JPH11514509A - Loudspeaker composed of panel-shaped acoustic radiating elements - Google Patents

Abstract

(57) [Summary] The tile is in the form of a distributed mode acoustic radiator (2), which is entirely attached to the radiator only, and causes the radiator to vibrate to cause resonance. A ceiling tile (36) for a suspended ceiling incorporating a loudspeaker (81) featuring a transducer (9).

Description

Description: TECHNICAL FIELD The present invention relates to a loudspeaker comprising a panel-shaped acoustic radiating element . More particularly, the invention relates to a loudspeaker comprising a panel-shaped acoustic radiating element. 2. Description of the Related Art It is formed of two skins and a spacing core having a lateral cell structure, and a ratio of bending stiffness (B) in all directions to a cube of panel mass per unit surface area (μ) is at least 10. A resonant multi-mode radiating element, which is an integral sandwich panel; mounting means for supporting the panel in a free, non-attenuating state, or attaching a supporting body to the panel; and electricity within a working frequency band of the loudspeaker. An electromechanical drive coupled to the panel adapted to excite a multi-mode resonance in the radiant panel in response to an input, wherein a panel loudspeaker comprising: It can be seen from British Patent Publication No. 2262861. It has a wide range of uses for speaker-based audio distribution in standard modular form, interchangeable with commercially available ceiling tiles in the format of about 600 x 600 mm, with clear speech and music for large areas. Is an even distribution. Certain conventional moving coil drivers and panel variants are currently being made for this application. Existing technology uses cone-type moving coil speakers that are compatible with the frame and acoustic baffle. Although commonly used for modest cost and ease of use, they are severely hotspots (excessive sound intensity) and directionally affected, thereby causing off-axis clarity It will deteriorate. More equipment is required to provide uniform coverage over a larger area. Another known development uses a cone-type speaker, where the cone is a polystyrene structure with a flat front surface such that it can be painted. When combined with an additional moving coil driver that matches the diaphragm, the latter configured to acoustically contract at higher frequencies can provide a wider radiation pattern when compared to conventional cone speakers. These polystyrene foam speaker units require a chassis and an acoustic panel to attach them in place. DISCLOSURE OF THE INVENTION In embodiments of the present invention, the applicant generally or specifically executes PCT application number (the applicant's case number P5711) filed on the same date as the present application by executing the teaching of the applicant. Utilize components of achievable properties, structures and shapes. The member retains and propagates the input vibrational energy by bending waves transversely to its thickness, often in the working area, but not necessarily to the edge of the member, but not necessarily to the edge. Configured to effectively distribute a resonant mode vibration component over the working area for acoustic coupling with ambient air with or without anisotropy of flexural stiffness. The transducer means, in particular the active and movable parts of the transducer, which are effective with respect to the acoustic vibratory movement in said area and the signals which generally correspond electrically to the acoustic content of such vibratory movement. A predetermined priority position or location within said area. The user may be required to provide a "passive" sound device or a member in a "passive" sound device without tone transducer means for reverberation, acoustic filtering or acoustically "speaking" in a space or open space, and sound. "Active" with transducer means, such as a loudspeaker, or a microphone for receiving the sound to be converted to another signal, when the input signal to be converted to is supplied. A description of components as acoustic devices or components in "active" acoustic devices can be found in the International Application Number filed by the Applicant, filed on the same date as the filing date (Applicant File No. P.5711). it can. The invention relates in particular to an active acoustic device in the form of a loudspeaker intended for use in suspended ceiling tiles. The components described above are referred to as distributed mode radiators, and are characterized as those described in detail in the PCT application or herein. The present invention is a ceiling tile incorporating a loudspeaker for a suspended ceiling, wherein the tile is in the form of a distributed