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The invention is a sound-generating sheet glass comprising a glass sheet (4), a film (3) of
absorbent material, and a hard sheet (5), the assembly being laminated and fixed to the sheet
glass Includes an exciter. [Selected figure] Figure 1
Sound generating plate glass
The present invention relates to a glazing unit used as a sound generator.
Most automatic vision devices (TV sets, computers, mobile phones) available on the market
include one display screen and at least one sound generator.
The display screen is usually coated with a protective glazing customarily formed by single or
laminated glass panels. Often the sound generator includes one or more loudspeakers separated
from the screen. The separated arrangement of loudspeakers and screens results in a bulky
In order to reduce the bulk, it has been proposed to use the screen itself as a resonator and to
mount one or more exciters thereon to form a sound generator in the entire assembly.
However, so far the realization of such an automatic visual screen has encountered a number of
difficulties associated with the production of flat glass with all the necessary qualities.
Thus, Glas Platz GmbH & Co. In the "Magic Sound (R)" technology of the company, flat glass is a
glass panel having a thickness of only 0.3 mm. The use of glass panels having such small
thicknesses is determined by the acoustic properties of the glass. With regard to mechanical
resistance, in particular impact resistance, it is not suitable for the production of screens
(computer or television screens) of large dimensions.
In the "SoundVu" technology of NXT plc, it is proposed to produce a sound-producing sheet glass
from a polymeric material having suitable acoustic properties, in particular polycarbonate.
However, in use, such glazing units have very poor optical quality and poor mechanical
resistance to scratches.
The present invention aims to overcome the problems and drawbacks of the known glazing units.
In particular, it is an object of the present invention to provide a sound producing glazing which
has both good acoustic properties, good optical quality and good mechanical properties, in
particular good impact resistance and good scratch resistance.
The invention relates to a sound generating glazing comprising at least one glass sheet and a film
of absorbent material attached to the glass sheet on one side and to the sheet of hard material on
the other side.
In the glazing according to the invention, the glass sheet, the film of material attached to it and
the sheet of hard material are at least translucent.
Preferably they are transparent to light.
They can be transparent to white light or to only part of the spectrum of white light.
In most of the applications it is preferred to be transparent to white light.
In the following description, the term "light" is generally used to mean all or part of the spectrum
of white light.
A glazing according to the invention, which acts as a resonator, comprises at least one exciter
fixed to a glass sheet or a sheet of hard material.
The exciter can be, for example, a piezoelectric type exciter.
It must have sufficient power to vibrate the glass sheet.
In principle, the exciter can be placed anywhere on the glass sheet. However, it is advantageous
to place the exciter (s) on the edge of the glass sheet. The use of several exciters distributed
around the circumference is advantageous. The exact arrangement of these exciters in the
environment is chosen depending on the resonance scheme of the glass sheet.
Regardless of the above conditions, the choice of exciter (s) is not critical to the definition of the
invention. Preferably, an extra flat exciter is used. Examples of extra flat exciters in accordance
with the invention are those manufactured by NXT plc under the name "NXT SoundVu
technology" and Glas under the name "Magic Sound" as described above. Platz GmbH & Co. It is
manufactured by KG.
According to the invention, the panel comprises at least one film laminated and made of an
acoustically absorbent material.
The glass sheet constitutes a resonator.
It vibrates under the action of an exciter that generates an audible sound.
As a result, the thickness of the glass sheet, in particular the thickness of the glass sheet, is an
important parameter. It must be determined that the glass sheet vibrates under the action of the
exciter to emit a sound of sufficient strength.
The thickness of the glass sheet depends on its coincidence frequency. In practice, the aim is to
move it towards the high frequencies of the sound waves by reducing the thickness of the glass
sheet. The thickness of the glass sheet should be chosen such that its coincidence frequency is
moved to 6 or more (preferably 10) kHz. It is preferable to reduce the thickness of the glass
sheet until the coincidence frequency is higher than the maximum frequency normally audible to
the human ear (about 20 kHz). Therefore, a thickness of less than 2 mm (preferably 1.5 mm) is
recommended. For mechanical resistance considerations, the thickness of the glass sheet is
preferably greater than 0.5 mm (preferably 0.8 mm). A thickness of 1 to 1.5 mm is particularly
The glass sheet should be at least translucent. Preferably it is transparent to light.
