JPS5917755B2 - Red-emitting slow electron beam excitation fluorescent display tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel low-speed electron beam-excited fluorescent display tube that emits red light, and more specifically, the present invention relates to a novel fluorescent display tube that emits red light, and more specifically, the present invention relates to a novel fluorescent display tube that emits red light. This invention relates to a low-speed electron beam excitation fluorescent display tube that emits light.

As is well known, a low-speed electron beam-excited fluorescent display tube consists of an anode plate having a fluorescent film on one side, and a cathode facing the fluorescent film, enclosed in a vacuum container. The fluorescent film 5 on the anode plate is excited by a low-speed electron beam emitted from the cathode to emit light.

Figures 1 and 2 show a low-speed electron beam-excited fluorescent display tube (hereinafter referred to as "
1 is a schematic configuration diagram of a typical example of a fluorescent display tube (abbreviated as "fluorescent display tube"), in which FIG. 1 shows a diode tube, and FIG. 2 shows a triode tube.
As shown in FIGS. 1 and 2, a fluorescent film 12 is provided on one side of an anode plate 11 made of an aluminum plate or the like. Anode plate 11 is supported by ceramic substrate 13. A cathode 14 is provided opposite the fluorescent film 12 provided on one side of the anode plate 11, and the fluorescent film 12 is excited to emit light by a low-speed electron beam emitted from the cathode 14 or j5. In particular, in the triode shown in FIG. 2, a grid electrode 15 is provided in the gap between the cathode 14 and the fluorescent film 12 for controlling or diffusing the low-speed electron beam emitted from the cathode 14. Note that in the fluorescent display tubes shown in Figures 1 and 2, one cathode 1 is used.
Although four cathodes are used, if the fluorescent film 12 has a large area, two or more cathodes may be provided, and the number is not particularly limited. The anode plate 11 having a fluorescent film 12 on one side, the ceramic substrate 13 and the cathode 14 (FIG. 1) or the anode plate 11 having a fluorescent film 12 on one side.
, the ceramic substrate 13, the cathode 14, and the grid electrode 15 (Fig. 2) are sealed in a transparent container 16 made of glass or the like, and the internal IT is kept at a high vacuum of 10-5 to 104 0 Torr. There is. Conventionally, zinc-activated zinc oxide phosphor (
ZnO-Zn) is known. This phosphor is produced by firing zinc oxide (ZnO) in a reducing atmosphere or by
It is obtained by adding a small amount of a zinc compound such as zinc sulfide (ZnS) to Zn0 and firing it in air, and when excited with a slow electron beam, it emits high-intensity green-white light.

Fluorescent display tubes having the above-mentioned structure having a fluorescent film made of ZnO:Zn are widely used industrially, for example, as display elements for desktop electronic computers, various measuring instruments, and the like. As described above, fluorescent display tubes using ZnO:Zn as a fluorescent film are in practical use, but there are almost no known fluorescent materials other than ZnO:Zn that emit light through slow electron beam excitation. In the past, almost no fluorescent display tubes using a fluorescent film made of a phosphor other than ZnO:Zn have been known. An object of the present invention is to provide a novel fluorescent display tube that emits high-intensity red light by excitation with a slow electron beam.

The present inventors have conducted various experiments with the aim of obtaining a phosphor that emits high-brightness light by slow electron beam excitation and a fluorescent display tube using the phosphor. Ta.

As a result, the general composition formula (where X is 0.04 to 0.90
The europium-activated composite oxide phosphor (with a value in the molar range and a in the range of 0.01 to 0.3 gram atom) has been shown to exhibit high-intensity red light emission under slow electron beam excitation. This led to the invention of a red-emitting fluorescent display tube using this phosphor as a fluorescent film. That is, the present invention provides a fluorescent display tube having a structure in which an anode plate having a fluorescent film on one side and a cathode facing the fluorescent film are enclosed in a vacuum container. of(
The invention is characterized in that it is a europium-activated composite oxide phosphor represented by the general compositional formula (where X and a have the same definitions as above).