mode acoustic radiator, which is entirely attached to the radiator only, causing the radiator to vibrate and cause resonance The transducer is characterized by: An elastic suspension is arranged on the periphery of the radiator, and the radiator is supported in the suspended ceiling. The radiator may be a rigid lightweight panel made of a cell core sandwiched between highly rigid skins. BRIEF DESCRIPTION OF THE DRAWINGS The present invention is schematically illustrated by way of example in the accompanying drawings. FIG. 1 is a schematic diagram illustrating a distributed mode loudspeaker described and claimed in International Application No. (Applicant Case Number P5711) by the Applicant. FIG. 2a is a partial cross-sectional view along the line AA of FIG. FIG. 2b is an enlarged cross-sectional view of a distributed mode radiator of the type shown in FIG. 2a, but showing two alternative configurations. FIG. 3a is a perspective view of a room incorporating a suspended ceiling. FIG. 3b is a cross-sectional view of one embodiment of a distributed mode loudspeaker in the form of a ceiling tile according to the present invention. BEST MODE FOR CARRYING OUT THE INVENTION Referring to FIG. 1 of the drawings, the type described and claimed in an international application number filed by the present applicant filed on the same date as the present application (the applicant's case number P.5711). A panel-shaped loudspeaker (81) is shown. The loudspeaker (81) comprises a rectangular frame (1) supporting an elastic suspension (3) supporting a distributed mode sound radiator panel (2) around an inner peripheral portion. For example, as described in detail with reference to an international application number filed by the present applicant filed on the same date as the present application (the applicant's case number P.5683 / 4/5), the transducer (9) has a dimension x And at a predetermined location determined by y, the whole is mounted only on panel (2) or only in panel (2), the location of the transducer location shall be filed on the same day as the present application. Calculated as described in the applicant's international application number (Applicant case number P.5711), sends a bending wave into the panel, resonates the panel and emits acoustic output. I have. The transducer (9) is driven by a signal amplifier (10), such as an audio amplifier, connected to the transducer by a conductor (28). Amplifier loading and power requirements are quite common, similar to conventional cone loudspeakers with sensitivities on the order of 86-88 dB / watt at room loading. The load impedance of the amplifier has a large resistance of 6 ohms and the power handled is 20-80 watts. If the panel core or skin is made of metal, it may be formed to act as a heat sink for the transducer to extract heat from the motor coil of the transducer and improve power consumption. 2a and 2b are partial typical cross-sectional views of the land speaker (81) of FIG. FIG. 2a shows that the frame (1), the suspension (3) and the panel (2) are connected together by joints (20), each connected by an adhesive. Suitable materials for the frame include lightweight frames, for example, painting frames made of aluminum alloy or plastic, for example extruded metal. Suitable surrounding materials include elastic materials such as foam rubber and foam plastic. Suitable adhesives for joint (20) include adhesives such as epoxy, acrylic, and cyano-acrylate. FIG.2b shows that the panel (2) is a rigid plastic foam (97), for example a crosslinked polyvinyl chloride, or a cellular matrix (98), i.e. the cells extend transversely to the plane of the panel. E.g., a rigid, lightweight panel having a core (22) of a honeycomb matrix of metal foil, plastic, etc., surrounded by opposed skins (21) of paper, card, plastic or metal foil or sheet, for example. This is shown in an enlarged manner. When the skin is made of plastic, it is sufficient that the skin is reinforced by known means, for example, with a fiber made of carbon, glass, Kevlar (registered trademark) or the like so as to increase the rigidity of the skin. Anticipated skin layer materials and reinforcements include carbon, glass, Kevlar®, Nomex®, fibers such as aramid of various skins and fabrics, and paper, bonded paper laminates, melamine and mylar ( (Registered Trademarks), various rigid plastic films and metal sheets or foils such as Captan (R), polycarbonate, phenolics, polyesters or related plastics, and fiber reinforced plastics and the like. Studies on the Vectra grade of liquid crystal polymer thermoplastics show that this thermoplastic is effective for injection molding ultra-thin skins or smaller sized shells up to about 30 cm in diameter . The material itself forms a crystal structure that is oriented