CZ58398A3 - Notepads with built-in loudspeakers - Google Patents

Abstract

Visual display apparatus comprising a notice or the like board (48), characterised in that the notice or the like board is a distributed mode acoustic radiator having a transducer (9) mounted wholly and exclusively thereon to vibrate the radiator to cause it to resonate.

Description

Patent application GB-A-2262861 discloses a panel loudspeaker design comprising a multifunctional radiating element constituting a unit sandwich panel formed from two surface layers of material with a spatial core of a transverse lightweight structure, arranged such that its flexural stiffness ratio (CB) in all directions to the square of the mass of the panel per unit surface area (μ) is at least 10, and which further comprises a fastener which carries the panel or attaches it to the carrier loosely and without damping, and further comprises an electromechanical excitation means associated with a panel that serves to drive multi-modal resonance in the radiator panel in response to an electrical input within the loudspeaker operating frequency band.

In Varnaka, IJS-A-3,247,925, the importance of a low-frequency resonant panel loudspeaker mounted on a frame and excited by an electromagnetic transducer mounted on this frame is noted.

SUMMARY OF THE INVENTION

The present invention uses members whose type, structure and arrangement are generally and / or obtainable from the description of our co-pending PCT Application No. WO97 / 09842, from the same data. Such members have the ability to maintain and propagate the input vibration energy by bending waves in the operating area or in the operating areas extending transversely to their thickness, often but not necessarily to their edges, these members being arranged with or without anisotropy of bending strength, with vibration components of the resonance vides distributed in this region, preferably for acoustically communicating with the environment and with predetermined preferential locations in the region for locating the transducer, in particular for operating or moving parts thereof, which are effective with respect to acoustic vibration activity in this region and signals , usually electrical, corresponding to the acoustic content of this vibration action. Use is envisaged in PCT Application No. V097 / 09842, from the same date, for such members as or in passive acoustic devices without converters, as reverberation or acoustic filtration or acoustic sounding of a room or room, and as or in active acoustic devices with transducers, as in a remarkably wide range of sound sources or loudspeakers when powered by input signals to convert to said sound or as microphones when exposed to sound to convert it to other signals.

In particular, the present invention relates to visual display devices with built-in acoustic devices, for example in the form of loudspeakers.

Said members are referred to as distributed radiation elements and are to be marked as in said PCT application and / or otherwise as specifically provided herein.

The invention consists of a visual display device consisting of a note pad or the like on which notes or the like can be deposited, for example by means of an integrated circuit terminal, the essence of which is that the note pad is a member capable of holding • ·

and propagating the input vibration energy by bending waves in at least one operating region extending transversely to its thickness, with resonant mode vibration components distributed at least in that region, and with predetermined preferential locations in the region for accommodating the transducer, the transducer mounted on the member at one of these locations, to cause the member to vibrate, to generate its resonance, forming an acoustic radiating panel, producing an acoustic output during resonation. The radiating panel may be provided with a lightweight core sandwiched between two cover layers. The cover layers may consist of paper. The core may be a paper honeycomb structure. The visual display apparatus may be provided with a support frame arranged around the periphery of the radiating panel. A flexible frame may be used to secure the radiator panel to the support frame. The support frame may have a back cuff covering the flexible frame. The transducer may be a piezoelectric bending member.

Overview of the drawings

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be explained in more detail with reference to the drawing, in which: FIG. 1 is a schematic representation of an exploded loudspeaker as described and claimed in our co-pending International Application No. WO97 / 09842; FIG. 2b shows the alternative embodiment of the loudspeaker of FIG. 2a, showing schematically and in perspective a first embodiment of a note pad according to the present invention; FIG. FIG. 5 is a schematic and perspective view of a second embodiment of a note pad according to the present invention; FIG. 5 is a partial cross-section of the note pad of FIGS. 3 and 4; and FIG.

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DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a panel loudspeaker 81 of the type described and claimed in our International Application No. WO97 / 09842, from the presently handled same date, which has low frequency conductors 28. The load of the normal loudspeakers is rectangular. The loudspeaker 81 is further provided with a transducer 9, which is described, for example, in our co-pending International Applications Nos. WO97 / 09859, WO97 / 09861 and WO97 / 09858, from the same date, which is mounted fully and exclusively on this or in this panel 2, at a predetermined location defined by x and y coordinates, the position of which is calculated as described in our co-pending International Application No. WO97 / 09842 from the same date , to send bending waves to the sound emitting panel, to induce resonation of the panel u, to create an acoustic output.