The purpose of the film of the panel is to ensure the acoustic quality of the panel. For this reason,
it must be made of an absorbent material.
In practice, it is necessary that the resonator formed by laminated glazing to ensure the
mechanical quality of the assembly be able to properly play its role of resonator.
Advantageously, the second sheet of rigid material in a stacked arrangement is a second glass
sheet which is similar or identical to the first sheet.
It can also be a sheet of synthetic material having the necessary optical properties of a perfect
flat glass.
The laminated glazing is mounted on a screen with glass sheets arranged to face outwards in
order to guarantee the scratch resistance best.
In fact, with regard to the lamination arrangement composed of two glass sheets joined by a
traditional interlayer sheet in a safety glazing unit, the usual interlayer sheet of the type made
from PVB (polyvinyl butyral) is a necessary property Do not give
It's too hard.
The absorption properties of a film are generally defined by its acoustic absorption or loss factor,
which indicates the amount of vibrational energy that is converted to heat, with a theoretical
maximum absorption of 100%.
In the glazing according to the invention, the film is advantageously chosen such that the
acoustic absorption of the glazing is less than 80% (preferably 75%) at 200 Hz and 20 ° C.
It is recommended that the absorption be greater than 5% (preferably 8%) at 200 Hz and 20 ° C.
Absorption rates of 10 to 50% are preferred.
Films with the required acoustic properties can also be defined by their visco-elastic properties,
on which the absorption properties depend. Shear modulus is a parameter that describes the
viscoelasticity of the product considered.
These viscoelastic properties are also temperature dependent. For convenience, the shear
modulus of the product considered by the present invention is defined at a temperature of 20 °
The shear modulus for a frequency of 200 Hz at a temperature of 20 ° C. is advantageously less
than 10 <6> Pa.
According to the invention it is preferred that the glass sheet gives an average absorption of 12%
or more, in particular 20% or more, over the entire frequency range of 200 to 4400 Hz.
Furthermore, this average absorption has to be achieved for the actual temperature of use. In
practice, for example in television screens, the usual temperature varies from 20 ° C to 40 ° C.
The maximum average absorption should be ensured over this entire temperature range.
The "average" absorptivity of the glass sheet, which is determined at all frequencies between 200
and 4400 Hz for a given absorbent film, changes only in a limited range over the operating
temperature range. The variation in average absorption over the temperature range of 20 ° C. to
40 ° C. should not exceed 35%. Preferably it should be less than 25%.
The film should be translucent. It is preferably clear to light.
Examples of materials that can be used for the film include ethylene-vinyl acetate copolymer and
polyurethane. In all laminated arrangements involving two rigid sheets, in particular two glass
sheets, it is advantageous to use a film made of polyvinyl butyral, where the plasticity adds the
appropriate type of plasticizer in an appropriate amount Is increased by In the safety glazing unit
the plasticity of the middle layer is limited to maintain significant mechanical resistance to the
overall lamination arrangement, but this condition is less important for acoustic applications and
the product has much higher plasticity it can.
Films which can be used according to the invention are described in particular in the patent
documents EP 517114, WO 01/19747.
For example, a composite film comprising two standard PVB layers can also be used to bond
them to a glass sheet, these two layers sandwiching a layer of material according to the acoustic
absorption properties of the invention.
This layer can itself be made of "over-plasticized" PVB. Products of this type include, for example,
those available from Sekisui under the name S-LEC. Layered products of this type are the subject
of patent documents such as EP 457190, EP 566890 or EP 710545.
The glazing according to the invention is most often used in screens or assemblies for image
display purposes. This screen forming assembly can form a second rigid sheet of sheet glass
according to the invention, as long as it is added to an assembly such as that used to form a
laminated sheet glass unit.
Assembly can be achieved by exploiting the thermoplasticity of the absorbent film. A suitable
resin can also be used to form a laminate arrangement, the crosslinking being formed directly
between the rigid sheets (between the glass sheet of the glass sheet and the second rigid sheet or
the panel forming the screen). Products of this type are e.g. epoxy resins such as those used in
sound insulation glazing units.
Regardless of the above-mentioned properties which should be possessed, the choice of the
material of the rigid sheet is not important to the definition of the invention.
Examples of materials that can be used for rigid panels include in particular synthetic or mineral
glasses such as polyacrylates or polycarbonates.
The dimensions of the glass sheet and its components (film, glass sheet, second hard sheet) are
not critical to the definition of the present invention.
They will depend on the application for which the sound-producing glazing according to the
invention is intended.
In general, it is advantageous for the glass sheet to have a total thickness greater than 1 mm in
order to have sufficient mechanical resistance.
It is desirable to avoid excessive thickness for reasons of weight, bulkiness and cost. A thickness
of less than 8 mm is recommended, a thickness of 2.5 to 5 mm is preferred.
The glazing according to the invention can have any shape that can be adapted to the ultimate
purpose of the glazing. It is generally flat but can also have a shape that is curved around one or
more axes.
The glazing according to the invention combines a series of properties that were previously
considered to be nonconforming. On the other hand, the glass sheet gives it favorable optical and
mechanical properties, in particular scratch resistance, and its combination with a film made of
an acoustically absorbing material gives it good acoustic properties. On the other hand, flat glass
formed from film and glass sheet in combination with the screen panel or second sheet ensures
favorable mechanical resistance.
The sound producing glazing according to the invention has various applications in the
manufacture of image display devices such as televisions, portable computers, mobile phones,
home cinema devices, or screens for physical and / or chemical analysis devices. It also has the
application of both protection and sound generation "communicating" flat glass (for music or
audio data), in particular for business or museum, bus shelter, ceiling, mirror or decorative glass,
advertising panel or partition, image frame , With applications for flat glass units for, but not
limited to, loudspeakers.
Therefore, the present invention also relates to an image display screen characterized in that it
comprises a sound-generating glazing according to the invention as defined above. According to
the invention, the expression "display screen" refers to any screen that can have an image. The
term "image" has a broad definition and relates not only to graphical representations of objects
but also to alphabetic characters and symbols.
For example, the screen according to the invention can comprise a sheet or panel on which an
image is drawn and / or painted.
In another example according to the invention, the screen comprises a sheet or panel of uniform
color (e.g. white) intended to receive an image projected from a suitable projector, or a support of
an element generating this image.
The invention relates in particular to a display screen of the above type intended for installation
in an image generator selected from physical or chemical analyzers, televisions, computers and
mobile phones.
In this application of the invention, the screen comprises a panel coated with a fluorescent film to
provide a panel with a liquid crystal assembly or a cathode tube, as is well known in the
manufacturing art for computers and televisions.
The sound producing glazing according to the invention can also be applied to the building
industry, where it can serve as a glazing for windows, in particular as a display window for
stores, hotels or restaurants, but not limited thereto. .
Therefore, the invention also relates to the use of the glazing according to the invention as
glazing of buildings.
Particular features and details of the invention will become apparent from the following
description of the attached drawings.
FIG. 1 is a schematic exploded perspective view of a specific example of a glazing according to
the invention.
FIG. 2 is a view similar to FIG. 1 of the second practical example of the present invention.
FIG. 3 is a graph showing the average absorption (%) as a function of temperature for three
Figures 4a and 4b show two arrangements for positioning the exciter relative to the glass sheet
forming the resonator.
FIG. 5 is an illustration of an apparatus used to measure absorptivity.
The glazing according to the invention is given the general reference 1.
