TECHNICAL FIELD

The present invention relates to a device for Multiple acoustic transducer line array waveguide beam formation system and method thereof.

BACKGROUND ART

It has been seen that there are many proposals in the past regarding the subject of sound enforcement at desired location to alarm or deter intruders by applying different type of transducers and waveguides. Many types of waveguides have been proposed to achieve the purpose and line array is one such technology which is employed for the formation of directed acoustic beams at large distances and with high sound pressure levels. The line arrays are equipped with different types of waveguides along with acoustic drivers to achieve this purpose and are employed in theaters and concerts. The size of the present line arrays systems are bulky and large in size. Proposal regarding other type of ultrasonic sound reinforcement systems exists with different arrangements in which the sound is projected through high frequency ultrasonic carrier waves. The ultrasonic systems has limitations in respect of its reach and intelligent-ability of speech as the high frequency ultrasonic waves suffers distortions due to the non linear nature of the air in with the waves propagate.

US7606383  Curved line array loudspeaker  …Teaches a method of line array development  however  such type of systems are bulky in their design and are not suitable for portable/ mobile applications.
US5526456  Multiple-driver single horn loud speaker system  teaches the method of attaching the multiple speakers to a waveguide but the arrangement is not compact and has limited potential to beam the sound and produce high sound pressure levels at far-off locations.

US 4776428  Sound projection system   shows a design of a horn loaded with a speaker to project sound with high volume with wide diffusion angle  this system of single waveguide is unable to create constructive coherences for form narrow beams and is unable to project sound at long distances with compact size.

US 4344504  Directional loudspeaker  shows a combination of various loudspeakers as a line array for projecting acoustic waves   however this type of waveguide is ineffective at high frequencies and is not able to make narrow beam of sound. The system is also not compact and in order to increase high sound pressure levels with such as system it portability and mobility is questionable.

US5821470  Broadband acoustical transmitting system  teaches a method in which a parabolic dish is used to project sound directionally in narrow beam. It is applicable but with very large dish dimensions not useful for light weight and mobile applications.

US 6950530  Directional loudspeaker unit  shows the arrangement of speakers in a waveguide  however such system operates randomly at high audio frequencies   and has limitations for creating extremely high audio levels and directional acoustic beam.

US4313032  Folded horn loudspeaker system  shows a system for producing loud sound  but has a limitation of beam formation and extreme loud acoustic level formations  by the virtue of its waveguide design.

US4923031  High output loudspeaker system  shows a system for the formation of high acoustic pressure levels for speakers  however it lacks the ability to form sound beams that could reach far-off locations as the flat reflector will beam at different angles at different frequencies moreover the wave-front is spherical and not flat.

US5898138  Loudspeaker having horn loaded driver and vent  teaches an arrangement of two speakers to direct sound directionally however this system is not capable of forming tight sound beams and with high acoustic levels as the on axis response of the sound wave-front is questionable.

US6668969  Manifold for a horn loudspeaker and method …teaches a design of a system where the acoustic waves emanating from the drivers are handled in such a way that the path lengths become equal and are distributed as a line array  it is a line array and could focus sound as narrow beams but lacks method to combine multiple transducers in compact manner such that the system becomes portable and creates high sound pressure levels.

US7766122  Acoustic energy projection system. and US7837006B1  Enhanced spectrum acoustic energy projection system . These two patents are similar  with US7837006B1 showing minor changes in the central reflector and inclusion of the inner ring acoustic drivers with respect to patent US7766122 .…These patents teaches a method to generate directional beam of sound with transducers disposed in a ring however this type of design increase side-ways sound spill and is also loud for the operator as the sound wave front is not directional in itself and reflecting circular plane reduces reflection area under low frequency signals(unless the inner reflecting member’s circumference is extremely large) and if the low frequency signals are duly accommodated the performance at high frequencies results in off axis response due to the increased dimensions.

US20110019854A1 Blended waveguide and reflector…. Teaches a method to make sound wave-front on-axis at lower as well as higher frequency region with a blended waveguide (parabolic and exponential) . The design  is not capable of generating narrow beam and high output sound at far-off locations.

The problem to be addressed is by the development of a system which is mobile  light weight  modular and compact yet able to generate high sound pressure levels by employing the principles of line array in a manner such that the entire waveguide could be produced in smaller size/ dimensions. The waveguides being such that these are capable of being loaded with multiple acoustic transducers such that these are able to combine the wave-front and generate straight beams of constructively coherent sound in directional manner. It may be noted that sound pressure generated by point sources is inversely proportional to the square of the distance from the sound source and the sound pressure level generated by coherent waves are theoretically lossless but due to the nonlinearities in the air  coherent waves does exhibits a loss in inverse proportion as it travels down the distance  but is lower than the point sources. This makes the present invention deliver higher sound pressure levels directionally at desired far locations and yet being light weight for mobile applications.

OBJECTS OF THE INVENTION

It is  therefore  an object of the invention to provide a system capable of forming a tight beam of sound in a directional manner and with reduced waveguide dimension  such that multiple transducers forming a line array could be disposed in a singular waveguide in a manner that the waveguide is able combine the wave-front by superimposing plurality waveguides with a common waveguide entry and profiles capable of shaping wave-front by employing linear parabolic   tapered   and exponential profile in such a manner that the resultant wave-front is directional  on axis and the said waveguide is capable of forming a beam of sound.

It is another object of the invention to combine the plurality waveguides in a plane by combining waveguide exits in a contiguous manner  such that a waveguide matrix is formed.

