JPS5842581B2 - cathode ray tube - Google Patents

Description

[Detailed description of the invention] This invention relates to a cathode ray tube.

More particularly, the invention relates to a cathode ray tube of the type which allows two information contents to be displayed simultaneously in different colors and with different persistence.To achieve this object, the structure proposed by the invention is described. Previously, an example of the application of this type of tube to a PPI-type radar that utilizes the simultaneous display of complex information content emitted from outside the radar was described.
The information is collected by the radar itself without any possibility of confusion between one and the other type of information.

In general, for this purpose, types of phosphors whose emissive layers have different residual properties and different spectra,
i.e. a type of phosphor that generates optical sweep lines with different colors and different extinction times at the location of electron impact, and which can be controlled by an accelerating voltage applied to the electrons in particular in these phosphors. A cathode ray tube with a screen made of phosphor with a decay time is used.

This type of screen is known from the prior art, particularly in British Patent Specification No. 1.
No. 303,749.

As explained in the above-mentioned patent specification, two types of phosphors (one with virtually no residual properties and the other with residual properties of a substantial degree, e.g. a few seconds, but with a barrier layer) are used. By forming the emissive layer of the screen with a mixture of (i.e., protected by a non-emissive layer under the action of bombardment), a simple variation of the accelerating voltage applied to the electrons can cause substantial A degree of persistence that can vary from a value of zero can be achieved.

Furthermore, if the two types of phosphors have different spectra, the colors of the two light sweep lines will be different from each other.

If the accelerating voltage is low, the resulting sweep lines in the color of phosphors of the type without residual properties are the only ones excited at the above voltage; A type of phosphorescent material with a characteristic color.

Thus, using a screen of the kind known from the technology described in the above-mentioned patent specification, the problem mentioned above, namely the problem of two-color display, is solved, while this is the problem that this invention seeks to solve. .

From the above, it is sufficient to vary the voltage applied to the tube in order to obtain the desired two-color display.

It is believed that by periodically switching the voltage between two values, a low value and a high value, it is possible to obtain the desired different colors and persistence.

However, in practice, this problem is not adequately solved when certain other specific conditions are imposed, as for example in the cited example, namely in the case of PPI radar screens which simultaneously display different information contents on the same screen.

In order to provide a more concrete idea of what is encompassed here, the relevant conditions will be discussed with respect to the examples discussed above.

The screen of a cathode ray tube contains information coming from the radar, in other words actual video information, and composite video information coming from external sources.
Two information contents are provided: information consisting of beacons, vectors, etc.

These two types of information are recorded in the tube in the form of swept lines of light produced by the impact of electrons forming part of the beam from the cathode ray tube's electron gun on the screen.

The radar screen operates, for example, in PPI mode (Planar Position Indication Mode) with the following characteristics:

Scanning time for each radius section of one complete rotation hexagram in a certain number of seconds, say 5 seconds, and □ in 1 second.

The radar emits a pulse of lμS duration every millisecond.

As for the external information, this is displayed on the screen of the tube according to a back-scanning action, i.e. the well-known random scanning, and for said scanning, for example, at a frequency of 50 Hz, i.e. at the rate of one complete scan of the screen every 20 milliseconds. It is enough to say what is done.

The frequency is high enough to give the impression of a flicker-free signal.

This is the case if a low voltage pulse is applied to the beam for a fraction of the above time of 20 milliseconds, for example at a low voltage of 10 kilovolts.

This voltage is simply the potential at the anode of the cathode ray tube or the conductive layer of the luminescent screen, and the potential at the cathode of the electron gun is taken as a reference.

During each of these pulses, the screen is fully scanned according to a random scanning action, which is repeated every second as already mentioned, and on the screen 0 there is a complex in the form of a light-sweeping line. Video information is recorded.

For this voltage value, the light sweep line on a screen with two types of phosphor, such as the prior art screen described in the above-mentioned patent specification, is different from that of the phosphor type without residual properties. It shows a color and this phosphor is the only one that is excited at that voltage.

The exact duration of these pulses is not specified as it is not really relevant to this invention.

The pulses are spaced apart by approximately 20 milliseconds, as discussed above, and the duration of each pulse is only a fraction of the 20 millisecond interval, as discussed above.

The high voltage, e.g. are formed on the screen and these remain indelibly on the screen for a few seconds after the electron bombardment, for example as mentioned above.

At this voltage, high voltage, the two types of phosphor components, those without residual properties and those with residual properties with a barrier, each have their own spectral color, e.g. In the case of green and those with residual properties, both are excited according to the orange color.

Therefore, in the PPI display, the viewer can see two consecutive sweep lines of green and orange.

Naturally, the ephemeral nature of phosphor types without residual properties of virtually zero persistence means that this sweeping line is not actually seen or perceived by the observer's eye. It is conceivable that this means that all that is the approximate average value between the color of the sweep line with the residual feature and the color of the sweep line without the residual feature.

This situation is actually quite different for reasons related to the substrate properties of the phosphor, which reasons are explained in detail below.

That is, when a cathodoluminescent material, such as the type of phosphor in question here, that is, a material that can emit visible radiation under the action of electron bombardment, is bombarded by an electron beam at the impact location, the material emits a light spot of increasing brightness for a certain period of time.

This increase in brightness is faster the less the material has residual properties, and is incomparably faster in the case of a material without residual properties than in the case of a material with residual properties.

This is why even short-lived swept lines with no residual properties are perceived by the observer's eye, and the very high brightness, which reaches extremely quickly during the electron bombardment time, has residual properties despite its short duration. The short-lived sweep line mentioned above is given the upper hand through the sweep line with

Therefore, true video information (PPI) and composite video information can actually be displayed using screens with two different types of phosphor as described in the prior art mentioned above, and The phosphors produce different colors by appropriate selection of the spectra of the two phosphors.

That is, even if the sweeping line corresponding to the true video information exhibits the same color as the composite video information at the instant of its appearance on the screen and for a short time thereafter, the PPI
Each orange sweep line corresponding to the scanning action is preceded by a kind of green flash.

This is more commonly referred to as the "flash" phenomenon.

The existence of this kind of flashlight is observed because it is not due to the confusion that occurs between the sweep lines corresponding to the two scanning actions, but because of the rapid change between the perception of two different colors faced by the observer. This is extremely undesirable from a person's point of view.

The object of the invention is to provide a cathode ray tube that does not have this drawback.

This is accomplished by using a third phosphor to form the luminescent layer of these cathode ray tube screens, as described in detail below.

In order to achieve this result, the luminescent layer of the cathode ray tube screen is composed of three types of phosphors with different spectra, two of which have barriers as described above, This is done under the conditions set out below with reference to the accompanying drawings.

In addition to the two components 1, 2 of the prior art screen described in the above-mentioned patent specification, a third element 3 is provided in the case of the screen according to the invention.

In the drawings, reference numerals 1 and 2 represent, respectively, a type of phosphor having substantially no residual properties and a phosphor with residual properties, and reference B indicates a type of phosphor which is combined with a phosphor having residual properties and is It shows the barrier defined in the above-mentioned patent specification, with respect to which, as is known from the above-mentioned patent specification, it plays an essential part in the generation of the variable residual characteristic effect.

To summarize this part here, under the electron bombardment of the electron beam, the applied voltage to the electron beam is a given value V for operation according to FIG. 3 due to the barrier B (shaded area).

If the voltage applied to the electrons exceeds the above-mentioned value, then an optical sweep line is generated in the phosphor 2, which has a residual characteristic only when the electrons reach the phosphor 2. can only completely cross the barrier B above.