in the direction of emission, i.e., the preferred direction for good propagation of high sound energy from the driving point to the perimeter of the panel. This, and further molding on another thermoplastic, allows the molding die to be positioned and aligned, e.g., grooves or rings for accurate positioning of transducer parts such as motor coils and magnet suspension. Can bring features. In addition, for some of the more brittle core materials, for example, in the region up to 150% of the transducer diameter, ie, in the annulus, the skin thickness is locally enhanced to strengthen that region and effectively couple vibrational energy to the panel. It would be beneficial to increase this. The high frequency response is improved by this means with a more flexible foam material. Possible core skin materials are aluminum alloy sheets or foils formed into honeycombs or corrugations, or Kevlar®, Nomex®, plain or glued paper and various synthetic plastic films, Foamed or foamed plastics, or pulp materials, also include airgel metals, if suitably of low density. Some suitable core skin materials exhibit sufficient self-skin formation available in their manufacture or have sufficient inherent stiffness to be used without overlying skin layers. High performance cell core materials are suitable as radiating panels, and the skinless trademark "Rohacell" is known. In practice, the objectives relate specifically to the overall lightness and stiffness adapted to the particular purpose, including optimizing the contribution from the core and skin layers and the transition between them. Some preferred formulations for panels use metal and metal alloy skins, or carbon fiber reinforcement. Both of these, and designs with alloy airgel or metal honeycomb cores, also have substantial radio frequency screen properties that are important in some electromagnetic (EMC) applications. Conventional panel or core type speakers do not have intrinsic electromagnetic screen capabilities. In addition, preferred forms of piezoelectric and electrokinetic transducers have negligible electromagnetic radiation or stray magnetic fields. Conventional loudspeakers have large magnetic fields at distances up to one meter until specific compensation measures are taken. In one application, where it is important to maintain screening, electrical connections may be made to the conductive portion of an appropriate DML panel or to an electrically conductive foam, or a similar interface may be used. May be used to attach edges. The suspension (3) only needs to dampen the edge of the panel (2) so that the edge of the panel does not move excessively. Further, additional damping may be provided, for example as a patch coupled to the panel at a selected location to dampen excessive motion and distribute the resonance evenly on the panel. The patch may be composed of a bitumen-based material as commonly used in conventional loudspeaker enclosures, or may be composed of an elastic or rigid polymer sheet material. Certain materials, ie, good papers and cards, and certain cores may self dampen. If desired, the vibration damping in the panel structure may be enhanced by using an elastic fixing adhesive instead of a hard fixing adhesive. Effective selective damping involves the unique application of a permanently incorporated means to a panel containing sheet material. Edges and corners are particularly important for the low variance low frequency vibration modes of the panel of the present invention. Although the corners are often relatively free with respect to the desired extension to lower frequency operation, the edge-wise anchoring of the damping means is effective for panels where the sheet material is fully formed in the frame. Can be helpful. The attachment can be made with an adhesive or a self-adhesive material. Another form of effective damping, particularly for smaller effects or intermediate and higher frequencies, is by means of a suitable mass fixed to the sheet material at a location located at a predetermined effective middle of said area. . The acoustic panel described above is bidirectional. The sound energy from the back is not in any phase related to the sound energy from the front. Therefore, the advantages of overall sound output in a room, sound energy with a uniform frequency distribution, reduced reverberation and standing wave effects, as well as the benefits of excellent reproduction of natural space and surroundings in reproduced audio recordings. Have. Radiation from acoustic panels is generally non-directional, with the proportion of information-related phase increasing off-axis. For an improved focus on the virtual stereo image, placing a pictorial speaker at the height of a normal person standing up would benefit from a moderately