The transducer 9 is driven by a signal amplifier 10, for example, an amplifier connected to the transducer 9 by means of, and the power requirement of the amplifier 10 may be similar to conventional cone sensitivity types 86 to 88 dB / V at ambient load. The amplifier load impedance is strongly resistive at 6 ohms, at 20 to 80V. When the core of the panel and / or the metal layers are metal, they can act as a heat sink to dissipate heat from the inverter coil and thus improve load capacity.

Figures 2a and 2b show typical cross-sections of the loudspeaker 81 of Figure 1. Fig. 2a shows that the support frame 1 surrounding the flexible frame 3 and the panel 2 are joined together by respective glued joints 20. Suitable materials for the support frame are lightweight frame structures, for example, frames for pictures of extruded metal, for example aluminum · »· .4444 ·· 4444 44 44 · 4 4444

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444 4 4 · 4444 4 »44444 444» 44 444 44 44 4 4 44 Alloys or plastics. Suitable materials for the flexible frame are resilient materials such as foam rubber and foam plastics. Suitable adhesives for glued joints 20 are epoxy, acrylic and cyanoacrylic adhesives, etc.

In Fig. 2b it is shown on an enlarged scale that the panel 2 is rigid, the light panel consisting of a core 22, for example a rigid plastic foam 97 of cross-linked polyvinyl chloride or a lightweight structure 98, ie a honeycomb structure of metal foil, plastics or the like. with chambers extending transversely to the plane of the panel 2, the core 22 being enclosed between opposing cover layers 21, for example of paper, cardboard, plastic or metal foil or sheet. When the cover layers 21 are plastic, they can be reinforced with fibers, for example carbon, glass, Kevlar CRTM) or the like in a manner known per se, to increase their modulus.

The envisaged materials for the cover layers and reinforcement thus include carbon, glass, Kevlar CRTM), Nomex CRTM), ie aramid and the like fibers in different layers and weaves, as well as paper, laminated paper, melamine and various synthetic plastic films and high modulus, such as Mylar CRTM), Kaptan CRTM), polycarbonates, phenolic plastics, polyesters or related plastics and fiber reinforced plastics, etc., and metal foils or sheets. Research on the Vectra grade of liquid crystal polymer thermoplastics shows that they can be useful for producing ultra-thin coatings or coatings of smaller sizes, up to about 30 cm in diameter, by injection molding technology. This material itself creates an oriented crystalline structure in the injection direction, which is an advantageous orientation for propagating high-frequency energy from the excitation point to the panel perimeter. Further, the injection of these and other thermoplastics allows the positioning features to be arranged in the injection molding tools.

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a honeycomb of aluminum alloy, uncoated paper or, in particular, and alignment, such as grooves or rings for precisely trimming the components of the transducer, such as a coil and a magnet suspension. In some materials for weaker cores, it would further be advantageous to locally increase the thickness of the cover, for example in the region of the annulus, up to 150¾ of the diameter to amplify this region and advantageously double. In this way, a softer foam material improves the high frequency response. Intended core layer materials include industrially manufactured or corrugated structures of Kevlar (TM) sheets or foils, Nomex (RTM), cardboard and various synthetic plastic sheets, as well as expanded or foamed plastics or fibrous materials, even aerogel metals, provided they have a suitable low density . Some suitable core layer materials effectively exhibit useful self-contracting in their manufacture and / or otherwise have sufficient intrinsic rigidity for use without the need for lamination between layers. The high performance lightweight core material is known under the trade name "Rohacel1", which may be suitable as a radiating panel, and which is free of covering layers. Practically speaking, the purpose is a light and rigid material comprising the best possible fit for special purposes, the benefit of the layer for the cores Some of the preferred and covering layers and the transition between them. the material compositions for the panel include both carbon and metal coating layers of metal and metal alloys. Aerogel alloy or alternatively reinforced materials Both these materials and the construction with or with a honeycomb core have important RF shielding properties that should be of importance in some EMC applications (electromagnetic compatibility). Conventional cone-type panels or speakers do not have their own electromagnetic compatibility when shielding. Conveniently