The phosphor used as the phosphor film of the fluorescent display tube of the present invention represented by the above general compositional formula emits particularly high-intensity red light when manufactured using the following two types of raw materials. One is ZnO or a zinc compound that can be easily converted to ZnO at high temperatures such as carbonate, sulfate, oxalate, or hydroxide as a raw material, and its general compositional formula is (where a is 0.01 to 0.
．． 3 gram atom range) with a europium-activated yttrium vanadate phosphor.

Europium-activated yttrium vanadate phosphor is a phosphor that is used as a phosphor for the red light emitting component of cathode ray tubes for color television (in this case, especially Eu3
A phosphor with a + activation amount a in the range of 0.01 to 0.06 gram atom is used), therefore, it is an activator when excited by an electron beam with an accelerating voltage of several W. It exhibits high-intensity red light emission with good color purity characteristic of Eu3+, but hardly any light is emitted by low-speed electron beam excitation. ZnO or a zinc compound that can be easily converted to ZnO at high temperatures and a europium-activated yttrium vanadate phosphor have a ratio of 0.04 to 0.90 mol of the europium-activated yttrium vanadate phosphor per mole of ZnOl. This mixture is used as the raw material for the phosphor. Note that the Eu3+ activation amount a of the europium-activated yttrium vanadate phosphor, which is a raw material component, is preferably in the range of 0.04 to 0.
．． One gram atom. A more preferable range of the mole number of the europium-activated yttrium vanadate phosphor to be mixed with respect to the mole of ZnOl is 0.20 to 0.60 mole, and when the number of moles is about 0.38 mole, the red light emission by Eu3+ is the best. A strong fluorescent material is obtained. The other raw materials are ZnO or zinc compounds that can be easily converted to ZnO at high temperatures such as carbonates, sulfates, oxalates, and hydroxides, and yttrium oxide (Y2O3), oxalates, and carbonates that can be easily converted to ZnO at high temperatures. Yttrium compound that can be converted into Y2O3 and europium oxide (Eu2O3) or oxalate,
This method uses a mixture of a europium compound, such as carbonate, which can be easily converted to EU2O3 at high temperatures, and a vanadium compound, such as vanadium pentoxide (V2O5) or ammonium vanadate, which can be easily converted to V, O5 at high temperatures.

In this method, each of the above raw materials is (1) EU2O3a
mole (however, a is in the range of 0.01 to 0.3), Y2O3 is (1-a) mole, (1;) the EU2O
3 and Y2O3 has the composition formula (Y1-8
, EUa) 1 mol of V2O5 per 1 mol of mixed rare earth oxide represented by 203, 1 mol of the above EU2O3, Y2O3 and 205 per 1 mol of Zn0 has the composition formula (Y1-0.Eua)VO4. The mixed oxide represented above is mixed in a proportion of 0.04 to 0.90 mol, and is used as a raw material for the phosphor of the present invention.

Note that the more preferable range of the number of moles a of EU2O3 used as a raw material component is 0.04 to 0.1 mole. Also, 1 mole of EU2O3Y2O and V2O5 mixed with ZnOl mole has the composition formula (Y1-0.E
A more preferred range of the number of moles of the mixed oxide represented by ua)04 is 0.20 to 0.60 moles, approximately 0.
．． When the amount is 38 mol, a phosphor exhibiting the strongest red luminescence due to Eu3+ is obtained. When using any of the above-mentioned raw materials, the raw materials are physically sufficiently ground and mixed using a ball mill, mixer mill, etc., and are then filled into a firing container such as a quartz crucible or an alumina crucible, and then fired. In addition, when using the latter raw material, Y3+ and Eu3+ are first converted into oxalates, taking advantage of the similarity in chemical properties of rare earth elements.
After co-precipitating as carbonate etc., filtering and drying, ZnO
By adding predetermined amounts of and V2O5 and pulverizing and mixing, each raw material component can be mixed better. Also Y3+, E
A method of co-precipitating u3+ and Zn2+ as oxalate, carbonate, etc. can also be used, but in this case, since the chemical properties of rare earth elements and zinc are different, the above-mentioned Y3+ and Eu3+ may be added in excess, etc. Compared to the case of precipitation, it is necessary to specify conditions for precipitation formation more strictly. Firing is performed in air, and the firing temperature is suitably 800 to 1200°C.

