SU1478262A1 - Light-protective screen for cathode-ray tube - Google Patents

Abstract

The invention relates to the field of information technology and can be used to protect the display elements designed to work in conditions of external illumination of varying intensity. The purpose of the invention is to expand the scope of the protective screen by increasing the viewing angle and contrast. This goal is achieved by the fact that in a protective screen 2 for a cathode ray tube 1 containing a base, this base is made in the form of slots 4, a reflective coating 6 is applied to the inner surface of the gaps 3 between the slots, and the total area of the holes is applied to the outer surface does not exceed half the screen area, the width of the gaps does not exceed the height of the cover. 1 il.

Description

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The invention relates to the information technology and can be used to protect the display elements intended to operate in external conditions of varying intensity.

The goal of the isobtopen is to expand the field of application of the light-emitting-screen screen to increase the viewing angle and contrast.

The drawing shows a light shielding screen for pshu-beam tube.

Electron1 o-lugPV1I tube 1 has a light-proof ecoan 2 in the form of a lid, at the bottom of which there are gaps 3, with slots D, a heat-absorbing coating 5 "photoelectric coating 6.

The screen is as follows.

A flux stimulates the illumination of the optic op egg of the pento-ray tube., KOCH-ORG-G, delivers visible light that transmits to the normal signal (which is determined by the spectral characteristics of the phosphor or optical filter). The rays are emitted partially immediately through the speech 4 partially after a series of reflections between the porosity of the screen and the surface of the phosphor itself facing it. Light from external sources is absorbed mainly by the black surface of ecoan 2, it only partially penetrates through slots 4 into the cavity between the phosphor and the screen, and then is emitted through the same slots. In the ideal case (when the screen forms a closed absolutely reflecting cavity with an n-mino- phoric layer, n „p, е 1), the loss of the useful. radiation is zero.

The absorption of the useful radiation is (1 lЈ) 100%, and the illumination of the HUNDRED is -co) + (1 -2) p "" 100%, where Ј is the utilization factor of the luminous flux of the phosphor. The value can be calculated as the sum of an infinitely decreasing geometric progression with a coefficient (1 - -SE) pp pz every i-th member of which.

(the first of them is equal to oz) is the fraction of the luminous flux of the phosphor passing through the slots into the observation space after (i-1) pairs of reflections from the screen and the phosphor. This amount

Q is approximately equal (exactly equal to a, d - Ј h «D

five

0

ha

1 - (1 -w) pnp,;

where р „tre is the reflecting ability of the phosphor-electron-tube and coating 6 of the fire shield, respectively, 1 is the absorbing power

cover 5 of screen1, - the ratio of the total area of the slots 4 to the total area of the inner-, surface of the screen,

a, d - the width of the slots and gaps; cooTBeTCTBeHHoJ h - the height of the cover; D is the diameter of the cap. The proposed screen allows to increase the viewing angle up to 180 °.

Claims (1)

Invention Formula A light shield for an electron beam tube containing a base, characterized in that, in order to expand the scope of a light shield by increasing the viewing angle, the base is made in the form of a lid, at the bottom of which slots are made, on the inner surface of the gaps a reflective coating is applied between the slots, and an absorbing 5 absorbing coating is applied to the outer, while the width of the spaces between the slots does not exceed the height of the cover.