Voltage V is value V. When the voltage rises to above, a residual characteristic whose duration changes according to the voltage V is obtained by the relative arrangement of the straight lines r and nr1, and these straight lines r and nrl each have a residual characteristic and the phosphor 2 button and the residual characteristic. The brightness of the beam sweep line at the phosphor 1 is shown as a function of the voltage V, and this arrangement also has a residual characteristic that increases the overall brightness of the sweep line appearing at the point of impact of the beam on the screen by the phosphor. A portion is made to vary according to the voltage.

In the cathode ray tube screen according to the invention, the luminescent layer is of a type having substantially no residual properties in combination with the barrier B, as in the case of the phosphor 2, as shown in FIGS. It has a third component 3 consisting of a phosphor.

The straight line nr3 represents the brightness of said third phosphor with barrier in the diagram of FIG. 3.4.

As a schematic example, the drawing shows three components of the luminescent layer C of the screen (the substrate is designated S) juxtaposed, with a barrier B on the side of the entrance of the electron beam, indicated by the arrow F. is superimposed on the phosphor of its associated type.

This means that all possible structural buttons and especially phosphor components consistent with the technology of these screens are mixed with each other and that the types of phosphors with barriers are in this case completely covered with their barriers. This is a schematic example for easy understanding and inclusion of covered structures.

All these mutually equivalent structures can be considered to be represented by the schematic structures shown in FIGS.

This is V in the case shown in the example of FIG.

This is the case when lower voltages are applied to the beam, i.e. when a random scanning operation corresponding to composite video information is carried out, and only the phosphor 1, which has no residual properties, is present in the beam, e.g. as previously assumed. emits a green ray.

If a high voltage greater than or equal to Vo is applied to the beam during PPI scanning of real video information (Vo is a barrier combined with a phosphor 3 that has no residual properties, as in the example of FIGS. 1 and 3), (the voltage is just sufficient to pass the electrons through the whole of B), a swept line of color corresponding to the phosphor 3 appears on the screen, indicating that the phosphor excited at this voltage Superimposed on the color generated by light body 1.

Therefore, at this voltage, the flash has a color as a result of the superposition of the previous green color and the color of the phosphor 3, which has no residual properties.

In the examples shown in FIGS. 1 and 3, the voltage is V. The light rays produced by the phosphor 2 with a residual characteristic appearing at are the color of the phosphor 2 with a residual characteristic, i.e., orange, as assumed earlier.

Spectrum of phosphor 3 and phosphor 1, 2
．． By appropriately selecting the conditions for mixing (3), the cathode ray tube of the present invention produces "flashlight" whose color depends on the residual characteristics of the phosphor 2 due to the spectral overlap of the phosphors 1 and 3. The phosphor 3 is selected to generate a red light sweep line, ie considering the green and orange colors mentioned above.

Thus, undesirable flashlight effects during PPI scanning are eliminated.

It should of course be noted that the selection of the phosphor 3 and its combined barrier for a given type of phosphor 1, 2 (and combined barrier) requires a number of conditions.

First of all, as already mentioned, the spectrum of phosphor 3 is such that the spectra of phosphors 1 and 3 overlap, resulting in approximately the same color as that produced according to the spectrum of phosphor 2. You need to choose.

However, regarding the selection of these spectra,
Laws regulating the "rise" characteristic of each of the 1.30 phosphors, i.e. the rise in brightness of the light sweep line that appears for each of these phosphors at the time of electron bombardment, starting from the instant at which the electron bombardment takes place. It is also necessary to consider

For example, in the case of phosphors that do not have two residual characteristics, such as phosphors 1 and 3, these extremely steep rises do not necessarily follow the same law as mentioned earlier. Rather, the laws relate to the properties of each type of phosphor.

Furthermore, the time to maintain these brightnesses must be taken into account, and these times are very short in the case of phosphor types without residual properties, but are not strictly zero and may also be It does not necessarily have to be the same for the two types of phosphors.

These two considerations are limiting regarding the flash color button and its intensity.

Given low voltage V.

