ELECTRONIC PEST REPELLING APPARATUS AND METHOD

Abstract: Portable pest repellant apparatus and methods, which is designed to be worn by an animal. A high frequency crystal speaker (15) having a relatively narrow operating band is provided with a signal which is generated by the speaker and, therefore, requires little energy to output sound at its nominal frequency. A pulsing circuit (11) is provided which pulses the output of the speaker (15) in such a manner that pest are equally annoyed and therefore repelled as if the sound was continuous.

Description: ELECTRONIC PEST REPELLING APPARATUS AND METHOD BACKGROUND OF THE INVENTION 1. Field of the invention This invention is related in general to the field of ultrasonic sound pest repellers and in particular to the field of apparatus which may be attached to an animal for purposes of ridding the animal of parasitic pests by the use of ultrasonic sound. 2. Description of the Prior Art Sound waves comprise energy that is propagated by air. As a point of reference, the energy comprising radio waves does not rely on air or propagation of travel from one point to another. Ultrasonic energy, or ultrasound, is energy having a frequency that is above the level which can be heard by the human ear. It may, however, be perceived by other animals. A familiar example is a dog whistle which can be heard by a dog but not by humans. Sometime ago, studies seemed to indicate that ultrasonic energy having a sufficiently high intensity would discourage certain insects, rodents or other pests from being present in a particular area. In accordance with these studies, apparatus was quickly developed in an attempt to drive pests away from locations where the pests were considered a health hazard and/or caused high financial losses such as, for example, grain elevators, and to prevent them from reentering the same. After an initial period of great anticipation accompanied by somewhat widespread use of the apparatus, mixed feelings about the actual success of such apparatus began to exist. The apparatus never really obtained the anticipated success and, subsequently, the idea of ultrasound to eliminate pests fell out of favor and the apparatus employing the idea was little used. There have been occasions of revival of the use of ultrasonic energy in such situations, but due to lack of any significant success, the devices are virtually no longer being used. A close examination of the propagation of ultrasonic energy explains, in part, some of the reasons for the generally poor experience with ultrasonic pest repelling devices. Sound waves decrease in intensity with the square of the distance over which they travel. This means that every time the distance is doubled, the intensity decreases four times. Thus, with the reference point of one foot, the intensity of the sound waves will be one-fourth of the reference at a distance of two feet, one-sixteenth of the reference at a distance of four feet, one sixty-fourth of the reference at a distance of eight feet, one two-hundred-fifty-sixth of the reference at a distance of sixteen feet, and one one-thousand-twenty- fourth of the reference at a distance of thirty-two feet. Therefore, if ultrasound apparatus can emit enough sound to repel pests at a distance of one foot, it would need to generate over* o'ne thousand times as much energy to have the same effect approximately thirty-two feet from the apparatus. It can be seen, therefore, that for a device to effectively operate over a large distance, a relatively high amount of power is necessary to generate the required amount of ultrasonic energy. Where size and space of the apparatus are constraints as with the present end use, the ultrasonic devices of the prior art are unsatisfactory. Accordingly, it is a object of the present invention to provide ultrasonic apparatus which is small in size and weight but yet is sufficiently powered to produce ultra¬ sonic sound over a distance consistent with its end use such as the length of the body of an animal to which is to be applied. Ultrasonic sound tends to penetrate soft objects such as curtains, but is reflected by hard objects such as tables. Ultrasonic sound, therefore, is absorbed by soft objects and casts a "sonic shadow" behind hard objects. These directional aspects of ultrasonic sound comprise deficiencies in the prior art ultrasound stationary devices. Because of the myriad, and varying environments within which ultrasound devices must function, it is understandable that the prior art devices do not function adequately. Where such prior art devices seem to adequately operate are mere happenchance. An object of the present invention is, therefore, to provide an ultrasound device which functions regardless varying environmental conditions. Still another deficiency of the prior art ultrasound devices comprises a physical size of the devices. In order to cover large areas, high power is required. High power necessitated relatively large devices. A large device would obviously