off-axis placement for a normally seated audience. And optimize the stereo effect. Similarly, the left / right geometry of the triangle with respect to the audience forms another angular component. Therefore, a good stereo can be obtained. There are additional advantages for grouped audiences as compared to conventional speaker playback. The inherent distribution characteristics of the acoustic panel sound emission provide a volume that is not subject to the inverse square law for equal point source distances. Since the decrease in intensity with distance cannot be predicted at all by the inverse square law, the intensity of the panel speaker is superior to conventional speakers for the audience who is off-center and is in an insufficient position. Will promote. This is primarily due to the fact that the audience at the off-center location is too close to the closer speaker, which firstly increases the loudness of the sound from the closer speaker. This is because the two problems of reducing the volume of the sound from another loudspeaker are not encountered. Good sound quality, requires only one transducer, visually striking, flat, lightweight panel-like design that does not cross over to the full range of sound from the diaphragm of each panel There are also advantages of speakers. FIG. 3 shows a ceiling tile (36) of the type adapted to be supported on a grid-like hanging frame (99) so as to form a suspended ceiling, ie a core (22) with a skin (2 1) on both sides. FIG. 3 shows a ceiling tile (36) formed as a loudspeaker (81) of the kind shown in FIGS. 1 and 2 consisting of a rigid lightweight multimode resonant panel (2) surrounded by. The panel (2) is attached at its periphery to an elastic suspension (3) made of foam rubber supported on a frame (99). The suspension (3) is attached to either the panel (2) or the frame (99) by an adhesive, but the connection may simply be by gravity. The panel (2) supports, for example, a transducer (9) of the type shown in FIGS. 7 to 12, and sends bending waves to the panel, causing the panel to resonate and emit acoustic output. The transducer (9) may be arranged on a panel as described in International Application No. (file number P5711 of the present applicant) by the present applicant. In a preferred example of good quality, the acoustic panel is manufactured as a foamed polystyrene foam core, typically having a density of 100 g / m3 and a thickness of 8 mm, and is skinned with a 0.1 mm hardened aluminum alloy skin. A soft foam or felt strip approximately 3mm thick is fixed to the rim and, when placed on the ceiling frame, partially follows the installation, helping to reduce the possibility of vibrations in the ceiling frame section Also. A preferred form of excitation is a 25 mm or 38 mm voice coil, an integral moving coil inertial transducer with 6 ohm impedance and 40 watts of processing power, with the coil directly coupled to the panel surface. I have. A compact enclosing and self-sealing cup-shaped magnet system may be directly coupled to the panel via an elastic isolation ring selected for vibratory mechanical properties and dimensional stability. Depending on the application, a low-cost foam ceiling tile may have a flame-retardant lightweight alloy foil layer that can be formed of a plastic foam cored paperboard material and driven by low-cost piezoelectric vibration excitation. A reduced maximum sound level is obtained that is more sufficient for the distribution of personal announcements, voiceovers and background music. Wide area coverage is maintained. When a metal or carbon conductive skin or core is used, the speakers need only be ground bonded or grounded to maintain the EMC screen of the installed structure. Industrial Applicability The suspended ceiling tile loudspeaker according to the present invention does not require a frame, chassis or acoustic baffle. All the speaker panels need to be integrated and arranged at positions such as immovable decorative ceiling tiles. Acoustic panels are relatively lightweight, reducing ceiling loading and mounting hassle. It is easy to manufacture fire resistant. With no noticeable acoustic effect, it is possible to decorate, paint or paper so that the acoustic panel is not visible during the installation of the suspended ceiling. It does not cause any undesired damage to the performance as compared to the very brittle cone type speaker diaphragm. It is also important that the sound distribution obtained by the acoustic panel loudspeaker has great advantages. The combination of high brightness and wide angle coverage can achieve excellent acoustic performance in typical large area installations, with almost half the number of loudspeakers conventionally installed, and save considerable installation costs. Will be.

