JPS6092385A - Fluorescent display tube - Google Patents

Abstract

PURPOSE:To prevent lowering of brightness of a fluorescent display tube, by mixing WO8 with a specified particle diameter into a ZnO:Zn phosphor and forming a fluorescent surface with the mixt. by printing. CONSTITUTION:Powdered WO8 contg. particles with a diameter 2-30 times as large as the average particle diameter of ZnO:Zn phosphor, is mixed into the latter and a fluorescent surface of a fluorescent display tube is formed by printing with the mixt. As WO8 particles 21 are much larger than ZnO:Zn particles 11, the latter attach to the surface of the former to form a shielding layer. Thus, Zn:Zn fluorescent layer is present in an electron irradiation field when viewed from a cathode side and there is no WO8 powder surface which is essentially non-illuminant, thus lowering of brightness is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a fluorescent display tube using a ZnO:Zn phosphor as a phosphor. This invention relates to an improvement in a fluorescent display tube in which a reduction in brightness is prevented by mixing particles.

[Prior art]

A ZnO:Zn phosphor, which emits a bright bluish-green color when struck by an electron beam of 100 V or less, is mainly used for the fluorescent surface of a fluorescent display tube. This phosphor has a low emission threshold voltage and can provide sufficient luminance at about IOV, so it is currently widely used as a phosphor in fluorescent display tubes.

By the way, in general, the luminance of a phosphor varies depending on its surface condition.
If the emission efficiency changes significantly and the surface of the phosphor is contaminated with various substances, the original performance of the phosphor itself cannot be fully brought out. The same goes for the ZnO:Zn phosphor used in fluorescent display tubes, which suffers from a decrease in luminance2 luminous efficiency due to various contaminations received during the fluorescent display tube manufacturing process, or a decrease in heat resistance after tube production. (The change in brightness when the bulb is turned on after being left in a high temperature environment) may be significantly worsened.

In order to improve this point, conventionally, WOa powder is mixed into a ZnO:Zn phosphor, and as shown in FIG.
ZnO:Zn phosphor 1 with decomposition effect of ot gas etc.
There was a method to prevent contaminants from adhering to the surface of 0 as much as possible, but in this case, WOsOs powder particles 2 mixed with the phosphor were
Since the coffin was 0, it had the following drawbacks.

1. ZnO: Since the particle size of the Zn phosphor and the WOs particle size are approximately the same level, when a fluorescent surface is formed with this mixture, the phosphor exposed to the electron irradiation field seen from the cathode side is The surface area of the photon particles is reduced due to the mixed WOs particles, the effective light emitting area is reduced, and the light emission brightness is reduced.

2. ZnO: If the pWOs particle size is smaller than the Zn phosphor particle size, the surface of the phosphor is coated with Woe powder, which reduces the effective light emitting area and significantly reduces the luminance. .

[Object and structure of the invention]

In view of the above points, the present invention has been made to eliminate such drawbacks, and its gist is to adjust the particle size of the WOs powder to be mixed into the ZnO:Zn phosphor to the phosphor particle size (approximately 3
WO containing these large particles.
It is characterized by using powder a.

That is, the present invention provides ZnO: WOa powder containing WOa powder having a particle size 2 to 30 times the average particle size of the Zn phosphor.
Powder and ZnO:Zn phosphor are mixed and a fluorescent surface is formed by a printing method. According to the present invention, as shown in FIG.
The 0 particle is attached to the surface of the WOa particle 210.
, the surface of the WOs particles 21 is almost shielded by the particles of the ZnO:Zn phosphor 11. Therefore, the ZnO:Zn phosphor surface appears in the electron irradiation field seen from the cathode, and there is no WOa powder surface, which is a non-luminescent substance, so there is no reduction in luminance. In addition, since W08 powder originally has some conductivity and is reduced during the tube process and becomes conductive, the ZnO:Zn phosphor on the WOa particles can emit sufficient light without being charged up at all. Become.

