SK26498A3 - Noticeboards incorporating 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

The visual display apparatus consists of a note pad (48), the note pad (48) being a distributed acoustic radiator panel (2) with a transducer (9) mounted directly on the panel (2) to cause panel vibration to occur. as a result of its resonance.

Notebooks with built-in speakers

Technical field

The invention relates to notebooks and similar visual display devices.

BACKGROUND OF THE INVENTION

From GB-A-2262861 panel loudspeaker application, which consists of a radiating element forming a unit, it is known to design a multifunctional sandwich panel formed from two surface layers of material with a spatially core of transverse lightweight construction, arranged so that its bending strength ratio (b) ) 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 supports the panel or attaches it to the carrier loosely and without damping, and further comprises an electromechanical excitation means coupled with a panel that is used to drive more modal resonance in the radiating panel than in response to electrical input over the loudspeaker operating frequency band.

US-A-3,247,925 to WARNAKA discloses the importance of a low frequency resonant panel loudspeaker mounted on a frame and excited by an electromagnetic transducer mounted on this frame.

SUMMARY OF THE INVENTION

The present invention uses members whose species, structure and arrangement are general and / or specific from the description of related PCT application WO97 / 09842, with the same priority. 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, which members are arranged with anisotropy or without anisotropy of bending strength, with components resonant mode vibrations distributed in this region, preferably for acoustic communication with the surrounding environment and predetermined priority locations in this region for positioning the transducer, in particular for operating or moving parts thereof, which are effective with respect to acoustic vibration activities in this region and signals, usually electrical, corresponding to the acoustic content of this vibration action. The use is envisaged in the related PCT application WO97 / 09842, with the same priority, for these members as, or in passive acoustic devices without converters, such as reverberation or acoustic filtering or acoustic sounding of a room or room, such as or active acoustic devices with converters. , as in a remarkably wide range of sound sources or speakers 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 speakers.

The above elements in these devices are referred to as distributed mode acoustic radiators and have the characteristics described in the related PCT application or other characteristics described in this patent application.

The invention is made up of a visual display device consisting of a note pad or the like on which notes or the like can be stored, for example by means of integrated circuit terminals, the essence of which is a note pad or similar like board formed by a member capable of maintaining and extending the input vibration energy 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 this region for positioning the transducer. The transducer is mounted on this member at one of these locations, to cause the member to vibrate, to derive its resonance, forming an acoustic radiating panel, producing an acoustic output during resonance. The radiating panel may be provided with a lightweight core sandwiched between two cover layers. The cover layers may be paper. The core can be. formed by a paper honeycomb structure. The visual display apparatus may be provided with a support frame arranged around the periphery of the radiating panel. A resilient frame may be used to attach the radiation 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.

BRIEF DESCRIPTION OF THE DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 schematically shows an exploded loudspeaker as described and claimed in WO97 / 09842, which is related to this application in FIG. 2a is a partial sectional view of the loudspeaker along line A-A of FIG. 1, FIG. 2b is an enlarged and cross-sectional view of the loudspeaker of FIG. 2a, showing two alternative constructions.

FIG. 3 is a schematic and perspective view of a first embodiment of a note pad according to the present invention; FIG. 4 is a diagrammatic and perspective view of a second embodiment of a note pad according to the present invention; FIG. 5 is a partial sectional view of the note board of FIG. 3 and 4 and FIG. 6 shows one embodiment of a transducer.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1 shows a panel loudspeaker 81 of the type described and claimed in the international application WO97 / 09842, with the same priority, provided with a rectangular support frame 1 surrounding its inner periphery with a flexible frame 3 supporting the distributed sound radiating panel 2. Loudspeaker 81 is further provided with a transducer 9, which is described in detail in the related international applications WO97 / 09859, WO97 / 09861 and WO97 / 09858 with the same priority, and which is mounted entirely and exclusively on this or this panel 2 at a predetermined position defined by x and y coordinates the positions of which are calculated as described in related international application WO97 / 09842 with the same priority, to send bending wines to the sound radiating panel, to induce panel resonance, to produce an acoustic output.

The transducer 9 is driven by a signal amplifier 10, for example a low-frequency amplifier connected to the transducer 9 by means of conductors 28. The load and power requirement of the amplifier 10 can be quite normal, similar to conventional cone speakers, with a sensitivity of 86-88 dB / W in idle conditions. The impedance load of the amplifier is strongly resistive at 6 Ω, with a load rating of 20 to 80 W. If the core of the panel and / or the metal coverings are metal, they may act as a heat sink for heat dissipation from the converter coil and thus improve loadability.

In FIG. 2a and 2b show typical cross-sections of the loudspeaker 81 of FIG. 1. FIG. 2a, it is shown that the support frame 1 surrounding the flexible frame 3 and the panel 2 are connected to each other by respective glued joints 20. Suitable materials for the support frame are light frame structures, for example frames for extruded metal images, e.g. aluminum alloys or plastics. Suitable materials for the resilient frame are resilient materials such as foam rubber and foam plastics. Suitable adhesives for bonding joints 20 are epoxy, acrylic and cyanoacrylic adhesives, and the like.