be unsatisfactory _ as applied to a pet or other domestic animal. Another object of the present invention is, therefore, to provide an effective ultrasound device which is of a small size so that it may be easily worn upon the body of a small domestic animal. In conjunction with this object, there exists another object which comprises providing such a device with minimal power requirements so that a small battery may adequately power such a device. There are, of course, other objects of the present invention which although not specifically stated will be apparent to those ordinarily skilled in the art to which this invention pertains, and which other objects are intended to be included within the scope of the presently- disclosed invention. SUMMARY OF THE INVENTION The above-stated objects, as well as others, are achieved by the present invention which comprises an electronically-operated device which may be worn upon the neck of a domestic animal and which utilizes ultrasound to rid the domestic of annoying fleas, ticks, and other similar pests. A battery-powered electronic circuit in conjunction with a high frequency speaker are enclosed within a housing which may be attached by an appropriate strap to the neck of a domestic animal. The direct current power from the battery is uniquely converted into alternating current by a switching inverter circuit. A unique electronic switch is used with the electronic circuit such that the ultrasound produced by the device is pulsed between fifty and one hundred and fifty pulses per second. Pulsing the output of the device serves to lower power requirements while providing high frequency sound which creates an unpleasant environment for the pests resulting in their leaving and being repelled from the immediate vicinity of the domestic animal. New and novel means are provided in the inventive device which further results in compactness of size, minimal power requirements and simplicity of design. A relatively ordinary speaker which operates efficiently over a very narrow range of frequencies is employed to further minimize power requirements. In order to generate the required frequency within the narrow range at which the speaker is efficient, the speaker itself is used to generate the required narrow band of frequencies. In other words, a self-resonant circuit is provided wherein the speaker is used to generate the same narrow band of frequencies which the speaker requires in order to emit sound. Furthermore, this is accomplished without the need of a classical high-stability circuit. The inventive circuit separates the feedback path from the current path in a crystal oscillated circuit used in a self-oscillating mode. The current path is from an inverter through the transducer or speaker, then through a resistor which is connected to ground. The feedback path is from the inverter through the transducer or speaker, but instead of going through the resistor, the feedback flows through a capacitor to another inverter connected in series to the first inverter. A resistor between the capacitor and the first and second inverters allows a split of current for the two paths. The circuit thereby develops a self- sustaining oscillation at the characteristic frequency of the transducer (or speaker) . And, since there is a current path from the inverter through the speaker and through the resistor to ground, the speaker will deliver sound output. Various other objects, advantages and features of the invention will become apparent to those skilled in the art from the following discussion taken in conjunction with the following drawings, in which: BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 comprises a schematic circuit diagram illustrating the novel circuitry of the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference is now made to the drawing which illustrates the inventive circuitry of the pest repellent apparatus. One portion of the inventive circuitry comprises the ultrasonic sound producing loop 10, while another portion thereof comprises a pulsing loop 11. A source of power which preferably comprises a DC battery 12 is commonly connected at one side thereof to loops 10 and 11 with the other side, being connected to ground. The use of a battery power supply 12 allows the pest repellent apparatus to be portable. portability is, of course, necessary so that the animal to which the pest repellent apparatus is connected may be free to travel without restriction as such animal would normally travel when the pest repellent apparatus is not connected to its body. Loop 10 comprises a pair of series connected inverters 13 and 14 and ultrasonic speaker 15. Speaker 15 preferably comprises a high-efficiency piezoelectric or crystal speaker which emits sound above the threshold sound levels capable of being heard by the animal to the which the pest repellent apparatus is to be attached. Accordingly, such frequency may be of the order of thirty thousand (30,000 Hz) Hertz to forty thousand (40,000 