In order to allow various video signal sources, such as video tape recorders, to be selected for feeding a studio or other installation, a selection apparatus comprises switching apparatus and a time base corrector. The switching apparatus is disposed between the time base corrector and the recorders, and distributes subcarrier and advance sync signals to the recorders while receiving video and audio signals from the recorders and supplying those from the selected recorder to the time base corre...

A reflector for photographic sources of light, whereby an umbrella-like frame that includes struts can be placed on a mounting for a light source. A connection element is provided on the ends of the struts. A flexible reflector sheathing is disposed on the frame and has a light-discharge opening remote from the mounting. The light-discharge opening has an edge region therearound. A closure member is provided along the edge region of the light-discharge opening, with this closure member being ada...

An electron-bombardment ion source includes a chamber into which a propellant is introduced. The propellant is ionized by means of electrons drawn toward an anode from a cathode. At one end of the chamber is an apertured screen followed by an aligned apertured grid. The grid is maintained at a potential that accelerates the ions out of the chamber through the screen and the grid and past a space-charge-neutralizing cathode. A resistor is connected between the grid and the neutralizing cathode in...

Charged particles from a line emitter are focussed as a line image on a means for selectively blocking part of the image to produce a flat beam of controllable length. The blocking means may be an apertured plate with means for rotating and/or translating the image relative to the aperture to produce the required beam length. After passage through the aperture the beam may be twisted and/or translated to its original or some other orientation and position. The beam may be of electrons or ions an...

An electron-bombardment ion source includes a chamber into which a propellant is introduced. The propellant is ionized by means of electrons drawn toward an anode from a cathode. At one end of the chamber is an apertured screen followed by an aligned apertured grid. The grid is maintained at a potential that accelerates the ions out of the chamber through the screen and the grid. A surface within the chamber, such as the screen, the wall of the chamber or both, and other than the anode and catho...

The subject of the present invention is a device suitable for using sources of piezoelectric tension and particularly suitable for transforming a mechanical operation of compression, carried out on piezoelectric crystals, into a series of electrical discharges, which can be used for manifold purposes. The device is characterized by including: A. an internally hollow framework with two opposed supports, at least one support being adjustable, B. at least one piezoelectric element resting and pivot...

An electron-bombardment ion source includes means defining a chamber for containing an ionizable gas together with means for introducing such gas into that chamber. Disposed therein is an anode and an electron-emissive cathode. The potential impressed between the anode and the cathode to effect electron emission at a sufficient velocity to ionize the gas. Also included are means for accelerating ions out of the chamber together with means for establishing a magnetic field within the chamber that...

Organic fluoride sources comprising a tetrafluoroborate salt and capable of releasing fluoride ions into dentition in order to provide inhibition and/or prevention of dental caries are disclosed. A method of releasing fluoride ion into dental tissue is also disclosed.

A hollow cathode ion source for in a vacuum chamber wherein it comprises a cylindrical cathode through one end of which a gaseous medium of at least a discharge maintaining gas or said discharge maintaining gas and a metal vapor is or are introduced, and an anode provided on the other end of said cylindrical cathode and having at least one ion extraction opening, said gaseous medium being ionized by a discharge means between said cylindrical cathode and said anode to produce ions which are extra...

A circuit for "fast" switching in television system when there are more than two video sources (1, 2, 3) to be switched simplifies the realization of the change-over switches (5, 6) by replacing one or a plurality of fast change-over switches by a slow change-over switch (6), which is possible if the control signal (7) of the slow change-over switch (6) is maintained during at least one field with the aid of a timing circuit (9).