CZ58598A3 - Projection screen with built-in loudspeakers - Google Patents

Abstract

A display screen (32), e.g. a projection screen comprising a panel having a light reflective surface, characterised in that the screen is a distributed mode acoustic radiator loudspeaker having a transducer (9) mounted wholly and exclusively thereon to vibrate the radiator to cause it to resonate to provide an acoustic output.

Description

Technical field

The invention relates to a projection screen and in particular, but not exclusively, to a projection screen.

BACKGROUND OF THE INVENTION

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

US-A-5,025,474 to MATSUSHITA discloses a screen-to-loudspeaker connection where the loudspeaker has a box-like box formed with an inlet opening so that the loudspeaker functions as a bass-reflex loudspeaker to enhance its performance at low frequencies.

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

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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, dated the same date. Such members have the ability to maintain and propagate the input vibration energy by bending waves in the operating region or in the operating regions 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 resonant modes distributed in this region, preferably for acoustic communication with the environment and predetermined preferred 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. The use is envisaged in the co-pending PCT Application No. V097 / 09842, from the same date, for these members as or in passive acoustic devices without converters, as reverberation or acoustic filtering 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 a projection screen with a built-in acoustic device, for example in the form of speakers.

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.

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The invention consists of a projection surface consisting of a panel with a light reflecting or radiating surface, the principle being that the projection surface is formed by a member capable of maintaining and propagating the input vibration energy by bending waves in at least one operating region extending transversely to its thickness with components resonant mode vibrations distributed at least in this region and with predetermined preferential locations in the region for locating 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 formed by a rigid lightweight panel with a lightweight core arranged sandwiched between the two high module cover layers. The core may consist of a honeycomb structure of aluminum foil. The cover layers may consist of fiber-reinforced plastic. The projection surface 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. Panel loudspeakers may be attached to opposite sides of the support frame to produce left and right side information. The left and right loudspeakers may be hinged to the support frame hinged against the radiator panel, in a storage position. The left and right loudspeakers may be formed by a member capable of maintaining and propagating 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 locating the transducer, the transducer mounted on the member at one of these locations, to cause the member to vibrate, to generate its resonance generating acoustic radiation panel, creating during φ φ φ φ φ φ · · · · · · · · φ φ φ φ φ φ φ φ φ φ φ φ

- 4 resonance acoustic output. The screen may be a screen.

In another aspect, the invention is an audiovisual device having a projection screen. The audiovisual device may be provided with at least one rear channel loudspeaker comprising a member capable of sustaining and propagating energy and bending waves in at least one thickness operating region, resonant mode vibration components distributed at least in this region, and predetermined preferred locations in that region for positioning the transducer, the transducer being mounted fully and exclusively on the member at one of these locations to cause the member to vibrate to generate its resonance generating an acoustic radiating panel, producing an acoustic output during resonation.

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 is an enlarged and cross-sectional view of the loudspeaker of FIG. 2a showing two alternative structures; FIG. 3 is a schematic and perspective view of an embodiment of a screen according to the present invention; FIG. and FIG. 5 is a plan view of a room equipped with a screen according to FIG.

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 shows a panel loudspeaker 81 of the type described and claimed in our co-pending International Application No. WO97 / 09842 from the same date, which is provided with a rectangular support frame 1 surrounding its inner circumference with a flexible frame 3 supporting the unfolded The loudspeaker 81 is further provided with a transducer 9, which is described in detail 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 the x and y coordinates. whose position 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 panel resonation, to generate an acoustic output.

The transducer 9 is excited by a signal amplifier 10, for example a low-frequency amplifier, connected to the transducer 9 via wires 28. The load and power requirement of the amplifier 10 may be quite normal, as with conventional cone loudspeaker types, with 86 to 88 dE! / W sensitivity in room conditions. 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 supporting 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 supporting frame are lightweight frame structures, for example, picture frames of extruded metal, for example aluminum alloys or of plastics. Suitable materials for the flexible frame are resilient materials such as foam rubber and foam plastics.

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Suitable adhesives for glued joints 20 are epoxy, acrylic and cyanoacrylic adhesives, etc.