If the firing temperature is lower than 800°C, the reaction will be insufficient and a phosphor that emits light with high brightness will not be obtained. If the sintering temperature is higher than 1200° C., sintering occurs and a phosphor that emits light with high brightness cannot be obtained. A particularly preferred firing temperature range is 900 to 1100°C. The firing time varies depending on the filling amount of the phosphor raw material, the size of the firing container, etc., but it is required to be at least 30 minutes, and if it is shorter than 30 minutes, the reaction will be insufficient. A more preferable firing time range is 1 to 3 hours. In the manufacturing method described above, as long as the firing conditions are within the above-mentioned range, the firing process may be performed two or more times, such as by pulverizing and mixing the once-fired product and then firing it again. = of the phosphor obtained by the above manufacturing method
The general chemical formula is expressed as described above.

Here, X is in the range of 0.04 to 0.90 mol, and a
is in the range of 0.01 to 0.3 gram atom. When the value of X is less than 0.04 mol, red light emission due to Eu3+ is no longer observed, and light is emitted to the extent that green light emission is only slightly observed. If the value of X is greater than 0.90 mol, the phosphor will not emit light at all under slow electron beam excitation. Next, a method for manufacturing the fluorescent display tube of the present invention will be explained. First, a europium-activated composite oxide phosphor is coated by precipitation coating onto an anode plate, usually supported by a ceramic substrate, to form a phosphor film. That is, an anode plate is placed in a suspension of phosphors dispersed in water,
The phosphor is deposited on one side of the anode plate by its own weight and then applied, after which the water is removed and the coating is allowed to dry. In this case, a small amount (0.01-1%) is added to the suspension to improve the adhesion of the resulting fluorescent film to the anode plate.
of water glass may be added. In addition, the phosphor coating density is 5
m9/C77l~30~/Cd is suitable. Although the above-mentioned precipitation coating method is generally used as a method for forming a fluorescent film and is widely practiced, the method for forming a fluorescent film in the fluorescent display tube of the present invention is not limited to this precipitation coating method. . Next, the linear heater was heated with BaO, SrO. A cathode coated with an oxide such as CaO is placed facing the fluorescent film on the anode plate with an interval of approximately 5 mm, and this pair of electrodes is placed in a transparent container such as glass. Vent the inside of the container. The inside of the container is at least 10AT0rr. After reaching the above degree of vacuum, exhaust is stopped and sealing is performed. After sealing, the getter is removed to further increase the degree of vacuum inside the container. In this manner, the fluorescent display tube of the present invention can be obtained. The phosphor film on the anode plate is flat and the cathode is linear, so in order to diffuse the low-speed electron beam emitted from the cathode, a diffuser is placed between the cathode and the phosphor film as shown in Figure 2. It is preferable to install a mesh-like grid electrode as the electrode. In this case, better results can be obtained if the mesh is as narrow as possible so that the loss of the amount of light emitted by the fluorescent film is small and the low-velocity electron beam is well diffused. Specifically, it is desirable that the diameter of the mesh is 500 microns or less, and the aperture ratio (the area of the holes through which the low-speed electron beam passes, relative to the total area of the grid electrode) is 50% or more. The anode plate can display any character or figure by dividing its electrode form into the required character or figure shapes and making it possible to selectively apply the required voltage to each electrode. be able to. In addition, the anode plate is divided into dots or lines, and a fluorescent film made of europium-activated composite oxide phosphor is formed on some of the electrodes, and a phosphor film made of europium-activated composite oxide phosphor is formed on the other electrodes. A fluorescent display tube capable of displaying multiple colors can be obtained by forming a fluorescent film made of a fluorescent material for excitation of slow electron beams whose emission color is different from that of the light material. FIG. 3 shows the relationship (curve a) between the anode plate voltage (acceleration voltage) and luminance of the fluorescent display tube of the present invention at YVO
4: The same relationship in a display tube with Eu as a fluorescent film (curve b
), and as is clear from FIG. 3, in the fluorescent display tube of the present invention, in the case of a display tube whose fluorescent film is YVO4:Eu, the luminance decreases rapidly and almost no light is emitted. It exhibits high-intensity red light emission under slow electron beam excitation at an anode plate voltage of 100 V or less. Figure 4 shows the general composition formula of ZnO-X (Y, ., 6, EuO.O4)
2 is a graph showing the relationship between the value of X and the intensity of red light emission in a fluorescent display tube of the present invention in which the fluorescent material No. 04 is used as a fluorescent film. As is clear from Figure 4, the value of x is 0.20 to 0.6.
When the value of X is in the range of 0 mol, a fluorescent display tube with stronger red emission can be obtained, and especially when the value of X is about 0.38 mol, a fluorescent display tube with the highest red emission intensity can be obtained.
Furthermore, when the Eu3+ activation amount a is outside the above-mentioned range, the intensity of red light emitted by Eu3+ is significantly reduced. A more preferable range of Eu3+ activation amount a is 0.04 to 0.1 gram atom. FIG. 5 shows the emission spectrum of the fluorescent display tube of the present invention, which shows that the fluorescent display tube of the present invention emits red light. As described above, the present invention provides a fluorescent display tube that emits high-intensity red light through low-speed electron beam excitation, and such a red-emitting fluorescent display tube has never existed before. Therefore, its industrial utility value is great.