Hz) hertz or cycles per second. A nominal frequency of approximately thirty-eight thousand (38,000 Hz) hertz has been found to be acceptable for use with most domestic animals such as dogs and cats. Furthermore, such frequency has been found to be quite unpleasant to small insects such as fleas or ticks. It is to be noted that the inventive apparatus is not to be limited to sound frequencies between thirty thousand and forty thousand hertz, nor any particular value therebetween. Any high frequency may be employed provided the sound is not detrimental to man or to animals, utilizing the apparatus but is annoying and unpleasant to the insect or insects which are to be repelled from the animal and the immediate vicinity thereof. Speaker 15 has been chosen to comprise a high efficiency ultrasonic piezoelectric speaker which operates efficiently only over a relatively narrow band of frequencies on either side of its nominal rating. This type of speaker requires very little power to operate as compared to a wide range speaker which would be unacceptable in the inventive application because of the high power requirements of such a speaker. High power requirements would unacceptably increase the size of the battery or alternatively, unacceptably decrease the operating lifetime of the battery. A high-powered battery, capable of operating over a reasonable lifetime, for example, six months, would be to heavy to be comfortably worn by the animal using the device. A high efficiency, narrow sound band speaker on the other hand, produces an acceptable level of sound only within the narrow operating band. The frequency of the signal input to speaker 15 must, therefore, be within the same narrow operating band in order to conserve energy. Loop 10 of the inventive circuitry provides speaker 15 with such a signal within the narrow band of its operating frequencies. The signal produced within loop 10 of the inventive circuitry is accomplished by allowing the speaker 15 itself to generate the required signal. Speaker 15 in conjunction with converter 14 allows speaker 15 to operate as a crystal which resonates at its own required frequency. In this regard, in the drawing, speaker 15 is shown as a combination speaker and crystal. In order to precisely match the resonating frequency with the frequency of sound efficiently output by speaker 15, both the current path and the feedback path are arranged to pass through the crystal of speaker 15. In this manner, speaker 15 when operating as a crystal, and speaker 15 when operating as a speaker, receive exactly the same current. Speaker 15, therefore, receives the exact signal at which it most efficiently operates, and, therefore, emits a strong or powerful sound. The current path in loop 10 of the inventive circuitry comprises the path described by inverter 14, the crystal within speaker 15, resistor 16, and then to ground. The feedback path is from inverter 13 through inverter 14, through the crystal within speaker 15, through capacitor 17, and back to inverter 13. This circuitry operates as follows. When power is applied through power supply 12, both inverters 13 and 14 output a low signal. This causes inverter 13 to invert the signal to a high level with a very fast rise time. The crystal within speaker 15 experiences this as a pulse containing a broad spectrum of frequencies including its nominal frequency. Since the crystal within speaker 15 is sharply tuned high Q transducer, it reacts only to its nominal frequency and draws power through resistor 16 to ground. There will be a voltage developed across resistor 16 which will be of the nominal frequency of the crystal of speaker 15. Since the voltage at junction 18 and resistor 16 is rapidly moving at the nominal frequency of the crystal within speaker 15, there will also be a voltage developed across capacitor 17. The voltage at junction 19 and resistor 20 will be proportional to the value of resistor 20 and the impedance of capacitor 17 at the nominal frequency of the crystal within speaker 15. When the voltage rises to the threshold of inverter 13, the voltage at the junction 21 will become positive and the process will repeat itself in the opposite direction. Continued operation, therefore, develops a self-sustaining oscillation at the nominal frequency of the crystal of speaker 15. And, since there is a current path from inverter 14 through speaker 15, through resistor 16 and to ground, speaker 15 will output sound at its nominal frequency and at a level which can be heard by the insects which it is designed to repel. Another capacitor 22 is connected to loop 10 to ground as shown in the drawing. Capacitor 22 is used because the crystal aspects of speaker 15 is not a perfect or ideal crystal and, therefore, a compensating capacitor is required to overcome this minor deficiency. It is to be noted that the circuitry provided within loop 10, accomplishes the unique result of utilizing speaker 15 to both generate its nominal c frequency and output sound at this nominal