In Fig. 2b it is shown on an enlarged scale that panel 2 is a rigid light panel, consisting of a core 22, for example a rigid plastic foam of cross-linked polyvinyl chloride or a lightweight construction

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i.e., a honeycomb structure of metal foil, plastics or the like, with chambers extending transversely to the plane of the panel 2, the core being enclosed between opposing cover layers 21 of, for example, cardboard, plastic or metal foil or sheet metal. When the cover layers 21 are of plastic, they can be reinforced with fibers, for example carbon, glass and Kevlar (CRTM) or the like, in a manner known per se, to increase their modulus.

Thus, envisaged materials for the liners and reinforcements include carbon, glass, Kevlar

CRTM)

Nomex CRTM), i.

aramid and similar fibers in different layers and weaves, as well as paper, laminated paper, melamine and various synthetic plastic films and high modulus such as Mylar (RTM), Kaptan CRTM), polycarbonates, phenol plastics, polyesters or related plastics and plastics reinforced fibers, 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. Injection of these and other thermoplastics further allows the positioning and aligning features such as grooves or rings to accurately position the components of the transducer, such as a coil and a magnet suspension, in the injection molding tools.

For some materials for

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999 weaker cores are furthermore considered to be advantageous to locally increase the thickness of the cover layer, for example in the region of the annulus, up to 150¾ the diameter of the transducer, to amplify this region and advantageously double the vibration energy of the panel.

In this way, the response of the high frequency is improved by the softer foam material.

Supposedly, the core layer materials include industrially made honeycomb or corrugated aluminum alloy sheet or foil construction.

or

Kevlar

CRTM), Nomex CRTM), uncoated paper or cardboard and various synthetic plastic films, 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. High performance lightweight core material is known under

Rohacell, which may be suitable as a trade name radiant panel, and which is free of covering layers.

Practically speaking, the purpose is an overall light and rigid material suitable for special purposes, in particular to incorporate the utmost benefit of the layer for the cores and cover layers and the transition therebetween. Some preferred panel compositions include metal and metal alloy coating layers or alternatively carbon fiber reinforced materials.

Both these materials and the structure with alloy

Aerogel or with a honeycomb metal core have important RF shielding properties that should be of importance in some EMC CEletromagnetic applications

Electromagnetic compatibility). Conventional cone-type panels or loudspeakers do not have their own electromagnet capability. sic teach 1 nose even in shielding. In addition, the preferred embodiment of the piezoelectric or electro-dynamics currencies and the electromagnetic radiation or negligible magnetic field are negligible. 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, the electrical connections of the conductive portions of the relevant DML CData Manlpulation Language (DML) 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-dimming. 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, particularly with respect to finer effects and / or mid and high frequencies, can be attached to the layers at predetermined intermediate positions in the region in the form of suitable materials.

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The acoustic panel described is two-dimensional. The sound energy from his rear face is not strongly phased with the energy from his front face. This results in the benefit 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 standing waves, 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-ventilated, the percentage of phase information increases off-axis. For enhanced focus on artificial stereo, the position of the announcer, and 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 sound emitted by the acoustic panel gives it a sound volume that does not follow the law of indirect source dependency. Because the square of the distance for the equivalent point intensity with decreasing distance is much lower.

than given by the law of indirect dependence on the square of the distance, then, as a consequence, 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 an 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 lowering the volume from the proximal speaker accordingly.

Another advantage of the flat light panel speaker is that it is visually attractive, has good sound quality and

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999 999 99 99 9999 requires only the transducer and not the speaker crossover for the full range of sound from each panel membrane.

Fig. 3 shows a multimedia audio-visual system comprising a film projector 31 adapted to project an image onto a projection screen 32 comprising a loudspeaker panel of the type shown in Figs. 1 and 2.

The projection screen 32 with the loudspeaker consists of a panel 2 consisting of aluminum or reinforced carbon fiber cover layers 21 between which a core 22 consisting of a honeycomb structure of aluminum foil is sandwiched. The composite plate may be joined by any epoxy adhesive. II. A screen size of 1.22 x 1.38 m in panel size may be 300 microns of aluminum covering layers. The thickness of the core may be 11 mm and the size of the cells of the honeycomb structure may be 9.5 mm. Such a panel is rigid, low density, high modulus and isotropic.

