Electronic flea repelling device with means for carrying collar strap behind the device housing

Fleas are repelled from a four-legged animal by compressional waves derived from an electric-compressional wave transducer driven by electronic circuitry powered by a battery. The battery, circuitry and transducer are mounted in a housing carried by a collar around the neck of the animal. The housing includes a first face having an aperture covered by a dust screen. A face of the transducer positioned behind the dust screen radiates compressional wave energy through the dust screen that is reflected from the ground beneath the animal back to the underneath portions of the animal. The duty cycle and frequency of ultrasonic pulses derived by the transducer cause the fleas to be repelled. A second face, opposite from the first face, abuts against the body of the animal and carries a frangible, spring-like plate having a pair of slots through which the collar extends. The plate spring properties and the frictional force of the strap in the slots maintain the housing in situ on the neck of the animal, so the compressional waves are directed to the ground. If the animal becomes trapped by the housing, the plate breaks between the slot and an edge of the plate in response to the animal tugging on the trapping agent to enable the animal to escape.

TECHNICAL FIELD 
The present invention relates generally to portable electronic devices 
mounted on four-legged animals for emitting compressional waves that repel 
fleas from the animal, and more particularly, to an improved structure for 
mounting a housing containing such a device so that the strap is secured 
to the housing against a face of the housing that bears against the body 
of the animal. 
BACKGROUND ART 
There is disclosed in the copending, commonly assigned application Ser. No. 
742,232, filed June 7, 1985 now U.S. Pat. No. 4,669,424 an apparatus for 
repelling fleas from the body of domestic animals, such as dogs and cats. 
The prior art structure includes a housing containing battery means to 
energize a low duty cycle relaxation oscillator for gating on an 
ultrasonic oscillator. Oscillations derived by the ultrasonic oscillator 
drive an electric-compressional wave transducer. The duty cycle and 
frequency of the relaxation oscillator and the ultrasonic frequency are 
arranged to repel fleas from a region irradiated by the ultrasonic 
compressional waves. 
The housing containing the battery, electronic circuitry and transducer is 
mounted on the animal by a collar strap. The housing is mounted on the 
collar strap so that the compressional waves derived by a radiating face 
of the transducer are directed downwardly, toward a surface beneath the 
animal. The compressional waves are reflected from the surface to the 
underneath parts of the animal. The compressional wave energy incident on 
the underneath parts of the animal has sufficient intensity to prevent 
fleas from climbing onto the animal and to drive fleas on the animal from 
it. For effective operation it is important for the transducer radiating 
face to face toward the surface beneath the animal. 
The prior art housing contains a pair of fixed appendages extending to 
opposite sides of a central, main part of the housing. Each of the 
appendages includes a slot through which the collar extends, whereby the 
collar has a tendency, in certain instances, to slip about the neck of the 
animal when the housing and strap are secured to the animal by a buckle on 
the strap. In certain instances, the housing slips around the neck of the 
animal to such an extent that the compressional wave energy emitted by the 
transducer is not incident on the surface beneath the vicinity of the 
animal. Thereby, the intensity of the compressional wave radiant energy 
incident on the underneath parts of the animal is severely reduced and, in 
some instances, does not enable the fleas to be repelled from the animal. 
Another problem that has been from time to time encountered with the prior 
art electronic flea repelling collar is that the housing gets hung up on 
obstacles, to cause the animal carrying the collar to be trapped. The 
problem is particularly applicable to small dogs and cats in which the 
housing extends beyond the perimeter of the neck of the animal. It can 
result in entrapment for prolonged durations, until the animal can be 
located and released. 
It is, accordingly, an object of the present invention to provide a new and 
improved arrangement for mounting a housing containing a pulsed ultrasonic 
frequency compressional wave flea repelling structure on a collar strap 
adapted to be placed around the neck of an animal to be protected from 
fleas in such a manner that the housing remains in situ on the animal neck 
at the location where it was originally placed by an installer. 
