JPS59105247A - Cathode-ray tube - Google Patents

Abstract

PURPOSE:To obtain a CRT with which a light pen can be used by using for the phorphor screen a phophor in which the ripple ratio obtained by subjecting persistance waveform to Fourier series development is below 1.0% and which has a 10% persistence time of below 10 miliseconds. CONSTITUTION:In a display CRT, at least one phosphor in which the ratio of the first term to the tenth term obtained by subjecting persistence waveform to Fourier series development in the field and ndicating the ripple ratio is below 1.0 and which indicates a 10% persistence time of below 10 miliseconds, is used for a phosphor screen. As a result, effective flicker-alleviating effect is obtained. Besides, owing to pulses of low luminous efficiency and the short persistence component which have almost no influence on the luminous color, the luminance and the flicker characteristics of the entire cathode-ray tube, a light pen can be used with the cathode-ray tube.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to cathode ray tubes, and more particularly to a phosphor for forming a phosphor screen suitable for cathode ray tubes for displays that enable the use of light beams.

[Technical background of the invention and its problems]

A cathode ray tube having a phosphor screen made of a flicker-free phosphor with little flicker (7 flickers) has been put into practical use as a computer terminal display device that can withstand use at low vertical frequencies and multiple scans.

As this 7-litre power-less phosphor, the emission intensity is 1/1
It is common to use a long afterglow phosphor that takes several tens of seconds or more to reach 0 K (10% afterglow time).

However, with such a phosphor, the curve (1
) from the excitation point (2) to the vertical field time (T)
(T mini 5 to 25 milliseconds) After that, it shows a gradual decay characteristic until it is re-excited, so it is not possible to give the light ben a sharp pulse with a narrow time width that is sufficient to indicate the screen position. There is a problem that Lightben cannot be used.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a cathode ray tube for a display having a flicker-free phosphor screen that can be used with light bulbs that overcome the above-mentioned problems.

[Summary of the invention]

That is, the present invention shows the ripple ratio when the afterglow waveform is expanded into a Fourier series within the field. This is a negative full-ray tube characterized by using at least one of the following phosphors in the phosphor screen.

[Embodiments of the invention]

In general, long afterglow phosphors and flickerless phosphors are not equivalent.

That is, the afterglow waveform L (t) of the phosphor, where t is time, T is the vertical deflection (field) period Ln,
ψn is the expansion coefficient, and when the Fourier series is expanded in the field, the contrast ratio (ripple ratio) of the -th approximation waveform is ρ-=L, /Lo... (2) is the flicker
It is a physical quantity that represents the amount of reduction, and the lochi decay time has no direct relationship with the flicker reduction effect.The phosphor that forms the fluorescent screen of the cathode ray tube used in ordinary television picture tubes is 1/T with ρ = 2. = 6°Hz or less, flickering is felt, whereas at ρ;l, 1/T = 5
At 5Hz, p = 0.1, 1/'l'' = 40
There is no flicker even at Hz. That is, it can be said that a material with ρ of 1 or less is a flickerless phosphor having an effective flicker reduction effect.

Now, the vertical field time (T) from the excitation point α (T'E: 15~2
Considering a phosphor whose decay characteristic shows a rapid decay immediately after the excitation point dries up until it is re-excited after 5 milliseconds, the component that exhibits a rapid decay immediately after the excitation point aa is due to the light pen. The emission center may have any wavelength with high light-receiving sensitivity, and although the temporal peak value intensity is high, the time width is narrow, so the emission efficiency is very low. On the other hand, the component 51) Q3, which exhibits a gradual attenuation in the latter half of the field, exhibits a display color and has a low temporal peak intensity but a long luminescence time, so it emits less light than the short afterglow component. High brightness. If the approximate curve (14) of the Fourier first-order term of the afterglow waveform of the phosphor having multiple emission centers shows a gentle amplitude as shown in the figure,
If the ripple ratio is 1 or less, it shows an effective flicker reduction effect, and moreover, it has a low luminous efficiency and a short afterglow component that has little effect on the overall luminous color, brightness, and flicker characteristics. It becomes possible to use it.

〔Effect of the invention〕

As mentioned above, if the ratio of the 1st order term to the 0th order term, which indicates the ripple ratio when the afterglow waveform is expanded into a 7-lier series within the field, is 1.0 or less, then pl is the 10% afterglow time. By using at least one phosphor with a luminance of less than 10 milliseconds in the phosphor screen, a cathode ray tube for displays that can be used with 9 light rays can be obtained, so its industrial value is great.

[Brief explanation of drawings]

Figure 1 is a graph showing the afterglow waveform of a conventional long afterglow phosphor.
FIG. 2 is a graph showing the afterglow waveform of the flickerless phosphor applied to the cathode ray tube of the present invention. 1.11...Afterglow waveform, 2,12...Excitation point, 1
4...Approximate curve of Fourier first-order term. Agent Patent Attorney Inoue - Male Figure 1

Claims (1)

[Claims] The ratio of the first-order term to the zeroth-order term, which indicates the ripple ratio when the afterglow waveform is expanded into a 7-lier series in the field, is 1.0 or less, and the lO% afterglow time is 10 milliseconds or less. A cathode ray tube characterized in that at least one phosphor is used in the phosphor screen.