Next, the present invention will be explained with reference to Examples.

Example 1 One mole of zinc oxide (ZnO) and its composition formula (YO.96
, EUO. O4) After thoroughly grinding and mixing 0.38 mol of europium-activated yttrium vanadate phosphor represented by VO4 using a mixer mill, it was packed in an aluminum crucible and fired in an electric furnace at 1000°C for 2 hours in air. By doing this, a phosphor whose compositional formula is represented by was obtained.

2 (1771
A fluorescent film with a coating density of approximately 10/Cd was formed on an aluminum anode plate of After placing the pair of electrodes in a hard glass container, facing each other with an interval of about 5 cm, the inside of the container was evacuated.The degree of vacuum in the container was 10-
After reaching a degree of vacuum of about 5T0rr, the evacuation was stopped and the container was sealed, and then the getter was removed to further increase the degree of vacuum inside the container. In this way, a fluorescent display tube having the structure shown in FIG. 1 was obtained. This fluorescent display tube has an anode plate voltage of 8
When the voltage was 0 V, the cathode voltage was 1.0 V, and the current was 50 mA, red light was emitted with a luminance of 2.5 ft-L. Example 2 1 mol of zinc carbonate (ZnCO3) and its composition formula (YO
．． , 4, EuO. After sufficiently pulverizing and mixing 0.38 mol of europium-activated yttrium vanadate phosphor represented by O6)04 using a mixer mill, the mixture was packed in an aluminum crucible and fired in an electric furnace at 1100°C for 1 hour in air. By doing this, a phosphor whose compositional formula is represented by was obtained.

A fluorescent display tube was produced in the same manner as in Example 1 except that the phosphor thus obtained was used. This fluorescent display tube has an anode plate voltage of 80V, a cathode voltage of 1.0V, and a current of 5V.
At 0 mA, red light was emitted with a luminance of 2.0 ft-L. Example 3 The above rare earth oxide was dissolved in nitric acid slightly in excess of the stoichiometric amount, and then pure water was added to make a 5% aqueous solution and heated to about 80°C.

