Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Patent
1997-11-03
2000-02-08
Budd, Mark O.
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
310324, 310334, 310316, 310326, 381190, H01L 4108
Patent
active
060231238
DESCRIPTION:
BRIEF SUMMARY
The invention relates to an arrangement for effecting acoustic vibrations in a medium, for instance air, at least comprising a substantially sheet-shaped body for transmitting the vibrations to the medium, provided with at least one actuator that can be connected to a signal generator.
DISCUSSION OF THE BACKGROUND
Arrangements of this sort, also called sound generators, are sufficiently well-known in the art, particularly owing to their application as loudspeaker for playing music. A sound generator can, however, also be used for generating anti-sound. Sound waves acting from outside sources on an enclosed space can often be effectively attenuated by recording these waves with a sound recorder and by subsequently transmitting them in phase opposition to a sound generator.
SUMMARY OF THE INVENTION
The object of the present invention is to integrate in an inventive manner a sound generator in a windowpane, in particular for application in a building, but also in a vehicle or a vessel. Instead of or in addition to window glass, use is also made of transparent synthetic materials which can be applied as a thin layer of foil. The advantage of this is that most buildings contain plenty of window glass or suchlike materials which, owing to their flexibility, are excellently suitable for generating acoustic vibrations. Use can be made of window glass or suchlike materials which is for instance on the outside provided with a mirror coating in order to exclude disturbing sunlight or to prevent people from looking in. The use of window glass or suchlike materials as sound generator eliminates the necessity to incorporate loud speakers.
In order to realize the above inventive principle, said arrangement is characterized in that the at least one substantially sheet-shaped body comprises at least one surface that is substantially transparent to visible light in one or two directions.
An advantageous embodiment is based on double-glazed windows which are widely used for their insulating properties. This offers possibilities for incorporating, in a simple manner, the required actuator(s) in a window.
This exceptional embodiment of the arrangement according to the invention is thereto characterized in that the at least one body comprises two substantially parallel windowpanes which enclose a certain space.
In this case, one windowpane preferably has a substantially higher vibrational rigidity than the other windowpane. Thus, a directional sensitivity is realized. The generated acoustic vibrations are then substantially transmitted on the side of the windowpane having low vibrational rigidity. The windowpane combination can then be fitted in a house or building such that the window having low vibrational rigidity is on the inside.
In the embodiment comprising two parallel windowpanes, an actuator can now be added in a simple manner by applying an electrically conductive layer to both windowpanes, for instance in a vapour deposition process. By applying a voltage difference over both layers that varies with the signal strength supplied by the electric signal generator, the two windowpanes will either repel or attract one another, depending on the signal shape applied. The amplitude of the voltage difference shall be sufficiently high, generally in the order of kilovolts.
An advantageous embodiment is thereto characterized in that the two windowpanes are at least partially provided with an electrically conductive layer, which two electrically conductive layers in combination constitute the actuator during the creation of a voltage difference between the two layers.
In a further advantageous embodiment comprising two parallel windowpanes, a piezo element is used as actuator. By positioning the piezo element in the space between the two windowpanes and mechanically connecting the element to both windowpanes, an actuator is obtained which, in combination with the two windowpanes, is capable of realizing a high sound pressure level.
This embodiment is thereto characterized in that the actuator comprises a piezo element posi
REFERENCES:
patent: 4048454 (1977-09-01), Barcus et al.
patent: 4352961 (1982-10-01), Kumada et al.
patent: 5357578 (1994-10-01), Taniishi
patent: 5400414 (1995-03-01), Thiele
Budd Mark O.
Hollandse Signaalapparaten B.V.
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