The glass sheet 1 is applied to the screen 2 of the portable computer shown shaded and covers it
completely. The screen 2 is, for example, a liquid crystal screen as is well known in the computer
and computer monitor manufacturing technology. The panels forming the front of the screen are
for example made of glass or translucent plastic material.
In the example of FIG. 1, the glass sheet 1 comprises a flat film 3 sandwiched between a glass
sheet 4 and a glass sheet 5. The glass sheet 5 is flat and has essentially the same dimensions as
the screen 2. It can be applied directly to the screen 2. Alternatively, the glass panel 5 can be
held slightly away from the screen 2 by an interlayer frame (not shown). The glass panel 5 can
have the same thickness as the sheet 4 or a thickness substantially larger than this, the main role
of which is to assemble the necessary mechanical properties, in particular when the sheet 4 is
very thin. It is to give to.
The glass sheet 4 is flat and has the same dimensions as the panel 5. It is surrounded by a frame
6 in which a piezoelectric exciter (not shown) is inserted. These piezoelectric exciters vibrate the
glass sheet 4 and generally the glass sheet assembly (glass sheet 4, absorbent film 3, second hard
sheet 5) in a manner that can emit sound waves in the audible spectrum (about 20 Hz to 20 kHz)
It is known for. The glass sheet 4 has a thickness of, for example, about 1.1 mm.
The exciter is in contact with one of the faces of the sheet 4. They are between the frame 6 and
the sheet 4 (in this case they are fixed in place after lamination of the assembly of the two sheets
4 and 5 and the absorbent sheet 3) or on the side in contact with the sheet 3 Will be placed in
any of. In this case, the insertion can be carried out before lamination as long as the exciter (s) in
question have a thickness compatible with this assembly. Also, preferably the seats 3 for these
exciters can be provided with seats before carrying out the lamination.
Alternatively, the exciter can be fixed to the rigid sheet 5.
The film 3 is sandwiched between the glass sheet 4 and the glass sheet 5.
It is made of an acoustically absorbent polymeric material having an acoustic loss factor of about
0.3. Furthermore, it must be transparent to white light.
The film 3 can for example be made of ethylene-vinyl acetate copolymer and can have a
thickness of 0.4 to 0.8 mm.
In a variant of the glass sheet shown in FIG. 1, the film 3 is made of polyurethane and its
thickness is about 0.7 to 0.8 mm.
In another variant of the glass sheet shown in FIG. 1, the rigid panel 5 is made of polycarbonate
and its thickness is about 1 mm.
In the glass sheet shown in FIG. 1, the glass sheet 4 gives the glass sheet high scratch resistance
and good optical properties.
The combination of the glass sheet 4 (of thin thickness), the absorbent film 3 and the hard glass
sheet 5 gives the sheet glass good acoustic properties and ensures the mechanical resistance of
the sheet glass 1.
The variant of FIG. 2 comprises components of a glass sheet, wherein the glass sheet 4 is
attached to a film of acoustically absorbent material and fixed directly to the panel forming the
screen 2.
In this embodiment, the formation of the film 3 from the in situ crosslinked resin, in particular
between the glass sheet 4 and the screen 2, is advantageous in that it can be achieved without
assembly operations requiring an increase in temperature. It is.
Because this is generally not possible with the electronic components of the screen in question.
Different absorbent films (A, B, C) were tested for their properties at temperatures of 20 ° C to
40 ° C. These films are contained in a laminated assembly formed of two glass sheets, each
having a thickness of 1.1 mm. Films A and C have a thickness of 0.76 mm. Film B has a thickness
of 0.50 mm.
The technique used for the measurement of the absorptivity is that described for the standard
ISO / PAS 16940. Specific conditions are shown below.
The device used is shown schematically in FIG. The analysis sample 9 inserted into the
temperature control chamber 8 (temperature controller 18) is supported by the support 10 at its
center. It is fixed to this by means of an adhesive 12. The excitation is transmitted to the sample
9 via the support 10 by means of the vibrator 19.