In FIG. 2b is shown to an enlarged extent that the panel 2 is a rigid, lightweight panel consisting of a core 22, for example a rigid plastic foam 97 of cross-linked polyvinyl chloride or a lightweight structure 98, i. a honeycomb structure of metal foil, plastics or the like, with chambers extending transversely to the plane of the panel 2. The core 22 is enclosed between opposing cover layers 21, for example of paper, cardboard, plastic or metal foil or sheet. If the cover layers 21 are of plastic, they may be. fiber reinforced, for example carbon, glass, Kevlar (RTM) or the like, in a known manner, to increase their modulus.

The envisaged liner and reinforcement materials thus include carbon, glass, Kevlar (RTM), Nomex (RTM), i. aramid and similar fibers in different layers and weaves, as well as paper, laminated paper, melamine and various high modulus synthetic plastic films such as Mylar (RTM), Kaptan (RTM), polycarbonates, phenolic plastics, polyester 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 may be useful for producing very thin coating layers or coatings of smaller dimensions, up to about 30 cm in diameter, by injection molding technology. This material itself forms an oriented crystalline structure in the injection direction, which is an advantageous orientation for propagating energy with high sound frequencies from the excitation point to the panel perimeter. Injection of these and other thermoplastics further allows the positioning and alignment features such as grooves or rings to accurately position the components of the transducer, such as a coil and a magnet suspension, to be provided in the injection molding tools. In addition, some materials for weaker cores are expected to. it would be advantageous to increase the thickness of the covering layer locally, for example in the region of the annulus, up to 150% of the diameter of the converter, to strengthen this region and advantageously to double the vibration energy into the panel. In this way, the response of the high frequency is improved by the softer foam material.

The envisaged core layer materials include industrially manufactured honeycomb or corrugated structures of aluminum alloy or Kevlar (RTM), Nomex (RTM) sheet or foil or non-paint paper or paperboard and various synthetic plastic foils, as well as cellular or foam plastic or fibrous materials , even aerogel metals, as long as they have a suitable low density. Some suitable core layer materials effectively exhibit a useful self-drawing in their manufacture and / or otherwise have sufficient intrinsic strength to use without the need for lamination between layers. The high-performance lightweight core material is known under the trade name Rohacell, which is suitable as a radiant panel and which is free of covering layers. In practical terms, the aim is an overall lightweight and rigid material suitable for special purposes, in particular including the best possible contribution of the layer to the cores and cover layers and the transition between them. Some preferred panel material compositions include metal and metal alloy coating layers or alternatively carbon fiber reinforced materials. Both these materials, as well as the design with the Aerogel alloy or with the metal honeycomb core, have important RF shielding properties, which are important in some EMC (Electromagnetic Compability) applications. Conventional cone-type panels or loudspeakers do not have intrinsic electromagnetic compatibility capability in shielding. Preferred embodiments of piezoelectric or electrodynamic transducers furthermore have negligible electromagnetic radiation or stray magnetic fields. Conventional loudspeakers have a large magnetic field, up to a distance of 1 m, unless specific compensating countermeasures are taken. Where it is important to maintain shielding during use, electrical connections to the conductive portions of the relevant DML (Data Manipulation.Language) panel may be made, or electrically conductive foam or similar interfaces may be used to attach 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, further 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 bitumen-based material typically used in a loudspeaker housing, or may be of a resilient or rigid polymeric sheet material. Some materials, especially paper and board, and some cores may be self-sealing. On request, damping can be increased by the construction of the panel using flexible rather than rigid fixation adhesives.

This effective selective damping involves 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. Attaching the damping means to the edges may result in a panel whose layers are fully framed c, although its corners can often be relatively loose, for the desired widening in low frequency operation. The attachment can be by 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 attached to the layers at predetermined intermediate positions in the region in the form of suitable materials.

The described acoustic panel is two-dimensional. The sound energy from his rear face is not strongly phase related to the energy from his front face. This implies the advantage of the total sum of the sound power in the room, the distribution of sound energy at a uniform frequency, the reduced effects of reflected and still wines, together with the advantage of excellent reproduction of the natural space and environment in the reproduced sound recording.

Although radiation from the acoustic panel is very non-directional, the percentage of phase information increases off-axis. For improved focus on the artificial stereo signal, the announcer's position, and images, at the usual height of a standing person, the advantage of a slight offset for a normal seated listener contributes to optimizing the stereo effect. Also, the triangular left / right geometry creates an additional angular component relative to the listener. This provides good stereo reception.