When a 10% oxalic acid aqueous solution heated to about 80°C is poured into this while stirring until the amount of oxalic acid (H2C2O4.2H20) is about 20% in excess of the stoichiometrically required amount, rare earth oxalate A coprecipitated mixture was obtained. This was filtered and dried at 150°C for 2 hours. After adding to the rare earth oxalate coprecipitation mixture obtained in this way and sufficiently pulverizing and mixing using a mixer mill, the mixture was packed in an aluminum crucible and fired in an electric furnace at 1000°C for 2 hours in air. A phosphor whose compositional formula is represented by the following was obtained.

A fluorescent display tube was produced in the same manner as in Example 1 except that the phosphor thus obtained was used. This fluorescent display tube has an anode plate voltage of 80V, a cathode voltage of 1.0V, and a current of 50V.
mA, red light was emitted with a luminance of 3.0 ft-L. Example 4 A coprecipitated mixture of rare earth oxalates was obtained from the rare earth oxides in the same manner as in Example 3.

was added to the rare earth oxalate coprecipitate mixture, sufficiently pulverized and mixed using a mixer mill, and then packed in an alumina crucible and fired in an electric furnace at 1000°C for 2 hours in air to determine its composition formula. A phosphor represented by was obtained.

A fluorescent display tube was produced in the same manner as in Example 1 except that the phosphor thus obtained was used. This fluorescent display tube has an anode plate voltage of 80V, a cathode voltage of 1.0V, and a current of 50V.
mA, red light was emitted with a luminance of 2.5 ft-L. Example 5 A coprecipitated mixture of rare earth oxalates was obtained from the rare earth oxides in the same manner as in Example 3.

was added to the rare earth oxalate coprecipitate mixture, sufficiently pulverized and mixed using a mixer mill, and then packed in an alumina crucible and fired in an electric furnace at 1000°C for 2 hours in air to determine its composition formula. A phosphor represented by was obtained.

A fluorescent display tube was produced in the same manner as in Example 1 except that the phosphor thus obtained was used. This fluorescent display tube has an anode plate voltage of 80, a cathode voltage of 1.0, and a current of 507.
When it was set to 71A, red light was emitted with a luminance of 2.0 ft-L. Example 6 After sufficiently pulverizing and mixing the above materials using a mixer mill, the phosphor whose composition formula is represented by Obtained.

A fluorescent display tube was produced in the same manner as in Example 1 except that the phosphor thus obtained was used. This fluorescent display tube has an anode plate voltage of 80V, a cathode voltage of 1.0V, and a current of 5V.
At 0 mA, red light was emitted with a luminance of 2.1 ft-L.

[Brief explanation of drawings]

FIGS. 1 and 2 are schematic diagrams of typical examples of fluorescent display tubes, with FIG. 1 showing a diode and FIG. 2 showing a triode. 11... Anode plate, 12... Fluorescent film, 13... Ceramic substrate, 14...
・Cathode, 15... Grid electrode, 16...
Container, 17...Inside the display tube kept in high vacuum. In Figure 3, the composition formula is ZnO-0,38 (YO.96, EUO.O4) VO4
Relationship between anode plate voltage and luminance in a fluorescent display tube of the present invention using a phosphor shown as a phosphor film (curve a)
Compare this with the relationship between anode plate voltage and luminance (curve b) in a display tube whose phosphor film is a europium-activated yttrium vanadate phosphor whose composition formula is (YO.96, EUO.O4)VO4. This is a graph shown as follows. Figure 4 shows a general compositional formula of ZnO-X (YO.9EuO.
2 is a graph showing the relationship between x value (mol) and red light emission intensity in a fluorescent display tube of the present invention using a phosphor represented by O4)04 as a fluorescent film.

Claims (1)

[Claims] 1. In a low-speed electron beam-excited fluorescent display tube having a structure in which an anode plate having a fluorescent film on one side and a cathode facing the fluorescent film are enclosed in a vacuum container, The film is ZnO・X (Y_1_-_a, Eu_a
) VO_4 (wherein, X is in the range of 0.04 to 0.90 mol, and a is in the range of 0.01 to 0.3 gram atom). A low-speed electron beam-excited fluorescent display tube comprising: