DE1169499B - Storage electrode for television tubes - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Boarding school Kl .: H04n;

HOIj

German KL: 21 al-32/35

Number:
File number:
Registration date:
Display day:

F 37511 VIII a / 21 al
3rd August 1962
May 6, 1964

The invention relates to storage electrodes for television pickup tubes, which on the one hand Scanned side with an electron beam and on the other side by a stream of electrons, z. B. a photoelectron stream. Such double-sided storage electrodes are z. B. used in the well-known Superorthikonröhren and consist of a thin glass membrane, which is held in a metallic frame. With such image storage tubes occur for a long time Operation or when recording high-contrast scenes, afterimages are due to the fact that the sodium atoms contained in the glass in that generated by the charges on both sides of the film electric field carry an electric current, causing sodium ions to migrate and leads to an accumulation of the same on the negative side of the foil. This changes the conductivity the slide. The afterimages are stable for a long time and have so far been made more uniform Photocathode exposure eliminated. However, if the tube is operated for a long time, the afterimage becomes apparent so fixed that it can no longer be erased.

Attempts have already been made to glasses with an electronic Manufacture component of electrical conductivity, the reversible process of electronic Line should avoid the formation of an afterimage. However, such glasses are difficult because the valency of the metal oxides used is difficult to control.

Attempts have also already been made in supericonoscopes to reduce the burn-in phenomena on conductive Glass, which is used as the dielectric of the storage electrode, to avoid that the cover rail consists essentially of a halogen compound containing sodium and / or lithium consists.

According to the inventor's experience, however, such a layer does not prove itself in continuous operation, since halogens are released from the cover layer by electron beam bombardment, which either cause poisoning of the cathode or at least the formation of a disruptive ion spot.

According to the invention in an image pickup tube with a target made of glass or a glass-like one Substance on which an alkaline, in particular lithium-containing layer is applied, essentially one used as a silicate or germanate in their ortho- or meta-form layer. One can also use a connection in which the storage electrode for television pick-up tubes

Applicant:

Robert Bosch G. m. B. H.,

Stuttgart 1, Breitscheidstr. 4th

Named as inventor:

Dr. Werner Tretner, Darmstadt

Lithium is in a stoichiometric excess, as is the case with water glass. By using a such a layer on the positively charged side of the glass film is achieved that during operation From the supply of the applied layer, easily mobile ions penetrate into the glass and at least partially replace the migrating sodium ions. Practical tests have shown that that in the case of an image plate treated in this way, afterimages only occur at significantly higher light intensities occur than before and the service life of the tube can be extended considerably.

The drawing shows a superorthicon tube which has a storage electrode in a piston 1 2 contains, which is slower with an electron beam emanating from a hot cathode 4 Speed is sampled.

The photoelectrons released at the photocathode 3 release secondary electrons at the storage electrode 2 which are picked up by the mesh electrode 5. Therefore, the photocathode charges 3 facing side of the film 2 positive compared to that scanned by the slow electron beam Side up.

According to the invention, this positively charged side is provided with a thin layer 6 made of lithium silicate or lithium germanate, which releases lithium ions relatively easily. The layer 6 can e.g. B. by Evaporation of the lithium compound can be made from a crucible.

Claims (2)

Patent claims: 1. Storage electrode for television pick-up tubes made of glass or a vitreous material which an alkaline, especially lithium-containing 409 588/167 3 4 Layer is applied, characterized in that lithium in excess indicates that the lithium compound is at hand. essentially a silicate or metasilicate and / 3. storage electrode according to claim 1 or 2, or Germanat is. characterized in that the applied 2. Storage electrode according to claim 1, characterized in 5. Layer is 300 to 500 A thick. 1 sheet of drawings 409 »8/167 4.64 ® Bundesdruckerei Berlin