455/351 |
Current CPC
Class: |
H04B
1/086 (20130101) |
Current International
Class: |
H04B
1/08 (20060101); H04b 001/08 () |
Field of
Search: |
;325/352,353,355,356,361,16 ;179/1E ;181/27A,27C,27D |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Griffin; Robert L.
Assistant Examiner: Moore; William S.
Claims
We claim:
1. In a portable radio receiver adapted to be carried by a user,
the combination including; a rectangular elongated housing having a
first rectangular elongated compartment formed therein, a second
rectangular elongated compartment formed therein adjacent said
first compartment, and an interior partition wall formed between
and separating said first and second compartments, said second
compartment having a passage therein forming an acoustical horn, an
acoustical chamber formed in said first compartment having a first
aperture for allowing entry of sound waves, an expanding spiral
conduit formed therein for allowing transmission of said sound
waves, and the second aperture for allowing exit of said sound
waves, said interior partition wall having an aperture therethrough
for coupling said sound waves from said acoustical chamber second
aperture to said second compartment acoustical horn, compressible
coupling means mounted to the walls of said second aperture in said
acoustical chamber, removable radio receiving means forming a
complete self-contained operable radio and including transducer
means for converting electrical waves to said sound waves and
having an output opening for said sound waves, said radio receiving
means being seated in said first compartment, said coupling means
being compressed by said transducer means between said transducer
means output opening and said acoustical chamber for coupling said
sound waves to said acoustical chamber, said radio receiving means
and transducer means being completely physically separable from
said coupling means for allowing removal and independent operation
of said radio receiving means.
2. The portable radio receiver of claim 1 wherein said housing
further includes top, bottom and side walls, said interior
partition wall extending from said top wall to said bottom wall,
said transducer means being positioned adjacent said top wall and
said interior partition wall, said passage in said second
compartment having a first portion extending in a direction away
from said top wall towards said bottom wall for coupling said sound
waves in said direction, a second portion extending in a direction
away from said bottom wall to said top wall for coupling said sound
waves in said direction, a third curved portion coupling said first
and second portions for coupling said sound waves from said first
portion to said second portion, and an aperture in said top wall
for allowing emission of said sound waves from said second portion,
said first, second and third portions being so designed that their
cross sectional area expands approximately hyperbolically and
terminates at said aperture in said top wall.
3. The portable radio receiver of claim 2 wherein said acoustical
horn has a primary resonant frequency response at approximately
2,000 cycles, and an acoustical reflection resonant frequency
response at approximately 700 cycles.
4. The portable radio receiver of claim 3 wherein said transducer
means includes an electroacoustic transducer for converting
electrical waves to sound waves, and a housing for mounting said
transducer therein, said housing having a spiral passage therein
coupling said transducer to said transducer means output opening
and being operative to drive said acoustical chamber.
5. The portable radio receiver of claim 4 wherein said coupling
means includes, a resilient cylindrical member having an outer
wall, an aperture axially extending therethrough, and a
circumferential groove cut in the outer wall adjacent one end of
said cylinder, said walls of said first aperture in said acoustical
chamber being inserted in said groove for securing said coupling
means thereto, and said transducer means output opening being
adjacent the other end of said cylinder, said transducer sound
waves being coupled from said transducer means output opening
through said coupling means aperture to said acoustical
chamber.
6. The portable radio receiver of claim 5 wherein said coupling
means is made of rubber.
Description
BACKGROUND
In a small, portable radio apparatus such as a receiver or pager,
to be carried by a user, speakers have been used to convert the
received, demodulated signals to audio signals. Although such
speakers have been used effectively for a number of years, they
suffer from a number of disadvantages. A speaker does not have a
flexible physical form factor. It is normally restricted to a
circular or oval configuration, for speakers which are designed to
reproduce speech. Because of this inflexible form factor, radio
receivers must be designed around the speaker, resulting in a bulky
package for the apparatus. The speaker in such an apparatus may
account for as much as one-third of the total volume.
Speakers are also low efficiency devices. A relatively large
battery and substantial circuitry must be used in order to produce
a signal having the amplitude to produce a usable sound level from
a speaker. This further increases the size of the radio apparatus.
Furthermore, the speaker's location in an apparatus worn by a user,
causes the sound to be directed away, rather than towards the
user's ear making it difficult to hear a received message, and
resulting in a less efficient use of the available power.
Transducers and acoustical horns have been used with portable radio
apparatus such as pagers or receivers. The acoustical horn in such
units is an exponential horn, and is made large in order to develop
the necessary sound levels. The horn and transducer constitute a
single assembly with the transducer coupled directly to the horn.
Because of the integral transducer, and the size and configuration
of the exponential horn, the assembly is quite large. The assembly
because of its size must be added as a separate unit to the
sidewall of the radio apparatus. This makes the entire radio
apparatus package large and bulky, and difficult to carry in a
user's pocket or on his belt. The size of the horn and its
resulting form factor also prevent the sound from being directed
towards the user's ear when worn in the pocket or on the belt.