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In addition, the 4 piezoelectric or electrodynamic transducer embodiments have negligible electromagnetic radiation or stray magnetic field. Conventional loudspeakers have a large magnetic field, up to 1 m, unless specific compensating countermeasures are taken. Where it is important to maintain shielding during use, electrical connection of the conductive parts of the relevant DML (Data Manipulation Language) panel may be made, or an electrically conductive foam or similar interface may be used to connect the edges of the panel. The resilient frame 3 can damp the edges of the panel 2 to prevent excessive movement of these edges. Further or alternatively, additional damping may be used, for example by means of damping pads glued to the panel at selected locations, to damp excessive movements of the panel to ensure a uniform distribution of resonance across the panel. The pads may be of a bitumen-based material typically used in a loudspeaker housing, or may be a flexible or rigid polymeric sheet material. Some materials, especially paper and board, and some cores may be self-damping. On request, damping can be increased by the construction of the panel by the use of flexible rather than rigid fixation adhesives.

This effective selective damping comprises specifically attaching the damping means to the panel, including its layers, which permanently bond to it. The edges and corners may be particularly important for the predominant and less dispersed types of panel vibration at low frequency. By attaching the damping means to the edges, a panel can be formed whose layers are fully framed, although its corners can often be relatively loose, it can be said for the desired expansion in low frequency operation. The connection can be made with adhesive or self-adhesive materials. Other types of useful damping means, in particular with respect to finer effects and / or mid and high frequencies, may be in the form of suitable

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The materials described above are attached to the layers at predetermined intermediate positions in the region described. The acoustic panel described is two-dimensional. The sound energy from his rear cell is not strongly phased with the energy from his front forehead. This results in the benefit of the total sum of the acoustic power in the room, the distribution of sound energy at a uniform frequency, the reduced effects of reflected and standing waves, together with the advantage of excellent reproduction of the natural space and environment of the reproduced sound recording.

Although non-ventilated, the percentage from the acoustic panel is very off-axis ratio. For enhanced focus on artificial stereo, on the position of the announcer, and on images, at the usual height of a standing person, the advantage of a slight offset for a normally seated listener contributes to optimizing the stereo effect. Also, the triangular left / right geometry creates an additional angular component relative to the listener. Thus good stereo reception is achievable.

Compared to the reproduction of a conventional loudspeaker, there is another advantage for one group of listeners. The intrinsically dispersed nature of the acoustic panel's sound emission gives it a sound volume that is not governed by the law of indirect dependence on the square of distance for the equivalent point intensity of decreasing distance is much given by the law of indirect dependence on the square of distance, then the magnetic field strength of the panel speaker increases the stereo effect compared to conventional speakers. This is because the off-center listener does not suffer from the double problem caused by the proximity of the proximal speaker, first by increasing the volume from the proximal speaker excessively, and then reducing the source accordingly. Because lower than the volume from the far speaker.

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Another advantage of the flat light panel speaker is that it is visually attractive, has good sound quality and requires only a transducer and not a speaker crossover for the full range of sound from each panel membrane.

The method of manufacturing the acoustic panel of FIGS. 1 and 2 can be used in the design of the material of a conventional board commonly used as a note or display propagation board, the normal processing of such boards, for example laminating, screen printing or spraying without limitation.

The panel itself may be specified, dimensioned, and excited electrodynamically to operate as a flat loudspeaker of a wide coverage acoustic radiator panel. For an average audience of up to 10 people, a small panel of 0.56 square meters or a larger panel of 0.7 to 1.2 square meters can be used for 30-50 people, at a natural volume level with highly distinct speech reproduction, as well as creating background music or relevant audio if desired. Due to the natural acoustic radiation diffusion panel properties, distortion effects of local edge reflections are minimized.

Real physical barriers due to the dimensions of the acoustic panel will not significantly impair sound propagation.

For a given level of clarity and clarity, a lower sound level and a lower power level are required.

The acoustic panel in the preferred embodiment will consist of a core composed of a cheap paper honeycomb structure or a foam of 3 to 6 mm thickness on which are adhered the covering layers of 0.08 to 0.3 mm thickness, of reinforced paper, plastic foil or paper coated with plastic foil. A preferred excitation for a low-cost design of flat or flush-mounted converters is a piezoelectric unit operating under bending or compression loads and coupled • 4 4444 ·· 4444

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44 vibrations.

