Electret structure

A technology of electret and electret layer, applied in electret electrostatic transducer, fluid using vibration, etc., to achieve the effect of ensuring charge stability, strong spatial separation, and high charge stability

Inactive Publication Date: 2016-06-08
ROBERT BOSCH GMBH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, there are only few options for the selection of electrets considered for use in such harsh environmental conditions

Method used

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Embodiment Construction

[0032] figure 1 A cross-section of an electret structure 1 according to a first embodiment of the invention is schematically shown. The electret structure 1 comprises a metal carrier 10 which forms an electrode of the electret structure 1 . The charged Teflon film constitutes the first electret layer 30 . A layer 20 of a porous dielectric material, for example ceramics, polymers or porous Teflon, is arranged between the carrier 10 and the electret layer 30 , so that a sandwich structure according to the invention results. The porous medium layer 20 thus comprises a fixed medium 22 having, for example, pores 24 of different sizes. In this embodiment, a second electret layer 40 is provided between the porous medium layer 20 and the carrier 10 , and the second electret layer is provided with a metal coating 45 on its surface 42 facing the carrier.

[0033] In this example, the first electret layer has charge carriers 50 which have a negative charge. Countering charges 55 with...

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Abstract

According to the invention, an electret structure (1) is proposed which comprises an electrically conductive substrate (10), a first electret layer (30) and a porous dielectric layer (20), which is arranged between the substrate (10) and the first electret layer (30). The electrically conductive substrate (10) in this case preferably forms an electrode of the electret structure (1) according to the invention. The invention is based on the concept of using the porous dielectric layer (20) to separate the charged electret layer (30) from the electrode (10). As a result, the migration of electrical charges (50) out of the electret layer (30) towards the rear electrode (10) is impeded. Likewise, the migration of oppositely charged charge carriers (55) out of the rear electrode (10) into the electret layer (30) is impeded. The charge stability of an electret structure (10) according to the invention in comparison with conventional addons without a porous dielectric layer (20) between the electret layer (30) and the rear electrode (10) is thus markedly increased.

Description

Background technique [0001] Electrets are materials that can store electrical charge over extended periods of time. Electrets (e.g. in the form of polymer films, and inorganic electrets such as SiO 2 ) can be charged by various methods (corona method, electron beam, contact charging . . . ). During charging, charge carriers are injected into subregions of the electret or cause charge separation in the electret, whereby the electret becomes a carrier of an electric field. Charged electrets can be used in several electronic components, for example in microphones, speakers or air filters. For this purpose, the electret is connected to the electrodes on at least one side and is charged, so that an electret structure is formed. For example, in "Electrets" by G.M.Sessler (author) (Volume 1, 3rd edition, Laplacian Press, MorganHili, CA, 1999) or in "Electrets: recent developments" by G.M.Sessler (Journal of Electrostatics, Vol. 51-52, A comprehensive description of what is known ...

Claims

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Application Information

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IPC IPC(8): H04R19/01B06B1/02
CPCH04R19/01B06B1/0292
Inventor D·巴尔特伊拉N·迈尔E·希尔特
Owner ROBERT BOSCH GMBH
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