U.S. Philips Corporation

Derek Washington

Alan G Knapp

Hewson Nicholas King

Daphne L Lamport

Pieter Schagen

Alfred W Woodhead

John R Mansell

Pamela May Stubberfield

Roger Pook

Ronald W Gill

Willem M Van Alphen

Colin D Overall

Henry D Stone

Andrew J Guest

In order to reduce contrast degradation in an electrostatically scanned flat cathode ray tube having a channel plate electron multiplier, due to back-scattered electrons entering channels remote from their origin, a coating of a material having a low back-scatter coefficient is applied over the input of the electron multiplier between the apertures therein. The surface texture of the material should be microscopically rough. The material can be applied to the first dynode or to an electrode electrically and physically connected to the first dynode. The acceptance angle of the channel plate electron multiplier may also be restricted.

Cathode ray tube with means for preventing backscatter from electron

In order to reduce contrast degradation in an electrostatically scanned flat cathode ray tube having a channel plate electron multiplier due to back-scattered electrons entering channels remote from their origin, steps are taken to restrict the acceptance angle of the channel plate electron multiplier. In one arrangement means are provided on the input surface to restrict the angle of entry to a range normally associated with the addressing electron beam. In another arrangement the ready emission of secondary electrons is restricted to a predetermined arcuate portion of the input of each channel of the electron multiplier. In either arrangement stray electrons are unable to impinge upon the secondary emitting material in the channels and in consequence produce many fewer back-scattered electrons. Optionally a material having a low back-scatter coefficient and a microscopically rough surface texture may be applied to the exposed surfaces, apart from the apertures, of the input side of the electron multiplier to reduce the number of back-scattered electrons.

Cathode ray tube

In order to prevent the walls of the envelope (10) of a flat panel display tube having a large area screen from imploding, supporting walls (22) are provided to divide the interior of the envelope into a plurality of modules. Each module has its own electron beam generating means (24) for producing a low voltage, low current, intensity modulated electron beam (26) which is directed vertically upwards. A laminated channel plate electron multiplier (28) is disposed across the module and extends substantially parallel to the front and rear walls (12, 14) of the envelope. A single column of channels in the electron multiplier (28) is illustrated. The spacing of the channels determines the vertical resolution of the image produced. In order to deflect the electron beam (26) into a particular channel, a plurality of deflector electrodes (30) are disposed on the rear wall (14). These electrodes (30) and the input dynode of the electron multiplier (28) are generally held at the same potential to define a field-free space. However, in order to deflect the electron beam (26), the potential applied to electrodes (30) ahead of the deflection point is reduced so that the beam is deflected towards the selected channel in the electron multiplier (28). The current-multiplied electron beam from the output of the electron multiplier (28) undergoes focusing, horizontal deflection and post deflection acceleration as a result of suitable voltages applied to electrodes provided on the supporting walls (22). These electrodes may be parallel to each other or may diverge in a direction towards the front wall (12).

Display tube

In a flat cathode ray display tube of the type comprising an envelope having parallel front and rear walls and containing implosion-preventing support walls dividing the envelope into a plurality of modules, each module including a thermionic wire electron emitter, a switching electrode arrangement having a plurality of apertures to define one of a plurality of electron beam paths directed towards a cathodoluminescent screen carried on the front wall, and a channel electron multiplier intermediate the switching electrode arrangement and the screen for beam current multiplication, and electrodes carried by the support walls for line scanning and electron acceleration, the switching electrode arrangement comprises a stack of mutually insulated electrodes associated with each aperture and selectively operable to allow or prevent electrons to pass therethrough thereby to effect frame scanning.

Electrical interconnection between a leadthrough in a cathode ray tube envelope wall and terminals for internal, electrically operable, components such as an electron gun, is established by flexible conductor means comprising a flexible circuit consisting of one or more polyimide films with conductive tracks deposited thereon and, secured to the film(s) to form a single assembly, a further one or more superposed polyimide films having spaced apertures through which at least one conductor element, for example of metal wire or tape, is woven. The conductor element(s) can carry high currents safely and the conductor means is sufficiently thin and flexible to be routed round internal components easily.

Flat cathode ray tube having flexible, woven conductors

A channel plate electron multiplier is mounted parallel to, but spaced from, the screen. The electron multiplier comprises a stack of juxtaposed substantially planar apertured dynodes with the apertures therein aligned to form channels. An apertured extractor electrode is mounted on the output side of the electron multiplier. Preferably two or more foraminous deflector electrodes are mounted on the extractor electrode. The apertures in the foraminous deflector electrodes have the same pitch as the channels of the electron multiplier but are offset laterally relative to each other and to the axes of the channels by amounts which allow the emergent electron beam from each channel to pass through to the screen without impinging upon the deflector electrodes. By applying a potential difference between the deflector electrodes an electron beam emerging from its respective channel is deflected laterally onto a respective one of its associated group of phosphor stripes. The apertures in the deflector electrodes may be circular, elliptical or polygonal for example square, rectangular or hexagonal.