Another object of the invention is to provide a new and improved structure 
for mounting a housing for a compressional wave source that repels fleas 
from the vicinity of an animal being protected, wherein the housing is 
mounted on the animal at a fixed position that is not easily changed to 
enable the compressional wave energy to be reflected from the ground 
beneath the animal. 
A further object of the invention is to provide a new and improved 
structure for mounting a housing for a compressional wave source that 
repels fleas from the vicinity of an animal being protected, wherein the 
housing is mounted on the animal in such a way that the animal can free 
itself if it becomes entrapped by the housing hanging up on an 
obstruction. 
DISCLOSURE OF INVENTION 
In accordance with one aspect of the present invention, an improved 
apparatus for repelling fleas from a four-legged animal comprises a 
housing containing an electric-compressional wave transducer and 
electronic semiconductor circuitry powered by a battery. The circuitry 
derives periodic relatively low duty cycle pulses of electric energy that 
gate on an ultrasonic carrier frequency. The transducer has a radiating 
face for deriving a compressional wave replica of the periodic pulses and 
the ultrasonic carrier frequency. The duty cycle and frequency of the 
pulses and the carrier frequency are selected such that the compressional 
wave replica repels fleas from a region irradiated by the compressional 
wave energy. The housing includes a first face having an aperture covered 
by a dust screen. The transducer radiating face is positioned behind the 
dust screen so that compressional wave energy radiated from the transducer 
passes through the dust screen. The housing includes a second face 
opposite from the first face. Fixedly mounted on the second face is a 
means for receiving a collar strap adapted to extend around the neck of 
the animal. The strap receiving means, being mounted on the second face, 
substantially prevents the housing from slipping about the collar strap. 
The arrangement of the strap, strap receiving means and housing is such 
that the housing stays in situ on the neck of the animal so that the 
radiating face is pointed toward the surface beneath the animal and the 
compressional wave energy is reflected from the surface beneath the animal 
back toward the animal to repel fleas from the animal. 
In a preferred embodiment of the invention, the strap receiving means 
includes a spring-like, elastic plate fixedly mounted on the second face. 
The plate includes a pair of slots approximately equally disposed on 
opposite sides of a center line of the second face, between end walls of 
the housing. The plate is preferably made of plastic and secured to the 
second housing face by any suitable means, such as screws extending 
through the plastic plate into the housing second face. 
It has been found that the stated arrangement enables the housing to remain 
in situ, at the same position where the housing was originally placed on 
the collar during installation. Because the collar strap is secured in 
place on the second or back face of the housing and the spring effect of 
the plate, frictional forces hold the strap and housing in place against 
the neck of the animal. In addition, the material of the plate and the 
relative width of the strap and the length of the slots are such that 
there is relatively great adhesive, frictional force between the strap and 
the plate; in one preferred embodiment, the plate is formed of 
polyethylene and the strap is woven fabric. 
The plate, being formed of polyethylene or some other frangible material, 
is broken if the animal becomes trapped by the housing being hung up on an 
obstacle. The plate is broken between the slot and an edge of the plate in 
response to the animal tugging on the collar and housing as he pulls away 
from the obstacle. When the plate breaks the housing is free to turn about 
the collar strap and the animal is freed from the obstacle. The elastic 
properties of the plate enable the housing to conform with the necks of 
pets having diverse perimeter lengths.

BEST MODE FOR CARRYING OUT THE INVENTION 
Reference is now made to FIG. 1 of the drawing wherein dog 1 is illustrated 
as including a woven, nylon fabric neck collar strap 2 on which s mounted 
housing 21. Contained in housing 21 are an ultrasonic electric signal to 
compressional wave transducer 15, in the form of a piezo electric crystal. 
Transducer 15 is driven by electronic circuitry contained in housing 21 
and powered by a lithium dry cell battery also contained in the housing. 
Housing 21 is placed on collar strap 2 around the neck of dog 1 so that 
ultrasonic compressional waves derived from the emitting face of 
transducer 15 are directed downwardly away from the dog. The ultrasonic 
compressional waves are directed in a wide angle beam toward surface 5 on 
which dog 1 is standing, sitting or lying. 
The energy in the compressional wave beam derived from transducer 15 is 
reflected from surface 5 on which dog 1 is located so that the angle of 
incidence of the beam impinging on surface 5 is equal to the angle of 
reflection. Thereby, the ultrasonic compressional wave energy reflected 
from surface 5 is incident on virtually all of the under parts 6 of dog 1. 
In one specific embodiment an effective coverage area has a total length 
of approximately eight feet, with the center of the area of coverage being 
approximately directly below housing 21. By reflecting the energy of 
transducer 15 from surface 5, a large coverage area consistent with the 
under parts of dog 1 is conveniently provided. 
The reflected ultrasonic compressional wave energy incident on dog 1 is 
preferably pulsed at a rate in the audio range of 20 to 300 cycles per 
second with a relatively low duty cycle of less than 50%, preferably in 
the range of about 2% to 30%. Each compressional wave pulse derived from 
transducer 15 has a single ultrasonic frequency, preferably in the 35 
KHz-45 KHz range. In tests that have actually been performed these 
parameters have been found to be effective in repelling fleas and other 
similar creatures from a very high percentage of dogs who have had the 
device within housing 21 applied to them. 
If the pulse rate is less than about 20 cycles per second, the pest 
repulsion rate decreases considerably. Also, a pulse rate of less than 20 
Hz is not generally perceivable to the human ear to prevent aural 
techniques from being used to test whether a circuit is operating. The 
pulsed low duty cycle variations considerably add to the effectiveness of 
the device in repelling these objectionable pests relative to continuous 
wave energy. If the duty cycle drops below about 2%, the pest repulsion 
effectiveness falls virtually to zero. The low duty cycle also reduces the 
power requirements for the electronic circuitry in housing 21 that drives 
transducer 15. The 35 KHz-45 KHz frequency range is above the range which 
can be perceived by the ears of domestic animals, such as dogs and cats, 
so that the animal is not annoyed by the ultrasonic compressional wave 
energy emitted by transducer 15. While the power emitted from transducer 
15 and reflected back to dog 1 is not adequate to kill the pests on the 
dog, it is sufficient to repel the pests from the dog. The pests can be 
killed only if approximately 500 milliamperes are supplied to the 
electronic circuitry which powers transducer 15. This is not a practical 
current dissipation level for a portable battery-powered product, such as 
must be included in housing 21, for effective use over a several month 
period. 
A human can easily perceive whether the electronic circuitry in housing 21 
is properly operating and whether the battery energizing the electronic 
circuit which drive transducer 15 has sufficient power to repel the pests 
on dog 1. The audio frequency tone derived from transducer 15 can be heard 
by the vast majority (approximately 85%) of humans if the transducer is 
placed between 3 and 6 inches from the human ear. Thereby, the vast 
majority of humans can conveniently detect if the electronic circuitry in 
housing 21 is properly activating transducer 15. 
The intensity level of the ultrasonic compressional wave energy derived by 
transducer 15 is selectively, inferentially determined as being adequate 
since a light source, in the form of light emitting diode 9, is mounted in 
housing 21. If the batteries powering the electronic circuitry which 
drives transducer 15 has adequate power to provide the pest repulsion 
function, light emitting diode 9 is energized when spring biased push 
button switch 18 on the top face of housing 21 is pressed downwardly to a 
test position from a normal position where the battery power supply in the 
case is disconnected from the diode. If, however, the battery does not 
have adequate energy to provide the repulsion function, activation of 
switch 18 to the test position does not result in energization of light 
emitting diode 9 and the human is advised that it is necessary to replace 
the battery. 
