RU2322728C1 - Cathodic fluorescent screen - Google Patents

Abstract

FIELD: electronics; displays, television sets, matrix panels and screens for displaying visual information in various individual and shared apparatuses.

SUBSTANCE: proposed cathodic fluorescent screen incorporating transparent vacuum shell with front panel and board carrying anode electrodes covered with at least similarly colored phosphor, control electrodes, and wire cathodes secured by means of holders within vacuum shell orthogonally to anode electrodes connected to current-carrying tracks with external leads has its wire-wound cathode holders made in the form of flat linear springs parallel to anode board surface; holders are disposed beyond information field of anode board and mounted at minimal distance from anode and from one another; wire cathodes are made in the form of film-coated metal threads tightened on holders for hot or cold emission of electrons; control electrodes are disposed on face plate in the form of narrow film strips parallel to wire cathodes.

EFFECT: improved ergonomic characteristics, enhanced reliability and displayed information quality.

1 cl, 4 dwg

Description

The invention relates to electronics, in particular to screen displays, and can be used in the development of television receivers, matrix panels and screens for displaying visual information in various devices for individual and collective use.

The design of most cathodoluminescent screens is adapted to read information “on reflection, i.e. viewing the image from the same side from which bombarding electrons fall onto the surface of the luminescent screen. This is due to the fact that the brightness of the glow of the screens for reflection is much higher than for lumen. In addition, reflection screens are less critical to the thickness and structure of the luminescent layer.

Obviously, the internal armature of the screen through which information is read should not impede observation. To reduce interference, very thin (up to 7–10 μm) oxide cathodes are used. Their temperature does not exceed 700 ° C, and, therefore, the intrinsic radiation is negligible. Control grids, as a rule, are made by photochemical milling. They have a fine structure and high transparency. Auxiliary structural elements (cathode holders, contact springs, getters, etc.) are carried out as far as possible outside the information field of the screen. If necessary, parts of internal fittings are matted or blackened (see B.I. Gorfinkel, B.V. Abalduev, R. S. Medvedev, A. P. Loginov “Low-voltage cathodoluminescent indicators”, Moscow, “Radio and communication”, 1983 g., pp. 30-35).

Important elements of the vacuum luminescent indicator device that significantly affect the ergonomic characteristics of the device and the complexity of its manufacture are conductive wiring, numerous metal leads (such as a comb) and the base of the segments with a luminescent layer forming an indication pattern, contact pads for mounting cathode-grid fittings, getters etc., which are subject to requirements such as low electrical resistance, lack of wiring gloss, making reading difficult information, ensuring the reliability of the adhesion of the cathodoluminophore layer, the absence of diffusion of toxic impurities in the phosphors (see B. L. Lisitsyn “Display Elements”, M .: Energia, 1978, p. 60).

The disadvantage of this design is that it requires complex technology and the high complexity of manufacturing the anode plate, internal cathode-grid fittings and metal leads.

The closest analogue in technical essence to the proposed solution - the prototype is the design of a multi-color cathodoluminescent screen matrix type described in patent RU No. 2137246, MKI ⁶ : H01J 31/12, 31/20, publ. 08/27/2001, containing a vacuum shell, a system of directly heated cathodes, rows of anode electrodes deposited on an insulating base, coated with a phosphor and connected by current-carrying paths with external leads through contact pads, inside the vacuum shell are direct-heating cathodes and control electrodes orthogonal to the anode electrodes and forming light emitting segments.

In the manufacture of the screen, all direct-heating cathodes should be in the same plane and at the same distance from the anode plate and from each other. In addition, the distances between all elements may be small. In real devices, it is quite difficult to achieve the exact arrangement of filaments of directly heated cathodes. The distance between the straight filament cathodes and anodes cannot be provided less than 1 - 1.5 mm. All this leads to a deterioration in ergonomic parameters - a relative decrease in brightness, a deterioration in its uniformity over the field of the anode plate and an increase in supply voltage.

These drawbacks depend on how the cathode mount assembly is made, which fully determines its location.

The invention consists in the following. The problem to which this invention is directed is to improve the ergonomic parameters of the cathodoluminescent screen: increasing the brightness and uniformity of the glow, increasing the reliability of the cathodoluminescent screen and the quality of the information displayed.

These technical results during the implementation of the invention are achieved by the fact that in the cathodoluminescent screen containing a transparent vacuum shell, consisting of a face plate and a plate with anode electrodes located on it, coated with a phosphor of at least one color, control electrodes and wire cathodes fixed by holders inside the vacuum shell orthogonally to the anode electrodes connected to current-carrying tracks with external leads, the holders of the wire cathodes are made in the form of flat linear springs parallel to the surface of the anode plate, while the holders are located outside the information field of the anode plate and are fixed at a minimum distance from the anode plate and between each other, and the wire cathodes are made in the form of metal threads stretched on holders with a film coating for “hot” or “ cold "emission of electrons, the control electrodes are located on the front plate in the form of narrow film strips parallel to the wire cathodes.

The invention is illustrated by graphic materials, a description and an example of a specific implementation.

Figure 1 shows a General view of the cathodoluminescent screen.

Figure 2 shows a fragment of a cathodoluminescent screen with holders of wire cathodes.

Figure 3 shows the options for winding the cathodes on the holders: a) in the form of a single thread; b) in the form of a spiral.

In the drawings, the following notation:

1 - cathodoluminescent screen;

2 - a vacuum shell;

3 - front plate;

4 - board;

5 - anode electrodes;

6 - phosphor;

7 - wire cathodes;

8 - control electrodes;

9 - holders for wire cathodes;

10 - current-carrying tracks;

11 - conclusions.

The cathodoluminescent screen 1 contains a vacuum shell 2 consisting of a face plate 3 and a board 4. On the board 4 there are anode electrodes 5 coated with a phosphor 6 of at least one color. Inside the vacuum sheath 2 there are wire cathodes 7 and control electrodes 8 orthogonally to the anode electrodes 5 connected by current-carrying paths 10 to external leads 11. The holders 9 are made of spring material, for example, foil, for the wire cathodes 7, while the holders 9 are located on the periphery of the anode boards 5 are outside the information field, and are rigidly fixed at a minimum distance from the anode board and between each other.

The cathodoluminescent screen operates as follows.

Obtaining a luminescent image on the screen is achieved by the method of matrix formation from separate luminous points, each of which is obtained at the intersection of the control electrodes 8 and the anode electrodes 5, which are currently simultaneously fed a positive potential. To stop the glow on the control electrode 8 is fed a negative potential.

Additionally made holders 9 for the wire cathodes 7, while the holders are located on the periphery of the board 4 of spring material, such as foil.

The new holder 9 of wire cathodes 7 allows you to maximally approximate wire cathodes 7 to anode electrodes 5 ~ 0.2 mm ÷ 0.5 mm (instead of 1 ÷ 1.5 mm) and have a minimum distance between wire cathodes 5 of at least 1 mm (standard 2 5 mm).

The use of a new, more technologically advanced cathode assembly in the cathodoluminescent screen with a smaller cathode pitch (1.5 mm or less) or with a cathode pitch that matches the row pitch, in the case of using the “XY” matrix, with a shorter cathode-anode distance of 0.3 mm makes it possible to obtain a new, simplified screen design with its reduced cost and improved characteristics, i.e. increased brightness of the luminescence, with a lower supply and control voltage, improved uniformity of luminescence, transfer from a triode mode to a simpler diode power and control mode with the exception of control grids, use of low-voltage drivers to control the screen with the exception of numerous metal outputs of the "goose" type, as well elimination of glass racks and reduction of the gap between the glass panes (up to 0.5 ÷ 1.0 mm), which, in turn, virtually eliminates the explosion hazard of the device.

The cathode assembly consists of parallel tensioned strings made by winding a continuous oxidized tungsten wire (d = 0.009 mm ÷ 0.030 mm, where d is the diameter of the wire), fixed by pressing in spring (at least on one side) holders of wire cathodes with possible exception low-tech welding. Spring holders, in turn, are flat zigzag ribbons made of springy sheet material, for example, art. 12 × 1vn10 t S≈0.07 ÷ 0.2 mm (where S is the thickness of the sheet material) by photochemical group milling and fixed to the terminals of the screen glow. In this case, the necessary tensile force F _{tension of the} extended spring per one cathode for tungsten wire can be calculated by the formula:

where F _nat is the tension force in grams of one cathode at t = 20 ° C;

d is the core diameter of the cathode in microns.

