Abstract: A color cathode ray tube of the shadow mask or beam index type in which the screen structure applied to the faceplate has a plurality of triplets of optical interference filter stripes which are adapted to pass red (R), green (G) and blue (B) light produced by a homogeneous cathodoluminescent screen layer. The usual aluminium layer may be applied to the screen layer. The optical interference filter stripes may have short wave pass filters, band pass filters or a combination of both types. The short wave pass filter stripes may have modified quarter wavelength multilayer dielectric filters and the bandpass filter may have a Fabry-Perot filter.

Abstract: An electron beam recording medium with a coating, which is applied to a substrate, is sensitive to electron beam radiation and has an organic rare earth metal type phosphor, is suitable for the irreversible writing of information with low-intensity electron beams.

Abstract: An electroacoustic transducer comprises a terminal (1-1'), a voice coil (2) coupled to the terminal, and a diaphragm (4). The transducer further comprises an element (other than the voice coil) made of a superconducting material which cooperates with the voice coil (2) to provide electromechanical conversion of an electric signal appearing at the terminal (1-1') into vibrations of the diaphragm, or vice versa.

Abstract: Projection television display tube comprising an evacuated envelope having a display window provided on its inside with a display screen, a transparent second window which is disposed in front of said display window on its outside, and a transparent coolant flowing through the space between the display window and the second window, said coolant conveying the heat taken up at the display window through a cooling member to the atmosphere. The coolant is also in thermally conducting contact with a latent heat accumulator, so that an effective cooling is obtained even at peak loads of more than 40 W, and without external pipes.

Abstract: A projection television display tube having an evacuated envelope (1) with a display window (4) which has a display screen (5) on its inside and in front of which a light-permeable second window (6) is provided on the outside, a cooling liquid flowing through the space (7) between the display window (4) and the second window (6) from at least one inlet aperture to at least one outlet aperture. When in such a projection television display tube a cooling jacket(8) is provided at the area of the windows (4, 6) and around the said space (7) and is provided with at least one duct (9) and one pump (16) with connecting nipples (17,18) which transport the cooling liquid from the outlet aperture to the inlet aperture or apertures of the said space (7), an effective cooling is obtained with a power up to 40 W without outer pipes and without heat exchangers. By the forced circulation of the cooling liquid a good temperature compensation is obtained so that fewer stresses occur in the glass of the display window.