Reference is now made to FIGS. 2-6 wherein housing 21 for the electronic 
flea repeller in accordance with the present invention is illustrated, in 
combination with polyethylene plate 22 through which woven, nylon fabric 
collar strap 2 extends. Housing 21, plate 22 and collar strap 2 are 
fabricated in such a manner as to maintain the housing in situ on the neck 
of dog 1 so that the ultrasonic compressional wave energy is almost 
invariably directed toward the surface beneath the animal. As discussed 
supra, the prior art device was constructed in such a manner that there 
was a tendency, in certain instances, for the housing containing the 
device to turn on the neck of the animal. When the housing turned on the 
neck of the animal, the compressional wave energy was not directed toward 
the surface beneath the ground and the effectiveness of the device was 
considerably reduced. 
Housing 21, preferably constructed of an electrically insulating, molded 
plastic material formed basically as a right parallelepiped, includes 
parallel top and bottom faces 23 and 24 with slightly tapered end walls 25 
and slightly tapered side walls 26. Walls 25 and 26 are tapered inwardly 
as they extend from face 24 toward face 23 so that the area of face 23 is 
slightly less than that of face 24. Walls 25 and 26 have slight outwardly 
tapered segments 27 abutting against face 24. This shape of housing 21 is 
aesthetically pleasing and provides a snug fit of the housing on the 
animal. The entire device has a volume of about 1 cubic inch in a typical 
embodiment, having a length of about 2 inches, a width of about 1 and 
one-eighth inch and a height of about one-half inch. Thereby, the device 
easily is carried by any domestic animal, from a very small dog or cat, to 
a large dog. Plastic, preferably polyethylene, spring-like, elastic plate 
22 is fixedly secured to face 24 by screws 28 which are threaded into 
threaded bores in posts 61 that are equidistant between the end walls 25 
of housing 21. 
As illustrated in FIG. 6, strap 2 extends between the face of plate 22 that 
abuts against face 24 between end walls 25 and slots 31. Strap 2 is 
threaded through slots 31 from the region between the surfaces of plate 22 
and face 24 that abut against each other when the strap is not in situ. 
Strap 2 is sandwiched between plate 22 and face 24 in the portion of the 
plate outboard of slots 31, so opposite faces of the strap abut against 
portions of face 24 and plate 22 outboard of slots 31. Strap 2 extends 
beneath plate 22 so that the upper face of the strap abuts against the 
lower face of the plate. 
Opposite ends of strap 2 are secured together by conventional buckle 
fastener 41, of the type including a metal plate with a pair of slots. 
Buckle 41 positions strap 2 and housing 21 on the neck of dog 1 so housing 
21 is positioned at the bottom of the neck of dog 1 to direct 
compressional wave energy toward the surface beneath the dog. 
In use, collar strap 2 is pulled through buckle 41 so that the collar is 
somewhat tight around the neck of the dog. The neck of the dog exerts a 
force against the face of plate 22 remote from housing 21 to urge the end 
portions of the plate against the face of strap 2 proximate thereto. 
Thereby, opposite faces of strap 2 abut against face 24 and the face of 
plate 22 outboard of slots 31. The elastic properties of flexible plate 22 
urge strap 2 against face 24 to assist in holding housing 21 in situ 
against the neck of dog 1. The direct application of force by the neck of 
the dog against plate 22 and the elastic properties of the plate hold 
housing 21 in situ on strap 2. The width of strap 2 relative to the length 
of slots 31, the thickness of the strap relative to the width of slots 31 
and the adhesive nature of the woven nylon strap against polyethylene 
plate 22 provide additional frictional forces to assist in holding housing 
21 in place on the strap. It has been found through actual tests that the 
tendency for the housing to turn about collar strap 2 is virtually 
obviated with the described and illustrated construction. 
The specific construction of plate 22 and its relationship to housing 21 
are such that collar strap 2 holds the housing in situ on many different 
size dogs. In large dogs, plate 22 basically stays in place and the 
described abutting relation between plate 22, strap 2 and face 4 occurs. 