To the opposite sides of the primary screen 32,

formed panel with a loudspeaker, they are hinges 34 attached two smaller auxiliary panel speakers 114, type, which is 1 and 2. These auxiliary panel

the speakers 114 may be tilted against the primary projection screen 32 when not in use, and may extend to an operating position as shown in FIG. These sub-panel loudspeakers 114 are configured to receive and radiate respective left and right information, for example, in stereo operation. The auxiliary panel loudspeakers 114 may consist of panels 2 provided with aluminum foil or plastics reinforced layers 21 which are reinforced with carbon or glass fibers. A decorative foil, for example of polyester, may be applied to one or both of these cover layers. The core 22 of the auxiliary panel loudspeakers 114 may be made of plastic film, for example in the form of a honeycomb structure, or may be

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11 ** Paper - When paper is used, it can be impregnated with a plastic material, such as a phenolic compound, to increase the stiffness of the paper. The size of the chambers may be in the range of 3 to & mm and the thickness of the core 22 may be 3 to 10 mm. When the cover layers 21 are of aluminum foil, they may have a thickness of 25 to 100 microns. An epoxy adhesive may be used to join the panel.

Stereo reproduction, i.e., two-channel sound reproduction, means creating a state of sound illusion, including the properties of the location of the sound source, the spatial arrangement, and the environment of the original recording. Stereo broadcasting with conventional speakers is important in terms of the artificial location of the sound source and, in some cases, the spatial arrangement, but is weaker in terms of the expression of natural space and environment. This is because the near-point nature of the sound source of a conventional piston loudspeaker facilitates aural definition of its physical position, which is contrary to the requirement to locate the overall stereo acoustic image.

It is often said that loudspeakers, as a reproducing device, should dissolve into a state of sound illusion. Part of this problem lies in the relatively narrow forward-radiating directivity of conventional speakers. In addition, the sound balance towards the sides and the rear face of the loudspeaker housing, the sound that strongly affects the sound field of the reverberation in the room, is colored and unbalanced by significant variations in the frequency response. This reduces the feeling of natural acoustic space and environment.

In the embodiment of FIG. 3, a pair of left and right channel acoustic panel loudspeakers is used, which are set to complex vibration across the entire area over a wide frequency range, typically 100-20 kHz. The central projection screen 32, consisting of a loudspeaker panel as shown in FIG. 3, is hinged to the suspension means 33, but may alternatively be supported, for example, by a stand.

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Figure 5 shows how it can be. The projection apparatus according to the invention is arranged in a room 145 equipped with seats 146. The apparatus has a film projector 31 for projecting the image onto the screen 32, and also has a pair of auxiliary depth speakers 35 arranged on the sides of the room which may be of conventional construction to improve bass and a pair of rear effect loudspeakers 117, i.e., so-called environment reproduction loudspeakers arranged at the rear of the room. Suitable rear effect loudspeakers 117 are also loudspeakers of the type shown in FIGS. 1 and 2 in respect of their broad and uniform sound propagation properties. These rear effect loudspeakers 117 may be of the same design as the sub-panel loudspeakers 114.

The panel speaker of FIGS. 1 and 2 has remarkable non-directed properties. For acoustic reproduction of the sound system environment, energy must be widely distributed, ideally from non-directed sources. It is important that the sound source is not well located, otherwise the perception of the large surrounding space and the simulated acoustic area behind the listener are not satisfactory.

To date, conventional routed or low source range speakers, usually moving coil speakers, have been used for acoustic reproduction of the environment. Due to the intensity of auditory perception, listeners seated close to the adjacent loudspeaker for the reproduction of the environment have a strongly localized perception of this loudspeaker, which greatly worsens the effect of the environment and its overall appreciation of the multichannel sound field.

Localization can be so strong that the audience's attention is diverted from the primary front audio channels, which is related to the Haas effect, which amplifies localization of closer sources.

Environmental reproduction system, built with one or two

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1 and 2, it delivers a large sound field or an almost uniform intensity that deliberately has a poor start.

Can accommodate a large number of listeners.

even several (closest to 0.5 m) for panel speakers without any significant localization of the immediate reproductive channel and with the necessary ability to aurally perceive important front channels. With this multi-channel audio reproduction system, a strongly improved realistic listening experience as a whole is achieved as a result of the desired radiating characteristics of the acoustic panel acoustic speaker.

