JPS60264027A - Fluorescent character display tube - Google Patents

Abstract

PURPOSE:To perform blue luminous display while enabling to maintain its brightness for long hours by constituting a phosphor of ZnS:Ag and ZnO:Zn containing a pigment, while making the amount of ZnO:Zn to be specific weight % as against the whole amount of phosphor. CONSTITUTION:A ZnO:Zn phosphor, whereto 16.7wt% of cobalt aluminate as a pigment is added, is made and said phosphor is added to the phosphor made of ZnS:Ag+In2O3 while being kneaded for regulating the quality of phosphor paste. For securing here a practical life of more than 1,000hr and value more than 100fL of luminous brightness, the content of ZnO:Zn is required to exceed 20wt% of the whole weight of the phosphor. Next, for discerning blue of a luminous color, the relative intensity of a luminous specter as against the luminous spector of 450nm is required to exceed 50%, while accordingly requiring the content of ZnO:Zn mixed with the pigment not exceeding 75wt%. In this way, it is possible to perform blue luminous display while maintaining its brightness for long hours.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a fluorescent display tube for displaying blue light.

[Prior art]

Traditionally, fluorescent display tubes emitted only green light, but in recent years,
Improvements in phosphors have made it possible to obtain luminescent colors such as mu-red, evening, and monochrome, and they have come to be used in display devices for various types of equipment. These phosphors are made by mixing an appropriate amount of a conductive material such as indium oxide (inz03) with a sulfide-based phosphor for high-speed electron beams, and have been improved to be suitable for low-speed electron beams used in fluorescent display tubes. There is.

FIG. 1 is a sectional view showing the main parts of a fluorescent display tube constructed using this fluorescent material. In the figure, reference numeral 1 denotes an insulating substrate such as a glass substrate, on which a wiring conductor layer 2 is formed, and an anode conductor layer 4 is electrically connected through a through hole 3a of an insulating layer 3. On the anode conductor layer 4, a sulfide-based phosphor such as ZnS:Ag+InzO*, which emits blue light with a slow electron beam, is deposited by screen printing, and this phosphor forms the phosphor layer 5. are doing. A mesh-like control electrode 6 and a filament-like cathode 7 are arranged above the phosphor layer 5, and a front envelope 8 is arranged above them.

Supplying an anode voltage of about 15 volts to this fluorescent display tube,
When operated for a long time, as shown in FIG. 2, characteristics of luminance change and anode current change (both values relative to the initial value) with respect to the operating time are obtained. In FIG. 2, the curved line indicates the anode current, and the curved line indicates the luminescence brightness. FIG. 3 shows the characteristics of the anode current with respect to the filament voltage (cathode temperature), where the curve a represents the anode current immediately after the start of operation, and the curve a represents the anode current after long-time operation. In Figure 3, the broken line indicates the filament's rated voltage, and therefore, the intersections A and B between the broken line and curves a and b indicate the change in anode current before and after supplying the rated voltage to the filament and operating it for a long time. ing.

As shown in Figures 2 and 3, Z emits blue light.
The nS:Ag+In20g phosphor had the drawback that it was not practical because the anode current decreased significantly when operated for a long time, so the brightness was halved even within 1000 hours and the display quality was degraded.

ZnO:Zn, which has been used in the past and emits one color of green
This deterioration in display quality rarely occurs with phosphors, so in order to solve the above drawback, pigments such as cobalt aluminate and ultramarine are mixed with ZnO:Zn phosphors to change the luminescent color to blue. However, since the pigment itself does not contribute to luminescence at all, the obtained light output is dominated by the green luminescence of the ZnO:Zn phosphor, and the desired blue luminescence is hardly obtained.

[Object and structure of the invention]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a fluorescent display tube that can display blue light and maintain its brightness for a long time.

In order to achieve such an object, the present invention comprises a phosphor made of ZnO:Zn containing S:Ag and a pigment;
O: Zn is 20 to 75 percent by weight of the total weight of the phosphor.

The present invention will be described in detail below.

〔Example〕

The pigment cobal aluminate 1416.7i was added to create a ZnO:Zn phosphor.
S:Ag+In is added to a phosphor consisting of 2 or 3, and an appropriate amount of a vehicle consisting of an organic binder such as ethyl cellulose and an organic solvent is added and kneaded well to prepare a phosphor paste. This phosphor paste is made of pigment-containing ZnO:Z
Make various products with different amounts of phosphor.