It is another object of the invention to provide individual conical waveguide to plurality acoustic transducers forming a line array to provide directivity to each acoustic transducer.

It is another object of the invention to provide a common unified horn in front of the entire waveguide matrix to further focus acoustic waves emanating from plurality acoustic waveguides to provide directivity to the wave-front and control the acoustic sideway spill.

It is yet another object of the invention to provide a waveguide that has a linear parabolic member facing the acoustic transducer array and a taper with 5degree to 40degree slope disposed at the end of the array.

It is yet another object of the invention to provide a digital signal processor  to further acquire  digitize  compute  filter the acoustic signals and provide the final audio signal to the respective acoustic amplifiers.

It is yet another object of the invention to provide an audio signal from a microphone or sound player namely MP3  WAVE player etc..

It is yet another object of the invention to notify sounds and/ or intelligent verbal messages to warn or notify the intruders and with directional and high acoustic amplitude levels.

With the above and other objectives in view  as will hereinafter appear  various embodiments of the present invention are described hereunder.

SUMMARY OF THE INVENTION

According to an embodiment of the invention a device for Multiple acoustic transducer line array waveguide beam formation system comprising: a unified line array waveguide to accommodate plurality acoustic transducers arranged in a line and facing a linear parabolic surface in such a manner that it could project the acoustic beam as a unified whole and in directional and controlled manner. The waveguide also have a 5 to 40degree tapered profile at the two ends of the line array to further focus the acoustic waves; an acoustic transducer to generate acoustic wavelengths of desired frequencies; a digital signal processor to acquire audio signal and compute the output acoustic signal; an acoustic amplifier to amplify the sound to the required level; wherein the digital signal processor digitizes and computes and filter the input acoustic signal to the required output signal in accordance with the waveguide profile and provide it to the plurality of acoustic amplifiers where it is amplified to the required level and is applied their respective transducers. The various unified line array waveguide are further placed adjacent to each other such that they form a matrix constituting a line array in a flat plane  this formation creates constructive coherences between the wave fronts emanating from the plurality transducers  thereby forming acoustic waves which are projected in a controlled  directional manner and with high sound pressure level.

According to another embodiment of the invention  the unified line array waveguide focus sounds emanating from plurality transducers attached through their respective conical waveguides to further focus the sound.

According to another embodiment of the invention  the unified parabolic waveguide with plurality transducers has conical flares at the two sides of the line array followed by an exponential taper to focus and combine the wave front.

According to another embodiment of the invention  the unified parabolic waveguide is disposed in a contiguous manner forming a matrix with one sound emanating plane thereby facilitating the formation of constructively coherent wave-front in its center.

According to another embodiment of the invention  the unified parabolic waveguide when forms a matrix is further disposed with a combined waveguide having an conical and then an exponential taper to direct and control the emanating wave-front.

Brief Description of the Drawings

Figure 1 shows a detailed view of the waveguide according to the embodiment of the present invention.

Figure 2 shows the detailed view of the various components of the device according to the embodiment of the present invention.

Figure 3 shows the detailed view of the combined waveguide after it is arranged in a matrix and adjacent to each other.

For better understanding of the embodiments of the invention and to show how it may be performed  it will now be described in more detail with reference to the accompanying drawings.

Detailed Description of the Invention

The present invention can be more fully understood by reading the following detailed description of some of the embodiments  with reference made to the accompanying drawings.

As can be seen in Figure 1  it shows the shape of the unified line array waveguide 13  of the present invention in details as seen from its sides that is front 10  back 8 left 9  right 7. The section-A 2  as viewed from front 10  and the section B 3  as viewed from the back 8  are identical in profiles and are separated by a suitable distance so as to accommodate plurality acoustic transducers 6. The section-A 2  at edge-A 11  is a flat member that flares outwards and away from the axis of sound throw 1  with a slope falling in between 5degrees to 40degrees with respect to the axis of sound throw 1. Similarly the section-B 3  also forms an identical profile with symmetric slope. It has a third profile namely section C (13) which slopes away from the axis of sound throw 1  in between 5degrees to 40degrees. The unified line array waveguide 14  has a parabolic profile 4  at its left side 9  opposite to the exit of the acoustic transducers 6  such that the wave front emanating from the acoustic transducer 6  is contained on one side thereby controlling the acoustic wave spill to a larger extent. The plurality acoustic transducers 6  thus project the wave front in a unified and controlled manner along axis of throw 1  creating constructive coherence with the maxima at center.

As can be seen in Figure 2  it shows the embodiment of the present invention with required elements. The audio signal 17  is a sound input from microphone or any other audio player is applied to digital signal processor 18  which computes and analyzes the input signal and transforms it appropriately with respect to its frequency content and its amplitude to match the profiles/dimensions of the unified line array waveguide 14. It then sends the signal to the acoustic amplifiers 19  which provides suitable voltage level to the said input signal and also appropriate impedance to drive the respective plurality transducer 6.

As can be seen in Figure 3  it shows the embodiment of the present invention in such a manner that a matrix of the plurality unified line array waveguide 14  is formed. By disposing the said waveguides in contiguous manner and the matrix is so arranged that the acoustic emanating side of the said waveguides lies in one plane to facilitate the formation of constructive coherence at its centre. Thereby forming a tight beam of sound in controlled manner at its center. It also has an outer waveguide 15  with an exponential taper 20  at its sides to further contain the sound spill.