The breaking strength of the tungsten cathode F _times at a temperature of t = 20 ° C can be calculated by the formula:

and stretching the length D _tensile springs within their elastic deformation, at t = 20 ° C should be not less than 7 ÷ 10 times the value of the linear temperature elongation (during heating of the cathode of 20 ° C to 700 ° C) of a particular cathode in the device because during the screen heat treatment, the elastic properties of the springs are weakened by at least 2 times, i.e.

where K.L.T.U. - coefficient of specific linear temperature elongation for tungsten,

Δt is the temperature difference during heating of the cathode in ° C;

L is the length of the cathode;

D _rast - the length of the tension of the spring within the elastic deformation at t = 20 ° C;

K is the coefficient of proportionality for the material of the springs St12 × 18n10 t, with 7≤K≤10.

Introduction of the proposed holders for direct cathodes makes it possible to obtain new positive characteristics for the cathode assembly, i.e.

1) manufacturability and ease of manufacture of holders;

2) the absence of problematic welding of wire cathodes on holders;

3) the exact positioning of the wire cathodes in height relative to the anode plate and step;

4) the exact, identical and reproducible tension of the wire cathodes, the absence of sagging and breaks in finished devices;

5) the possibility of winding fastening, electrical contacting the wire cathodes in the holders directly from the coil without reinforcing them;

6) the ability to mechanize the manufacture of cathode nodes by winding in a simple way;

7) the ability to arrange wire cathodes at a minimum height from the anodes (from 200 microns);

8) the ability to produce cathode nodes with a minimum step (from 1.5 or less);

9) the ability to exclude stamping holders;

10) the possibility of manufacturing simultaneously a large number of holders in a group method of photochemical milling with the saving of chemical solutions and materials;

11) the ability to reduce the amplitude of spurious resonant oscillations of the wire cathodes, as the proposed holders additionally have the property of spurious oscillation dampers (several tens of times in vacuum);

12) the possibility of winding wire cathodes with a small preliminary tension and then tensioning them directly in the device;

13) the possibility of increasing labor productivity in the manufacture of cathode nodes;

14) the possibility of eliminating "cathodic striping" due to the reduced pitch of the wire cathodes, eliminating the use of stretching scattering labor-intensive grids (diode power supply) with a simultaneous increase in brightness and a decrease in supply voltage.

The law of degree 3/2 of the dependence of the anode current on the cathode-anode distance (see Tsarev B.M. Calculation and design of electron tubes, Gosenergoizdat, M.-L., 1961 - textbook), which means the possibility of using relatively cheap low-voltage controllers drivers.

In addition, the use of the proposed cathode assembly in a cathodoluminescent screen creates additional advantages for the entire screen, i.e. the exclusion of racks that define the gap (~ 2.5 mm to 0.6 mm) between the anode plate and the face plate of the vacuum shell of the cathode-luminescent screen, virtually eliminates the explosion hazard of the device, and also allows you to additionally control the anode electrodes directly from the transparent face plate of the device (oxide bus Germany) without the use of control grids.

The introduction of holders for wire cathodes allows:

- reduce the voltage of the control electrodes and anode electrodes;

- apply low-voltage integrated circuits made with a large number of conclusions, which, in turn, will reduce the level of multiplexing of control signals, and this in turn will reduce the control voltage;

- increase the brightness of the cathodoluminescent screen;

- increase the service life of the cathodoluminescent screen;

- to simplify the design and manufacturing technology of the cathodoluminescent screen;

- reduce the cost of cathodoluminescent screens through the use of low-voltage cheap integrated circuits.

Claims (1)

A cathodoluminescent screen containing a transparent vacuum shell, consisting of a face plate and a circuit board with anode electrodes located on it, coated with a phosphor of at least one color, control electrodes and wire cathodes, fixed by holders inside the vacuum shell orthogonally to the anode electrodes connected to current-carrying tracks with external leads, characterized in that the holders of the wire cathodes are made in the form of flat linear springs parallel to the surface of the anode plate, while the holders are located outside the information field of the anode plate and are fixed at a minimum distance from the anode plate and between each other, and the wire cathodes are made in the form of metal filaments stretched on the holders with a film coating for “hot” or “cold” emission of electrons, the control electrodes are located on the front plate in the form of narrow film strips parallel to the wire cathodes.

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