, the value of the high operating voltage v1 (FIG. 3) also acts, which increases the brightness Ll, L2 of the swept lines generated by the three phosphors as shown in the diagram of FIG. t
Corresponds to L3.

Similarly, the thickness of the barrier in combination with the various phosphors 2, 3 must play an important role, and these barriers, generally of the same material, are shown in the drawing in the shaded area B.
are uniformly shown.

A wide variety of these materials are known in the luminescent screen art.

If the barrier thicknesses are different, the operation follows the diagram of FIG.

This diagram is the same as the diagram in Figure 3, Vol.

Vo2 is the value of the voltage V, and above this value, the phosphor trigrams and the phosphor 2 are excited, respectively.

Furthermore, in this case, at the voltage V between 1 e Vo□O,
A color intermediate between the colors of the sweep lines of phosphors 1°3 of the type without residual properties, i.e. in the case of the colors cited in the previous example a yellow sweep line without residual properties is obtained. .

v2 is the high operating voltage. Finally, of course, the 1, 2, 30 proportion of the various phosphors in the luminescent layer C plays an important role.

All these parameters are limiting with respect to the final result.

FIG. 2 shows another embodiment of the invention, in which a phosphor 1 without residual properties is combined with a phosphor 3 without residual properties and a barrier B with a phosphor 3. cover.

In this embodiment, the phosphor 1, which has no residual properties, acts to some extent as a barrier to the phosphor.

In one example, a mixture of red and green phosphor powders with no residual properties is formed, both of which are phosphor powders in an "E 1ectron tubeConn".
A third powder, an orange phosphor with residual properties, is listed in the above publication, Jedec P, 22; all these powders are listed in the above publication, 26. It has a particle size of ~20μ.

Two types of phosphor without residual properties were used in a proportion of 20-30% by weight in the mixture.

The powder of red phosphor 3, which had no residual properties, was coated with a barrier layer of non-luminescent material about 1 micron thick, similar to the powder of phosphor 2, which had residual properties.

No such barrier was provided for the green phosphor.

The screen was operated with a beam current of 10.18 kilovolts and over 500 microamps.

The invention is not limited to the above-mentioned applications mentioned merely as examples.

[Brief explanation of drawings]

1 and 2 show two embodiments of the luminescent layer used in the screen according to the invention, and FIGS. 3 and 4 are diagrams corresponding to two cases of the operation of the screen according to the invention. In the drawing, 1 is a phosphor without residual properties, 2 is a phosphor with residual properties, 3 is a third phosphor without residual properties, B is a barrier, and C is a phosphor with residual properties. It's basic.

Claims (1)

[Claims] 1. The luminescent coating comprises a screen consisting of two types of phosphor, one of the phosphors is non-persistent;
On this one phosphor, the electron beam generates at its impact location a four-point spectral optical sweep line that actually disappears as soon as this impact occurs, and the other phosphor has a persistence on this other phosphor with a spectrum different from that of the light swept line, and the other phosphor is visible for a period of time after the impact; With an inert barrier that does not produce an optical sweep line under the action of a shock, the voltage accelerating the electrons of the beam is sufficient to force the electrons to pass through the barrier and excite the brightness in the persistent phosphor. In a cathode ray tube in which the screen produces a sustained light sweep line when the voltage is above the above value and a non-sustained light sweep line for any voltage below the above value, the cladding further comprises a barrier. said barrier is formed such that said third phosphor is excited when the voltage exceeds said value, and said barrier is formed such that said third phosphor is excited when said voltage exceeds said value; The spectrum of the third phosphor superimposed on the spectrum of the body produces a color approximately the same as that of the persistent phosphor, and when the voltage exceeds the above value two non-persistent phosphors appear. The light sweep line appearing on the screen at the point of impact of the beam by the light body exhibits approximately the same color as the color caused by the persistent phosphor, and a flash of a different color appears before the appearance of the persistent light sweep line on the screen. A cathode ray tube characterized by avoiding the flashing effect that appears in