frequency. Furthermore, this result has been obtained without the need of a high precision circuit requiring numerous additional components which normally would be required to provide the same stability accomplished by the inventive circuit. Also, the additional components would require more power to operate which then would result in the above-noted attendant deficiencies comprising a shortened life span and/or unacceptable weight. The high-frequency sound output by loop 10 of the inventive circuit comprises steady-state ultrasonic energy of the. s-ame frequency. Loop 11, as shown in the drawing, modifies this steady-state sonic energy by causing the output frequency to be pulsed. Loop 11 comprises an electronic switch 23 of a type which is well known in the art, such as a astable multivibrator or oscillator. The pulsing by switch 23 is in accordance with the time constant provided by the combination of resistor 24 and capacitor 25, which is also well known in the art. Loop 11 thus operates to cause the sound output by loop 10 to be pulsed in a wave form from a zero value to a maximum power value and then back to zero again, with this cycle repeating itself a number of times or pulses per second. In a preferred embodiment of the invention, the electronic switch 23, resistor 24, and capacitor 25 are arranged to pulse the sound output by speaker 15, from approximately 50 to 150 pulses per second, with the ratio of the time that the sound is on to the sound off being approximately one- to-ten. It has been found that this unique arrangement has the effect of repelling pests from an animal substantially as effective as an unpulsed or continuous high-frequency sound. There is, however, a decided advantage of pulsed sound. No energy is being consumed during the period of time when no sound is output. Thus, a relatively small battery or DC power source may be used while a reasonably long operating lifetime of the pest repelling apparatus, for example, six months, may be achieved. Lightweight with a corresponding reasonably long operating lifetime are considered essential to a successful pest repelling device. While the invention has been described, disclosed, illustrated and shown in certain terms or certain embodiments or modifications which is has assumed in practice, the scope of the invention is not intended to be nor should it be deemed to be limited thereby and such other modifications or embodiments as may be suggested by the teachings herein are particularly reserved especially as they fall within the breadth and scope of the claims here appended.

Claims: I claim as my invention: 1. Apparatus for repelling pests from the body of an animal comprising a source of DC power, an ultrasonic crystal speaker connected to said power source, means for generating a signal by said speaker at substantially the nominal frequency of said speaker, means for inputting said generated signal into said speaker, and means for pulsing the output sound of said speaker. 2. The apparatus of claim 1, wherein said means for generating said nominal frequency signal comprises a current path comprising a circuit comprising an inverter, the crystal of said speaker in series with said inverter, a resister in series with said crystal, said resistor being connected to ground. 3. The apparatus of claim 1, wherein said means for inputting said signal into said speaker comprises a circuit comprising a first inverter, a second inverter in series with said first inverter, the crystal of said speaker in series with said second inverter, and a capacitor in series with said crystal and said first inverter. 4. The apparatus of claim 1, wherein said means for pulsing the output sound of said speaker comprises an electronic switching circuit connected to said speaker. 5. The apparatus of claim 4, wherein said switching circuit pulses the output of said speaker between the range of 50 to 150 pulses per second. 6. The apparatus of claim 5, wherein each of said pulses comprises a period of time whereby the sound is output for approximately one-tenth thereof. 7. Apparatus for repelling pests form the body of an animal comprising a source of DC power, an ultrasonic speaker connected to said power source, and means for pulsing the high frequency sound output from said speaker between the range of 50 to 150 pulses per second. 8. A method for creating a high frequency, pulsed sound from portable apparatus comprising the steps of generating ultrasonic sound and pulsing said sound between the range of 50 to 150 pulses per second. 9. The method of claim 8, including the steps of generating said sound by a speaker and generating the signal input to said speaker by said speaker. 10. The method of claim 8, including the step of outputting said sound for approximately one-tenth of the total time of each pulse.

Inventors: BONGIOVANNI THOMAS L, BONGIOVANNI, THOMAS, L.
Applicants: BIOLOG RESEARCH INC, BIOLOGICAL RESEARCH, INC.
Application year: 1986
Main classification: H04B1
IPC codes: A01M29, B06B1