Here, the WC)s powder with such a particle size distribution was used because WOs powder with various particle size distributions and Zn
After mixing with O:Zn phosphor and forming a fluorescent surface, a fluorescent display tube was prepared and the luminescence characteristics were measured.

It was found that the luminous efficiency was high, and the WOa particle size and Zn
This is because it has been found that the relationship with the O:Zn particle size greatly affects the luminance. When the WOa powder particles are 5 μm or less, the brightness is 20 to 30% lower than that of the fluorescent surface of the present invention.
Moreover, if the diameter becomes larger than 90 μm, screen printing becomes impossible and formation of a 1L fluorescent surface becomes impossible.

Further, the mixing amount of the WOs powder with respect to the ZnO:Zn phosphor was preferably in the range of 5 to 25 wt%. Table 1 below shows the brightness 1 luminous efficiency of each fluorescent surface and the slump rate after being left at high temperatures with respect to the mixing amount. (This test uses conditions that are more severe than normal conditions in order to see the difference in slump rate.) 4-Table 1 As can be seen from this table, brightness, luminous efficiency, slump (by W08 mixture) Both rates were significantly improved, especially between 10 and 2.
The range of 5 wt% shows very good characteristics in both luminance and luminous efficiency. Although it can be applied to the case of 5wt% mixture,
In the 3Qwt% mixture, there are too many non-light emitting elements and the brightness is 1.
Since the luminous efficiency has decreased, it is practically 5 to 25 wt.
% mixing range was good.

Next, the present invention will be explained in detail.

〔Example〕

ZnO with an average particle size of 2.4 μm: 5 to 80 to Zn phosphor
A phosphor paste was prepared by mixing 20 wt% of WOs powder containing 70% μm particles and kneading it with a printing binder. Next, a fluorescent surface was printed in a predetermined shape using a screen with a coarse mesh diameter, and a display tube was completed through the fluorescent display tube manufacturing process.

After being made into tubes, we measured the luminescent properties of the fluorescent display tubes and found that both luminance and luminous efficiency were improved by 32 to 40% compared to the fluorescent surface that did not contain any WOa powder, and after being left at high temperatures. Even the brightness slump rate of
There was a significant improvement of around %. In addition, a phosphor surface prepared by mixing WOs particles having approximately the same particle size as a ZnO:Zn phosphor had a brightness lower than that of conventional phosphors and could not be used.

〔Effect of the invention〕

As explained above, the present invention provides ZnO for a fluorescent display tube:
Zn phosphor surface, ZnO: WOs powder containing WOa powder with a larger particle size than Zn phosphor particles, and ZnO:
By mixing Zn with a phosphor and using this mixture to form a fluorescent surface by a printing method, Zn is added to the surface of the WO8 particles.
Since the O:Zn phosphor is attached, the surface of the phosphor is exposed to the electron irradiation field seen from the cathodeJ), and the brightness decreases because there is no non-light emitting area due to WOB particles. It disappears. In addition, since it contains large particles of WOs powder, the amount of binder used during fluorescent surface printing can be reduced, which has the effect of reducing contamination caused by binder combustion on the surface of the fluorescent material.

[Brief explanation of drawings]

FIG. 1 is a schematic illustration of a conventional fluorescent surface, and FIG. 2 is a schematic illustration of a fluorescent surface according to the present invention. i 1 @---ZnO: Zn phosphor, 21ee*eW
Oa particles. Patent Applicant Ise Electronics Co., Ltd. Agent Masaki Yamakawa (1 idiot) 1st - 2nd Figure / Shell - 20 = 10 1 21

Claims (1)

[Claims] (1) ZnO of a fluorescent display tube: On the Zn fluorescent surface, Zn
O: Mix WOa powder containing WOs powder with a particle size 2 to 30 times the average particle size of the Zn phosphor and a ZnO:Zn phosphor, and use this mixture to form a fluorescent surface by a printing method. A fluorescent display tube comprising: (21WOa powder is 5 to 25% compared to ZnO:Zn phosphor.
The fluorescent display tube according to claim 1, wherein the fluorescent display tube is mixed in a range of wt%.