[Procedural Amendment] Patent Act Article 184-8, Paragraph 1 [Date of Submission] Nov. 10, 1997 [Amendment] In another known development, the cone is flat so that it can be painted. A cone type speaker having a polystyrene structure with a suitable front surface is used. When combined with an additional moving coil driver that matches the diaphragm, the latter configured to acoustically contract at higher frequencies can provide a wider radiation pattern when compared to conventional cone speakers. These polystyrene foam speaker units require a chassis and an acoustic panel to attach them in place. U.S. Pat. No. 4,506,117 to Multiphone discloses a suspended ceiling panel provided with an electro-acoustic transducer manufactured solid with a metal base plate. DISCLOSURE OF THE INVENTION In embodiments of the present invention, by carrying out the teachings of the present applicant in PCT Publication No. Utilize structural and shaped members. The member maintains and propagates the input vibrational energy by bending waves transversely to its thickness, often in the working area, but not necessarily to the edge of the member, but not necessarily to the edge. With the capability and with or without anisotropy of flexural rigidity, it is configured to effectively distribute a resonance mode vibration component on the working area for acoustic coupling with ambient air. The transducer means, in particular the active and movable parts of the transducer, which are effective with respect to the acoustic vibratory movement in said area and the signals which generally correspond electrically to the acoustic content of such vibratory movement. A predetermined priority position or location within said area. The user may have a component as a "passive" acoustic device or a component in a "passive" acoustic device without tone transducer means, with respect to reverberation, acoustic filtering or acoustically "speaking" in space or open space, and sound. "Active" with transducer means, such as a loudspeaker, or a microphone for receiving the sound to be converted to another signal, when the input signal to be converted to is supplied. A description of components as acoustic devices or components in "active" acoustic devices can be found in International Publication No. WO 97/09842 filed on the same date as the present application. The invention relates in particular to an active acoustic device in the form of a loudspeaker intended for use in suspended ceiling tiles. The components described above are referred to as distributed mode radiators, and are characterized as those described in detail in the PCT application or herein. The present invention is a ceiling tile incorporating a loudspeaker for a suspended ceiling, the tile having the ability to maintain and propagate input vibrational energy by bending waves in at least one laterally extending working area of thickness. A resonant mode vibration component is distributed over at least one of the regions and comprises a member adapted to have a predetermined preferential location, or position, in the region for the transducer means, wherein the member has a predetermined location or position. One of the components is entirely attached to the member only, and includes a transducer adapted to vibrate the member to cause resonance to form an acoustic radiator, and to provide an acoustic output upon resonance. The suspended ceiling tile may be characterized by being composed of, for example, a foam plastic cell core sandwiched by a highly rigid skin. The elastic suspension may be arranged on the periphery of the radiator and support the radiator on the suspended ceiling frame. The transducer may be any inertial vibration transducer. BRIEF DESCRIPTION OF THE DRAWINGS The present invention is schematically illustrated by way of example in the accompanying drawings. FIG. 1 is a schematic diagram illustrating a distributed mode loudspeaker as described and claimed in International Publication No. WO 97/09842 by the applicant. FIG. 2a is a partial cross-sectional view along the line AA of FIG. FIG. 2b is an enlarged cross-sectional view of a distributed mode radiator of the type shown in FIG. 2a, but showing two alternative configurations. FIG. 3a is a perspective view of a room incorporating a suspended ceiling. FIG. 3b is a cross-sectional view of one embodiment of a distributed mode loudspeaker in the form of a ceiling tile according to the present invention. BEST MODE FOR CARRYING OUT THE INVENTION Referring to FIG. 1 of the drawings, the type described and claimed in an international application number filed by the present applicant filed on the same date as the present application (the applicant's case number P.5711). A panel-shaped loudspeaker (81) is shown. The loudspeaker (81) comprises a rectangular frame (1) supporting an elastic suspension (3) supporting a distributed mode sound radiator panel (2) around an inner peripheral portion. For example, as described in detail with reference to an international application number filed by the present applicant filed on the same date as the present application (the applicant's case number