For small dogs and cats, plate 22 bends longitudinally in the vicinity of 
end walls 25 but retains the abutting relation in the vicinity of slots 
31. 
On top face 23 of housing 21 is circular aperture 42 behind which are 
fixedly mounted dust screen 43 and cone 40, fixedly mounted on a piezo 
electric crystal which functions as electric-compressional wave transducer 
15. Dust screen 43 is preferably a metal grid with apertures between 
adjacent strands of metal disposed at right angles to each other, in a 
conventional manner. To prevent dislodgement of dust screen 43, the wall 
comprising face 23 includes four radially extending arms 45 at mutual 
right angles to each other. Arms 45 terminate at ring 46, concentric with 
the circular perimeter of aperture 42 in the wall forming face 23. Arms 45 
and ring 46 protect dust screen 44, cone 40 and transducer 15 from 
external factors which might tend to damage them; exemplary of such 
factors is the paw of the dog attempting to scratch housing 21. Aperture 
43 and the components mounted behind it are located toward one end wall 25 
of housing 21. 
Light emitting diode (LED) 9 includes an envelope fixedly positioned in an 
aperture in the wall comprising top face 23. Light emitting diode 9 is 
connected via suitable leads to printed circuit board 64 located in 
housing 21. Printed circuit board 64 carries electronic components 
including relaxation oscillator 61 (FIG. 7) for deriving electric pulses 
that gate 40 KHz ultrasonic oscillator 62 on at at a frequency in the 
range of 20-300 Hz with a duty cycle in the range of 2%-30%. Oscillator 62 
activates driver 63 for transducer 15. 
There is a tendency for housing 21 to be hung up on obstacles, to cause 
small animals carrying the housing to be trapped. The problem is most 
noticeable in dogs and cats in which the housing extends beyond the 
perimeter of the neck of the animal. If the animal is so trapped, it tugs 
on collar 2 and eventually breaks frangible plate 22, usually between one 
of slots 31 and the adjacent end or side edge of the plate. When plate 22 
is broken, housing 21 turns on collar 2 so that the animal is able to free 
itself from the obstruction. Generally, housing 21 stays on collar strap 2 
after plate 22 has been broken so that the housing is not lost. A new 
plate is easily installed by the owner of the animal to enable the flea 
repeller to be returned to service. 
Battery 65 in housing 21 powers electronic circuitry of board 64, 
transducer 15 and LED 9. To determine if battery 65 has sufficient energy 
to power the circuitry properly, light emitting diode 9 is activated to 
produce a visual signal in response to spring biased normally open switch 
51 being activated to a closed position by a human operator pressing 
elastic membrane 52. Membrane 52 covers aperture 53 in the wall including 
face 23 and has an upper face that is slightly above face 23; the 
thickness of membrane 52 is slightly exaggerated in the drawing. The 
underneath face of membrane 52 carries metal ring contact 54. Ring contact 
54 is a spring that biases membrane 52 in an upward position, so that 
contact 54 is normally spaced from stationary, metal disk contact 55, 
fixedly positioned in housing 21 just below ring contact 54. In response 
to membrane 52 being depressed by an operator desirous of determining the 
condition of battery 65, contacts 54 and 55 engage each other. As soon as 
membrane 52 is released, the spring force of ring contact 54 against the 
underneath side of membrane 52 causes the membrane to snap upwardly, as 
illustrated in FIG. 3, so that contacts 54 and 55 become open circuited. 
Contacts 54 and 55 are connected to circuit components on the integrated 
circuit, and to light emitting diode 9 so that the diode becomes 
illuminated in response to contacts 54 and 55 engaging each other if the 
voltage of the battery is adequate to enable sufficient compressional wave 
energy to be derived from the speaker for the flea repelling function. 
While there has been described and illustrated one specific embodiment of 
the invention, it will be clear that variations in the details of the 
embodiment specifically illustrated and described may be made without 
departing from the true spirit and scope of the invention as defined in 
the appended claims.