The circuit comprises a noise generator 17, an output amplifier 16 and an impedance head 11.
The analysis is performed by the impedance measuring amplifier 13 and the calculation system
15 associated with the FFT analyzer 14.
The sample tested consists of 230 × 12 mm laminated test strips, the total thickness of which
depends on the type of absorbent film. The samples are subjected to vibrational excitation (Bruel
& Kjaer type 4810 vibrator) operating in a "white noise" mode (Bruel & Kjaer type 1405 noise
generator). Under the influence of the excitation, the mechanical impedance of the sample is
measured (Bruel & Kjaer type 8001 impedance head) and different resonant frequencies are
determined (ONO SOKKI type CF-910 frequency analyzer).
The absorption rate η is determined by the following equation. η = Δf n / f n where f n is the
resonance frequency considered and Δf n is the width of the resonance curve at -3 dB.
The measurements are made over the full range of frequencies from 200 to 450 Hz. The values
obtained are averaged.
The measurements are made at a temperature which represents the general mode of operation
under normal operating conditions of the television type screen. Three measurements are taken
at 20 ° C., 30 ° C. and 40 ° C. respectively.
Absorbent films tested are each a polyvinyl butyral film traditionally used in laminated sheet
glass unit applications intended for the construction sector, and two films known to be used in
sound insulation sheet glass units It is.
Laminated specimens made from traditional PVB designated A have no acoustic quality.
It is relatively hard. The film of the tested flat glass sample designated B is a composite formed of
two PVB films of reduced thickness separated by a film having a plasticity substantially higher
than that of PVB. The film designated C is formed from highly plasticized PVB as a result of the
addition of the plastic component.
The measurement results are recorded as a function of temperature and frequency in the
following table marked A, B and C. The last table shows the average absorptivity values at
different temperatures. The results are also shown in FIG. 3, which shows absorption as a
function of temperature.
In this figure, it can be seen that the absorption for samples made from traditional PVB is
relatively low at the temperatures considered. It is only noticeable at higher temperatures. The
two other products give considerably higher absorption rates, which, in contrast to the previous
products, drop when the temperature rises significantly. In the range of 20 ° C. to 40 ° C.,
these two products meet the general conditions of the invention.
<img class = "EMIRef" id = "330677014-000003" />
<img class = "EMIRef" id = "330677014-00004" />
<img class = "EMIRef" id = "330677014-000005" />
<img class = "EMIRef" id = "330677014-000006" />
The absorptivity of products containing films B and C is clearly higher than 12% at all conditions
and higher than 20% for most normal temperature conditions.
Furthermore, for each of these sheet glass units B and C, the absorptivity as a function of
temperature does not change by more than 35% and remains below 25%.
Figures 4a and 4b show two possible types of structures.
These two figures differ in the positioning of the exciter 7 with respect to the glass sheet 4.
The figures only show one exciter in each case.
In fact, the glazing units according to the invention can each have several exciters. This is
particularly useful as the sheet's resonance depends on the positioning of the exciter relative to
As shown, the exciter 6, or one of them, can be arranged on the face of the sheet 4 (FIG. 4a). In
the same way, one or more exciters can be arranged on the edge of the sheet 4. This latter
arrangement has several advantages from an acoustical point of view and furthermore makes it
possible to completely demount the glass sheet from any element which hides the presence of
these exciters.
4a and 4b show an exciter fixed to the glass sheet 4, which can also be fixed to the associated
hard sheet 5. FIG. The choice depends at least in part on the ease of positioning of these exciters
with respect to the glass sheet, but also takes into account the special features of resonating the
glass sheet.
FIG. 1 is a schematic exploded perspective view of a particular example of a glazing according to
the invention. It is a figure similar to FIG. 1 of the 2nd actual example of this invention. Figure 2
is a graph showing the average absorption (%) as a function of temperature for three materials. 2
shows two arrangements for positioning the exciter with respect to the glass sheet forming the
resonator. FIG. 2 is a diagram of an apparatus used to measure absorptivity.
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