Environmental loudspeakers can be hung on wires if desired, and can be masked by attaching a suitable image to the panel 2, resembling the image

As shown in FIG. 4, a back cuff 36 may be formed on the support frame X of the screen panel to cover the flexible frame 3. The frames of the sub-panel speakers 114 and the rear effect speakers 117 and the rear effect loudspeakers, respectively. reproduction environments can be modified similarly.

Industrial utilization

The acoustic panel, made in sufficient size as a projection screen for slides, film projection and video projection, thus forms an audio speaker at the same time, for example, for the central or dialogue channel of a home theater.

Only the acoustic panels according to the invention, other than 0.6 m, provide very good sound coverage for the listener.

Operational performance has shown high clarity and clarity of sound throughout the audience, with the great advantage that those closest to the screen do not suffer from deafening noise of excessively close sound levels, a constant defect of conventional cone speakers,

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Furthermore, there is a second and unique aspect of the screen of the invention. With conventional center channel speakers, the ear can more easily locate the acoustic center of the speaker. All sounds seem to come from this concentrated little source, reducing the sense of realistic listening. In this acoustic panel, the unmeasured ability to radiate to mean its unique, sound comes from the general acoustic panel of the screen, but not from a single, isolated point.

When the image on this panel is combined with sound, a strong synesthetic effect occurs. The desired lack of specific sound localization here freely combines the combination of visual and rational perception with the imagined, virtual and approximate location of the sound sources, the synchronized position represented by the visual to the sound surface.

well-recorded portions of dialogue not only seem to be a virtual acoustic image following a visual image, it can also express the information required for perception of depth and distance. The quality of audience engagement in the film experience will significantly increase.

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Claims (10)

PATENT CLAIMS The left and right loudspeakers (114) are formed by a member (2) having the ability to maintain and extend the input of vibration energy by bending waves in at least one operating region, to its thickness, with resonant vision vibration components distributed at least in that region. with predetermined preferential locations in the region for accommodating the transducer, the transducer (9) being mounted fully and exclusively on the member at one of these locations to induce vibration of the member to generate its resonance forming an acoustic radiating panel (2) acoustic output during resonation. 10. A screen as claimed in any one of claims 1 to 9, wherein the screen (32) is a projection screen. • · · · · 17 11. Audio-visual equipment 12. m that contains Audiovisual projection apparatus, screen (32) according to claim 11, characterized in that A screen (32) comprising a panel (2) with a surface. Reflecting or radiating light, characterized in that the projection screen is formed by a member (2) capable of maintaining and propagating the input vibration energy by bending waves in at least one operating area, throwing transversely to its t-beam, with components and vibration. resonant modes distributed at least in this region and with predetermined preferential locations in this region for locating the transducer, wherein the currency (9) is mounted fully and exclusively at this member to one of these locations to induce vibration of the member, for deriving also its resonance forming an acoustic radiating panel (2), producing an acoustic output during the resonation. Projection screen, according to claim 1, characterized in that the radiating panel (2) is characterized by a rigid light panel with a lightweight core (22) arranged sandwiched between two high-modest cover layers (21). Projection screen according to claim 2, characterized in that it is provided with a support frame (1) arranged around the periphery of the radiating panel (2). Projection screen according to claim 3, characterized in that the radiating panel (2) is fixed in the support frame (1) by a flexible frame (3). A projection screen according to any of claims 2 to 4, characterized in that the core (22) is formed by a honeycomb structure (98) of aluminum foil. Projection screen according to claims 2 to 5, characterized in that the cover layers (21) are made of fiber-reinforced plastic. 7 or 8 Projection screen, according to the preceding claims, when dependent on claim 3, characterized in that panel speakers (114) are connected to opposite sides of the support frame (1) to produce left and right-hand information. Projection screen according to claim 7, characterized in that the left and right loudspeakers (114) are hinged on the support frame (1) hingedly against the radiating panel (2) in the storage position. A projection screen as claimed in claim 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 99 99 99 9999 ······························ 9 9 10. provided with at least one rear channel loudspeaker (117) (2) capable of maintaining and extending the input vibration energy input member 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 designated priority locations in the region for locating the transducer, the transducer being mounted fully and exclusively on the member at one of these locations to induce vibration of the member to generate its resonance, forming an acoustic radiating panel, generating an acoustic output during resonation.