Next, a phosphor layer 4 was formed by screen printing using these phosphor pastes, and phosphor display tubes were produced for each type having a different ZnO:Zn content.

When these fluorescent display tubes are operated by applying an anode voltage of about 15 volts, the luminance characteristics shown in FIG. 4 are obtained. From Figure 4, we have found that the brightness characteristics of the ziQ:Zn phosphor mixture, which is a mixture of pigments and pigments, increases as the amount of the Zn phosphor added increases. Table 1 shows the peak wavelength of the tube's emission spectrum.

Table 1 As can be seen from Table 1, as the content of ZnO:Zn containing pigment increases, the peak wavelength of the emission spectrum shifts from 450 nm, which is the peak wavelength of blue emission, and the cobalt aluminate mixed Z A characteristic is obtained in which light emission shifts to a peak wavelength of 496 nm, which is the emission color of the nO2Zn phosphor.

Next, the anode current density of these fluorescent display tubes was set to 3.3 m
Figure 5 shows the time required for the initial luminance to drop to half as A4. From this figure, pigment mixture Z
It can be seen that as the content of nO:Zn phosphor increases, the lifetime increases exponentially.

The following conclusion can be drawn from the above characteristics. Practical lifespan 10
In order to secure a luminance of 100 hours or more and a luminance of 100 (fL) or more, it is necessary to use Z n O mixed with a pigment.
From FIGS. 5 and 4, the content of Zn must be 20% by weight or more based on the total weight of the phosphor. Next, in order to distinguish whether the emitted light color is blue or not, the relative intensity of the emitted light spectrum with respect to the emitted light spectrum of 450 nm fi5
For this purpose, the content of ZnO:Zn mixed with the pigment must be 75% by weight or less.

The above examples are for ZnO:Zn phosphors.

16.7% by weight of pigment was mixed with ZnO2Zn, but if the mixing amount was less than 2% by weight with respect to ZnO2Zn, a good luminescent color could not be obtained, and if it was more than 25% by weight, the luminance of luminescence was significantly reduced. decreased. Furthermore, similar luminance and lifetime can be obtained by using ultramarine instead of cobalt aluminate as a blue pigment.

〔Effect of the invention〕

As explained above, this invention uses ZnS:Ag as a phosphor.
It is composed of +Inz03, ZnO:Zn, and a pigment, and the pigment and ZnO:Zn phosphor account for 20 to 75% by weight of the total weight of the phosphor, so blue light emission is obtained, and the brightness and lifespan are sufficient for practical use. This has the effect that a fluorescent display tube having the following properties can be constructed.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing the structure of a fluorescent display tube, Figure 2 is a graph showing changes in brightness and anode current with respect to operating time in a conventional blue-emitting fluorescent display tube, and Figure 3 is a cross-sectional view of a conventional blue-emitting fluorescent display tube. A graph showing changes in filament voltage and anode current in a light display tube. Figure 4 is a graph showing changes in luminance depending on the ratio of pigment mixed ZnO:Zn to the total weight of the phosphor. Figure 5 is a graph showing life. be. 1...Insulating substrate, 2...Wiring conductor layer, 3-9
- Absolute i1.3a - Bone - Through hole 4... Anode conductor layer, 5... Fluorescent layer. Patent Applicant: Ise Electronics Co., Ltd. Agent: Kazuya Yamakawa (12 persons) Fig. 1 Fig. 2 Operation 1 tone (6 years of darkness) Fig. 3 Filler/ant I voltage

Claims (1)

[Scope of Claims] 0) A fluorescent display tube that performs luminescent display by causing electrons emitted from the cathode to collide with a phosphor coated on the anode, in which the phosphor is made of ZnS: containing Ag and a pigment. z"O
: A fluorescent display tube comprising Zn and containing ZnO:Zn in an amount of 20 to 75% by weight of the total weight of the phosphor. (2) ZnO containing a pigment: The fluorescent light according to claim 1, characterized in that Zn contains 2 to 25% by weight of cobalt aluminate or ultramarine blue as a pigment. display tube.