With the transducer and horn mounted external to the radio
apparatus the entire radio chassis, including the transducer,
cannot be easily removed and tested as a complete radio package. It
is desirable for the entire radio chassis, including the
transducer, to be easily removable and independently operable so as
to facilitate testing and assembly of the unit, and to allow the
radio to be used in a number of housings having various
configurations. If the transducer is to be included as a part of
the radio chassis rather than as a part of the housing or horn
assembly, means must be provided for releasably coupling the
transducer to the acoustical horn without reducing the efficiency
of the horn or affecting the characteristics of the reproduced
audio signals.
SUMMARY
It is an object of this invention to provide an improved portable
radio apparatus including a housing having an integral acoustical
horn.
Another object of this invention is to provide an improved portable
radio apparatus including a transducer device, which is easily
detachable from the housing and acoustical horn.
Yet another object of this invention is to provide an improved
portable radio apparatus having a self-contained radio receiver
chassis which is operable when removed from the housing.
Still another object of this invention is to provide a portable
radio apparatus having a miniaturized high efficiency acoustical
horn.
A still further object of this invention is to provide a portable
radio apparatus having a housing including means for coupling a
removable transducer to an integral acoustical horn.
In practicing this invention, a portable radio receiver is provided
having an elongated rectangular housing with a first rectangular
elongated compartment and a second rectangular elongated
compartment adjacent the first compartment. An interior partition
wall having an aperture therethrough separates the two
compartments. The second compartment has a passage therein which
forms a hyperbolic acoustical horn, with the mouth of the horn at
the top of the unit so as to direct sound towards the user. A
removable radio receiver chassis, including a transducer device, is
seated in the first compartment. An acoustical chamber secured in
the first compartment has a first aperture for allowing entry of
the sound waves from the transducer, and a second aperture coupled
to the aperture in the interior partition wall for allowing exit of
the sound waves into the acoustical horn. A coupling device mounted
to the walls of the first aperture in the acoustical chamber,
releasably couples the transducer to the chamber. The hyperbolic
acoustical horn has a primary resonant frequency at approximately
2,000 cycles, and an acoustical reflection resonant frequency at
approximately 700 cycles. These two resonances enhance the audio
reproduction capabilities of the hyperbolic acoustical horn thus
increasing its efficiency and allowing a reduction in size of the
acoustical horn.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a portable radio pager in
accordance with this invention;
FIG. 2 is a section view of the pager of FIG. 1 along the section
lines AA', showing the circuit board and components of the
removable radio receiver mounted in the pager housing;
FIG. 3 is a view of the portable radio receiver chassis, including
the transducer adapted to be mounted in the pager housing shown in
FIG. 1;
FIG. 4 is a perspective view of the housing shown in FIG. 1 with
the U-shaped front and rear cover and removable radio receiver
chassis removed;
FIG. 5 is a cross-sectional view of the housing in FIG. 4 along the
section lines 5--5;
FIG. 6 is a perspective exploded view of the pager housing with the
rear cover and the portable radio receiver chassis removed and one
side wall exploded to expose the acoustical horn;
FIG. 7 is a side view of the housing of FIG. 6 with the side wall
removed to expose the acoustical horn;
FIG. 8 is a perspective view of the acoustical chamber located in
the housing of FIG. 4;
FIG. 9 is a perspective view of the coupling device in the housing
of FIG. 4; and
FIG. 10 is a perspective view of the transducer device shown in
FIG. 3 with its cover removed.
DETAILED DESCRIPTION
The radio apparatus of the invention is shown in FIG. 1 and is
illustrated as a radio pager, it being understood that other
devices, such as transceivers may employ the features of this
invention. A rectangular elongated housing 10 includes a first
rectangular elongated compartment 11 and a second rectangular
elongated compartment 12 adjacent the first compartment 11.
Compartment 11 contains a self-contained removable radio receiver
chassis, and compartment 12 contains a hyperbolic acoustical horn.
Compartments 11 and 12 are separated by an interior partition wall
18, shown in FIG. 4. Top wall 13 has an aperture 14 therein through
which extends switch 15 on the radio receiver. A second aperture 17
in top wall 13 is the output opening for the hyperbolic acoustical
horn. A grill cloth 16 covers aperture 17, preventing dirt or
foreign matter from entering the acoustical horn. Clip 19, secured
to back wall 20 of compartment 11 in housing 10, allows the radio
pager to be secured in a user's shirt pocket or on the user's
belt.
Referring to FIGS. 2 and 3 the portable radio receiver chassis for
the pager is shown. Printed circuit board 25 seats in the first
compartment 11 of housing 10. Switch 15 is mounted thereon and
extends through aperture 15 in top wall 13. A number of components
26 representative of the entire radio circuitry for the radio
receiver chassis are shown on printed circuit board 25. A battery
27 is secured in battery holder 28 on printed circuit board 25, and
provides the power necessary for operating the radio receiver.
