Optical element with variable transmission and screen with such an optical element

摘要

The invention relates to an optical element, comprising an essentially plate-shaped substrate (S) with a first large area formed as a light entry surface and a second large area formed as a light exit surface, a liquid or a framework matrix (F) which is arranged between the first and second large area and contains up to 60 percent by volume electrophoretically or magnetophoretically movable particles of a first type (PA), with a large number of particles of the first type (PA) being present, which absorb light of one or more wavelengths or wavelength ranges, planar on one or both large areas and / or electromagnetic switching means formed between the large areas in the substrate (S) which, when switched on, generate an electromagnetic field effective between the large areas, whereby the particles of the first type (PA) are moved in the liquid or the framework matrix (F) so that yourself a Angle-dependent transmission of the optical element for light of the wavelengths or wavelength ranges that are absorbed by the particles of the first type (PA), which enters the substrate (S) via the light entry surface, changes, so that by means of the electromagnetic switching means and a control circuit at least two Operating states B1 and B2 are defined, wherein in addition to the particles of the first type (PA), particles of a second type (PB) are also contained in the liquid or framework matrix (F) and the particles of the second type (PB) light of one or more wavelengths or reflect and / or scatter and / or transmit wavelength ranges, furthermore all electromagnetic switching means being arranged as planar electrodes EPN with polarity reversible between positive and negative on the first and the second large area, with negatively polarized ones viewed along a surface normal of the first or second large area Electrodes EPN a On the first large area, negatively polarized electrodes EPN on the second large area and positively polarized electrodes EPN on the first large area opposite positively polarized electrodes EPN on the second large area, and with a negatively polarized electrode in a preferred direction between two positively polarized electrodes EPN on each of the large areas EPN and a positive electrode EPN is arranged between two negatively polarized electrodes EPN, unless a vacancy without an electrode is arranged between two positively polarized electrodes EPN or two negatively polarized electrodes EPN, the vacancies being arranged periodically, the particles of the first type (PA ) each one and the particles of the second type (PB) have the other electrical charge polarity, in both operating states B1 and B2 more than 70% of the particles of the first type (PA) each localized between the positively polarized electrodes EPN and complementary more than 70% of the particles of the second en type (PB) are each localized between the negatively polarized electrodes EPN, or vice versa, and in the first operating state B1 the particles of the second type (PB) are each localized between homopolar electrodes that are each connected to