Color cathode ray tube including a channel plate electron multiplier

A penetron color display tube including a channel plate electron multiplier disposed between a low energy electron-beam-producing means and a luminescent screen. The screen is formed from repetitive groups of phosphor elements for luminescing in different colors. Each group includes a first phosphor element having a single layer of material for luminescing in a first color, such as blue, and a second phosphor element having two layers of material for luminescing in second and third colors, such as red and green. The channel plate electron multiplier includes a multiplicity of electron-multiplying channels for emitting individual electron beams when the low energy electron beam is directed into the channel's input. At the output of each channel is electrode means for selectively directing the emitted electron beam toward either the first or the second phosphor element in a group, and accelerating means for selectively accelerating the emitted electron beam to a predefined energy level to excite the selected layer in the group.

Penetron color display tube with channel plate electron multiplier

In a laminated channel plate electron multiplier, an apertured metal sheet (32) is disposed at a small distance (30 .mu.m) from the outer surface of the input dynode and is used to provide a small negative field for turning back stray secondary electrons which have sufficient energy to follow trajectories across the input side of the input dynode. More particularly, the areas between the apertures of the input dynode (22) are masked by a material (34) having a secondary electron emission coefficient of less than 2, which material (34) is provided on the outer surface of the apertured metal sheet (32), the metal sheet (32) being spaced from the input dynode (22) by an insulating material (36). A potential of the order of -10 V relative to the input dynode is applied to the apertured metal sheet (32).

Laminated channel plate electron multiplier

The image contrast in an image display tube having a channel plate electron multiplier (2) is improved by preventing secondary electrons emitted from the face of an input dynode (26) from straying to channels located at a relatively large distance from their origin. This is done by disposing a grid (24) at a short distance from the input dynode (26). If the grid (24) is held at a positive voltage relative to the input dynode (26), stray secondary electrons will be attracted toward the grid (24). Alternatively, if the grid (24) is held at a negative voltage relative to that of the input dynode (26), the secondary electrons will be induced to enter channels close to their origin.

Image display tube having a channel plate electron multiplier

A channel plate electron multiplier of the discrete dynode type formed from conductive sheets which are stacked in closely spaced relation. Each sheet is perforated with apertures which are aligned to form electron multiplying channels. The apertures in each sheet have input and output and cross sections which are approximately the same size and a concave shaped inner surface profile which causes a majority of electrons to strike the inner surface close to the output end, whereby the gain of the multiplier is increased.

Electron multipliers

In a channel plate electron multiplier having a stack of perforated conducting sheet dynodes insulated from one another, electrons incident on the input face of the stack which do not enter the channels give rise to unwanted secondary electrons which move transverse to the channels in the space in front of the stack. These secondary electrons enter channels remote from the point of incidence and thereby degrade the definition and contrast of an electron image transmitted by the channel plate. A layer of material having a low secondary electron emission, which may be on a sheet carrier, is provided on the stack input face.

Channel plate electron multiplier

Channel plate image intensifiers, for use as raster intensifiers in cathode ray tubes for example, comprise a stack of alternately arranged perforate laminar dynodes M and perforate laminar separators D aligned to form electron multiplier channels P. Each of the separators comprise a perforate aluminium plate having an anodized layer some 15 microns thick on the plate surface. Such separators can be manufactured to have the desired electrical characteristics and uniform thickness over their entire area so that the dynodes M are parallel to each other and provide a uniform gain over their entire area. The invention also relates to a method of anodizing perforate and imperforate aluminium foils.

Channel plate electron multipliers

A channel plate with color selection electrodes and color phosphors for use as an image display screen in a color television tube. This is a division, of application Ser. No. 288,597, filed Sept. 13, 1972, now U.S. Pat. No. 3,860,849, Jan. 14, 1975.

Channel plate with color selection electrodes and color phosphors

Electron beam apparatus comprising a channel plate which emits electrons in the form of hollow electron beams, a focusing control electrode for controlling the diameter of the hollow beams and a target having a pattern of concentric areas aligned with each hollow beam, said pattern having at least two different areas which respond differently to electron bombardment and may be selectively bombarded under control of said electrode.

Color tube having channel electron multiplier and screen pattern of

A channel plate with color selection electrodes and color phosphors for use an an image display screen in a color television tube.

Growing community of inventors

Wallington, United Kingdom

Derek Washington