Compared to the reproduction of a conventional loudspeaker, there is another advantage for one group of listeners. The intrinsically dispersed nature of the sound emitted by the acoustic panel gives it a sound volume that is not governed by the law of indirect dependence on the square of the distance for an equivalent point source. Since the intensity decreasing with the distance is much lower than the law of indirect dependence on the square of the distance, then, as a result, for off-center or poorly positioned listeners, 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 double problems caused by the proximity of the closer speaker, first by increasing the volume from the closer speaker first, and then by the corresponding

I lower the volume from the remote speaker.

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 FIG. 1 and 2 sa. may use in the design of the material of a normal sheet commonly used as a note or display promotional sheet, the normal processing of these sheets, for example by lamination, screen printing or spraying, without limitation.

The panel itself can be specified, dimensioned, and driven electrodynamically to operate as a flat loudspeaker of a wide coverage acoustic radiation panel. For an average number of listeners up to 10 people do so

O can use a small panel with an area of 0.56 m, or a larger panel with an area of 0.7 to 1.2 m ² for 30 to 50 people, at a natural volume level with high clear speech reproduction, as well as creating background music or relevant sound, if required. Due to the natural acoustic radiation dispersion properties of the panel, the effects of distortion 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 consumption level are required.

The acoustic panel in a preferred embodiment will consist of a core composed of a cheap paper honeycomb structure or foam having a thickness of 3 to 6 mm, on which adhesive layers of thickness of 0.08 to 0.3 mm are adhered, of reinforced paper, plastic film or paper coated with plastic foil. A preferred excitation for the inexpensive design of flat or flush-mounted converters is a piezoelectric unit operated under bending or compression loads and coupled by vibration.

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 and exciter capacitive load as well as a piezoelectric element pressure load (for a given pressure acceleration inversely proportional to frequency). properties of the board. By controlling the loss factor in the cover layers, the viscosity and elasticity of the adhesive securing the cover to the core and the piezoelectric element to the cover layer, including its coating for the illustrated image or text, and the shear and pressure volume properties of the core, the desired frequency response can be achieved.

Where higher sound levels and larger panels are coupled, good energy coverage of the panel will be provided by the alloys or partial alloys layers, with a proportionally lower loss factor, which will suitably accommodate the more powerful moving coils of the transducer. If a flat, uninterrupted surface is required on both sides of the panel, it shall be. flush mounted inverter. If magnetic shielding for these panels is required, a thin, soft steel sheet with a thickness of 0.5 mm below the surface of the coating above the transducer region may be incorporated. As a result of the improved magnetic flux, a small efficiency gain is also achieved.

Small, low-cost notebooks do not require specific framing or prescribed damping if sufficient damping of the board or counter-top is created by simply contacting the lower edge of the acoustic panel with the surface placed thereon. The device should be in the form of a photo frame with a backrest, and is effective even if it is made of light cardboard.

Some classes of rigid foam plastics, for example unplasticized PVC, have suitable bulk properties, either self-downloading or unstretched, to operate within the range of acoustic panel theory. They can be used directly as acoustic panels of this type, without additional reinforcing layers.

In FIG. 3 to 5, a note board 48 or a display advertising board or the like, with a built-in loudspeaker according to FIG. 1 and 2. Such a loudspeaker 81 comprising a fixed light distributed acoustic radiator panel 2 of the type shown in FIG. 1 and 2, the graphic information, for example text or image, of any desired type, is printed on panel 2. The graphic information may then be supplemented by an audio message through a loudspeaker to emphasize this message.

As shown in FIG. 3, a panel 48 or a display panel with a loudspeaker is mounted on a pedestal 23 in the form of a stand. Alternatively, the panel 48 or the display panel may be suspended from the wires 33 as shown in FIG. 4. Alternatively, the note pad 48 with the loudspeaker may be stored in any desired manner.

As shown in FIG. fitted with a return cuff 4 to which it is attached between its

5, the support frame 1 may be covered by the flexible frame 3, the rear face and the peripheral edge of the panel 2.

In FIG. 6 shows an inverter 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 means of an adhesive joint

20. The acoustic signal supplied to the transducer 9 by means of conductors 28 during operation causes the piezoelectric member 27 to bend, thereby causing local elastic deformation of the panel 2, for sending bending waves to the panel 2.

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PATENT

Claims (8)

A visual display device, consisting of a note pad or the like on which notes or the like can be stored, for example by means of integrated circuit terminals, characterized in that the note pad or the like (48) is formed by a maintenance-capable member (2); 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 this region for accommodating the transducer, the transducer (9) being mounted entirely and exclusively on the member at one of these vibration-inducing locations of the member to derive its resonance forming an acoustic radiating panel (2) producing an acoustic output during resonance. Visual display device according to claim 1, characterized in that the radiating panel 2 is provided with a light core (22) sandwiched between two cover layers. 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). Visual display device according to claim 4, characterized in that the support frame (1) is provided with a return cuff (4) covering the flexible frame (3). Visual display device according to claims 2 to 5, characterized in that the cover layers (21) are paper. 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 front. f * u Fig. 1 Fig. 2α Fig. 2b