These transducers have a naturally increasing acoustic output, with a frequency that is presumably optimally set to a flat frequency response by combining a series of resistive excitation on the exciter capacitance load and also the pressure load of the piezoelectric element (for given pressure acceleration inversely proportional to frequency). sheet. By controlling the loss factor in the cover layers, the viscosity and the elasticity of the adhesive securing the cover to the core, the piezoelectric element to the cover layer, including its coating for the illustrated image or text, and the shear and pressure volumetric properties of the core can achieve the desired frequency response.

Where higher sound levels and larger panels are coupled, good energy coverage of the panel will be provided by alloy or partial alloy layers, with a proportionally lower loss factor that appropriately adapts to the more powerful moving coils of the drive. When flat, uninterrupted on both sides of the panel is required, the drive must be flush into the panel. If magnetic shielding is required for these panel panel surfaces, a thin, soft steel sheet thickness may be incorporated below the coating surface above the drive area. As a result of the improved magnetic flux, a small efficiency gain is also achieved.

Small, cost-effective note pads do not require specific framing or prescribed damping when sufficient damping of the board or opposite upper shape is made by simply contacting the lower edge of the acoustic panel with the surface on it. The device should be in the shape of a photo frame with a back support. effective even when made of light cardboard.

Some classes of rigid foam plastics, for example

0.5 mm non-plasticized F'VC have suitable bulk properties, either

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000 0 0 0 imaging built-in loudspeakers are self-downloading or not downloaded, to operate within the acoustic panel theory range. They can be used directly as acoustic panels of this type, without additional reinforcing layers.

3 to 5, there is shown a note pad 48 or a propagation board or the like, with a loudspeaker according to FIG. 1a. Such a 81 comprising a rigid, lightweight unfolded acoustic radiating panel 2 of the type shown in FIGS. for example, text or image, of any desired type, printed on panel 2. The graphic information may then be supplemented by an audio message through the loudspeaker to emphasize the message.

As shown in FIG. 3, the loudspeaker panel 48 or display panel is mounted on a pedestal 23 in the form of a stand. Alternatively, the panel 48 or the display panel may be suspended on the wires 33 as shown in FIG. Alternatively, the loudspeaker note pad 48 may be stored in any desired manner.

As shown in Fig. 5, the support frame 11 may be provided with a back collar 4 to cover the flexible frame 3, which is attached between its rear face and the peripheral edge of the panel 2.

6 shows an inverter 9 for an exploded panel 2 in the form of a crystalline bending piezoelectric member 27 attached to a disc 118, for example of brass, which is attached to the face of the panel 2, for example by gluing 20. by means of the conductors 28 by means of the conductors 28 cause the piezoelectric member 27 to bend, thereby causing local elastic deformation of the panel 2, for sending bending waves to the panel 2.

Claims (8)

000 0 A visual display device, comprising a note or similar board (48) on which notes or the like can be stored, for example by means of integrated circuit terminals, characterized in that the note or similar board (48) is formed by a member (2) comprising: Capable of maintaining and propagating the input vibration energy by bending waves in at least one operating region extending transversely to its thickness, with resonant mode vibration components distributed at least in this region, and with predetermined preferential locations in the region for positioning the transducer, wherein the transducer (9) is mounted fully and exclusively on the member at one of these vibration inducing locations for the member to generate its resonance, forming an acoustic radiating panel (2), producing an acoustic output during resonation. Visual display device according to claim 1, characterized in that the radiating panel (2) is provided with a lightweight core (22) sandwiched between two cover layers (21). Visual display device according to claim 2, characterized in that it is provided with a support frame (1) arranged around the periphery of the radiating panel (2). Visual display device according to claim 3, characterized in that it is provided with a flexible frame (3) attaching the radiating panel (2) to the support frame (1). • · 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Visual display device according to claim 4, characterized in that the support frame (1) is provided with a return collar (4) covering the flexible frame (3). A visual display device according to claims 2 to 5, characterized in that the cover layers (21) are formed by paper mills. Visual display device according to claims 2 to 6, characterized in that the core (22) is formed by a paper honeycomb structure. Visual display device according to claims 2 to 6, characterized in that the transducer (9) is formed by a piezoelectric bending member.