P.5683 / 4/5), the transducer (9) has a dimension x Elastic suspension (3) consisting of foam rubber supported on a frame (99), either entirely on the panel (2) or at the periphery at a predetermined location determined by y and Mounted on top. The suspension (3) is attached to either the panel (2) or the frame (99) by an adhesive, but the connection may simply be by gravity. The panel (2) supports, for example, a transducer (9) of the type shown in FIGS. 7 to 12, and sends bending waves to the panel, causing the panel to resonate and emit acoustic output. The transducer (9) need only be arranged on a panel as described in WO 97/09842 by the applicant. In a preferred example of good quality, the acoustic panel is manufactured as a foamed polystyrene foam core, typically having a density of 100 g / m3 and a thickness of 8 mm, and is skinned with a 0.1 mm hardened aluminum alloy skin. A soft foam or felt strip approximately 3mm thick is fixed to the rim and, when placed on the ceiling frame, partially follows the installation, helping to reduce the possibility of vibrations in the ceiling frame section Also. A preferred form of excitation is a 25 mm or 38 mm voice coil, an integral moving coil inertial transducer with 6 ohm impedance and 40 watts of processing power, with the coil directly coupled to the panel surface. I have. A compact enclosing and self-sealing cup-shaped magnet system may be directly coupled to the panel via an elastic isolation ring selected for vibratory mechanical properties and dimensional stability. Depending on the application, low-cost foam ceiling tiles may have a flame-retardant lightweight alloy foil layer that can be formed of a plastic foam cored paperboard material and driven by low-cost piezoelectric vibration excitation. A reduced maximum sound level is obtained that is more sufficient for the distribution of personal announcements, voiceovers and background music. Wide area coverage is maintained. When a metal or carbon conductive skin or core is used, the speakers need only be ground bonded or grounded to maintain the EMC screen of the installed structure. Industrial Applicability Claims A suspended ceiling tile (36) incorporating a loudspeaker (81), said tile having the ability to maintain and propagate input vibrational energy by bending waves in at least one laterally extending working area of thickness. A member (2) adapted to distribute a resonance mode vibration component over at least said one region and to have a predetermined preferential location, i.e. a position, in said region for the transducer means, said member (2) A transducer entirely attached to said member at one of said locations or positions, said member being vibrated to cause resonance to form an acoustic radiator, and to provide an acoustic output when resonated. A suspended ceiling tile (36) having (9). 2. The suspended ceiling tile according to claim 1, wherein the member (2) is made of a cell core (22) sandwiched by a highly rigid skin (21). 3. 3. An elastic suspension (3) arranged at the periphery of the radiator (2) and adapted to support the radiator in a suspended ceiling frame (99). Suspended ceiling tile as described. 4. 4. Suspended ceiling tile according to claim 2 or 3, as dependent on claim 2, wherein said cell core (22) is formed from foam plastic (97). 5. A suspended ceiling tile according to any of the preceding claims, wherein the transducer (9) is an inertial vibration transducer.

────────────────────────────────────────────────── ─── Continuation of front page    (31) Priority claim number 9606836.6 (32) Priority date March 30, 1996 (33) Priority claim country United Kingdom (GB) (81) Designated countries EP (AT, BE, CH, DE, DK, ES, FI, FR, GB, GR, IE, IT, L U, MC, NL, PT, SE), OA (BF, BJ, CF) , CG, CI, CM, GA, GN, ML, MR, NE, SN, TD, TG), AP (KE, LS, MW, SD, S Z, UG), UA (AM, AZ, BY, KG, KZ, MD , RU, TJ, TM), AL, AM, AT, AU, AZ , BB, BG, BR, BY, CA, CH, CN, CU, CZ, DE, DK, EE, ES, FI, GB, GE, H U, IL, IS, JP, KE, KG, KP, KR, KZ , LC, LK, LR, LS, LT, LU, LV, MD, MG, MK, MN, MW, MX, NO, NZ, PL, P T, RO, RU, SD, SE, SG, SI, SK, TJ , TM, TR, TT, UA, UG, US, UZ, VN (72) Inventor Harris Neil             UK Cambridge CB2 5             Jeff Great Shelford             Divie Crescent 9

Claims (1)

[Claims] 1. The tiles are composed of distributed mode acoustic radiators and are entirely attached to the radiators only And a transducer that vibrates the radiator to cause resonance. A suspended ceiling tile that incorporates udo speakers. 2. The radiator is arranged on the periphery of the radiator, and supports the radiator on a suspended ceiling. The suspended ceiling tile according to claim 1, characterized in that the suspended ceiling tile is elastic. 3. The radiator is composed of a rigid cell core sandwiched by a highly rigid skin. 3. The hanging ceiling according to claim 1, wherein the hanging ceiling is a lightweight panel. Well tile. 4. The cell core is formed of foam plastic. Item 4. The suspended ceiling tile according to item 3. 5. The transducer is an inertial vibration transducer. The suspended ceiling tile according to any one of claims 1 to 4.