Transducer device 29 is also secured to printed circuit board 25,
and converts the received demodulated signals to audio signals,
thus providing an entirely self-contained portable radio
receiver.
Referring to FIG. 10 there is shown transducer device 29 with
housing cover 31 removed. The transducer 35 is located beneath the
structure shown and directly below aperture 36. Sound waves
developed by transducer 35 are coupled through the spiral passage
shown at 32 and emitted at aperture 30. The audio signals are
emitted from output aperture 30 in transducer housing cover 31 as
sound waves. These sound waves are coupled via a coupling device
33, (shown in position in FIGS. 2 and 9) to an acoustical chamber
34 secured to an inner wall of housing 10.
Referring to FIG. 4, the acoustical chamber 34 is more clearly
shown. Chamber 34 is secured, adjacent top wall 13, to rear wall 37
in compartment 11 and to interior partition wall 18, which
separates compartments 11 and 12. The acoustical chamber 34 has a
first aperture 38 in the top surface thereof. Coupling device 33 is
seated in aperture 38, and held in place by the aperture side
walls. Coupling device 33 is a resilient cylindrical member, which
has an outer wall 40, and an aperture 41, axially extending through
the cylinder. Circumferential groove 42 is cut in outer wall 40 of
coupling device 33, adjacent end 43. The side walls of aperture 38
on acoustical chamber 34 are inserted into groove 42 for securing
coupling device 33 to chamber 34. Coupling device 33 may be
manufactured from rubber or a synthetic equivalent of rubber.
Referring again to FIG. 2, output aperture 30 of transducer device
29 is positioned adjacent aperture 41 in coupling device 33. When
circuit board 25 is inserted into compartment 11, coupling device
33 is compressed, with end 43 bearing against transducer housing
cover 31 and surrounding output aperture 30. Coupling device 33
acts to couple the sound waves from output aperture 30 of
transducer device 29 to acoustical chamber 34. Because coupling
device 33 only resiliently bears against transducer housing 31, the
portable radio receiver may be removed and reinserted in housing
10, and when reinserted will make a good acoustical connection with
acoustical chamber 34. This allows printed circuit board 25, and
the entire self-contained radio receiver mounted thereon, to be
removed, tested and easily reinserted; or to be inserted in a
number of housings having different types of acoustical horns.
Referring to FIG. 8, sound waves developed by transducer device 29
are coupled through coupling device 33 to aperture 38 in acoustical
horn 34. A spiral conduit 43 conducts the sound waves to a second
or output aperture 44 of transducer device 29. Referring to FIGS. 6
and 7 the sound waves are coupled from output aperture 44 in
acoustical chamber 34 through aperture 45 in inner partition wall
18, to the hyperbolic acoustical horn located in compartment 12.
Acoustical chamber 34 acts to match the output characteristics of
transducer device 29 to the acoustical horn and couple the sound
waves from transducer device 29 to the acoustical horn, while
providing an isolation between the compartments.
Referring to FIGS. 5, 6 and 7, the hyperbolic acoustical horn
located in compartment 12 consists of a first portion 50 extending
downwardly from a position adjacent top wall 13, a second portion
51 extending upwardly from bottom wall 52 to top wall 13, and a
curved portion 53 connecting the first portion 50 and the second
portion 51. As can be seen by reference to FIGS. 5, 6 and 7 the
area of the cross-section of the horn expands hyperbolically along
its axis starting at aperture 45. Sound waves entering aperture 45
strike a curved section 55 of side wall 56 and curve around into
first portion 50. The sound waves are amplified in portions 50, 51
and 53 and are emitted at aperture 17 in top wall 13. The
hyperbolic horn in compartment 12 of the preferred embodiment is
approximately nine inches long. A nine inch long hyperbolic horn
has an acoustical primary resonance at approximately 2,000 cycles
and an acoustical reflection resonant frequency response at
approximately 700 cycles. These resonances produce an enhancement
of the sound waves in the audio, and particularly in the speech
frequency range so that the sound level emitted from aperture 17 is
substantially greater than normally associated with horns having
such small physical dimensions. Because aperture 17 of the horn is
located in top wall 13, the audio signals are directed towards,
rather than away from the user.
As can be seen, an improved portable radio apparatus has been
provided including a housing having an integral acoustical horn.
The portable radio receiver chassis is self-contained and operable
when removed from the housing. Removal from and insertion into the
housing can be easily accomplished without the necessity for
special mechanical interconnecting devices between the acoustical
horn and receiver because of the use of a resilient acoustical
coupling device. The acoustical horn because of its length, its
hyperbolic characteristic and resonance produces a greater sound
level than normally associated with such small physical dimensions.
An acoustical chamber is used to match the transducer device output
to the acoustical horn while providing isolation between the
compartments.
* * * * *