JPH0823010B2 - Low-speed electron beam excitation fluorescent display tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention mainly relates to low-speed electrons using a phosphor that exhibits high-efficiency light emission under low-speed electron beam excitation with an accelerating voltage of 1 kV or less, particularly 100 V or less, as a fluorescent film. The present invention relates to a line excitation fluorescent display tube (hereinafter abbreviated as “fluorescent display tube”).

[Prior Art] As is well known, a fluorescent display tube has an anode plate having a fluorescent film on one surface and a cathode provided so as to face the fluorescent film, which is enclosed in a container having a vacuum inside. That is, the low-speed electron beam emitted from the cathode (generally, a low-speed electron beam with an acceleration voltage of 100 V or less) excites the fluorescent film on the anode plate to emit light. This fluorescent display tube is widely used as a display element for various measuring instruments and the like.

As the low-speed electron beam phosphor used as the fluorescent film of the fluorescent display tube, zinc-activated zinc oxide phosphor (ZnO: Zn) has long been used as a representative phosphor exhibiting highly efficient green-white emission. However, as the field of use of fluorescent display tubes has expanded, it has become necessary to diversify the emission color of fluorescent display tubes, and along with this, the development of phosphors that emit light other than green under slow electron beam excitation is proceeding. I've been. As a result (Zn
_1-x , Cdx) S: Ag phosphors such as zinc sulfide / cadmium phosphors and mixtures of these phosphors with conductive materials such as indium oxide (In ₂ O ₃ ). The following luminescent composition has been developed (JP-A-55-23104 and JP-A-55-231).
06, Japanese Patent Sho 59-33153, Japanese Patent Sho 59-33155, Real Official Sho
60-6414, etc.), and is partially put to practical use as a fluorescent display tube.

[Problems to be Solved by the Invention] However, the above-mentioned light-emitting composition also has a problem that the luminous efficiency is lower than that of the above-described ZnO: Zn phosphor that emits green light, and sufficient emission luminance cannot be obtained. For this reason, when the fluorescent film made of the above-mentioned light emitting composition and the fluorescent film made of ZnO: Zn are used together in one fluorescent display tube, the emission luminances of the two are different and the display is difficult to see. Due to the difference in voltage, inconvenience such as a complicated drive circuit occurs. Therefore, there is a demand for a light-emitting material that emits light other than green light under high-speed electron beam excitation and has higher light emission efficiency.

The present invention has been made under the above circumstances,
It is an object of the present invention to provide a low-speed electron beam excitation fluorescent display tube having higher brightness than conventional ones.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the inventors of the present invention have an oxide-based phosphor having a high emission efficiency under a relatively slow electron beam excitation as compared with the oxide-based phosphor. As a result of various studies on the production method, additive effect, etc. of these phosphors, in particular, phosphorous (Cu) was added to Cu-Ag- or Au-activated (Zn _1-x , Cdx) S-based phosphors. By adding and containing P), the emission brightness under the excitation of a low-speed electron beam is improved, and further, in this phosphor,
The inventors have found that the emission luminance is further improved by mixing a conductive substance such as In ₂ O _{3 and} have completed the present invention.

That is, the fluorescent display tube of the present invention is a fluorescent display tube having a structure in which an anode plate having a fluorescent film on one surface and a cathode facing the fluorescent film are enclosed in a container having a vacuum inside. The film has the general formula (Zn _1-x , Cdx) S: a
It is characterized by comprising a light emitting material which is a P-containing sulfide-based phosphor represented by M, bX, or cP or a mixture of the P-containing sulfide-based phosphor and a conductive substance.

 Hereinafter, the present invention will be described in more detail.

The P-containing sulfide-based phosphor used in the present invention is manufactured in the same manner as the conventional sulfide-based phosphor except that a phosphorus compound is used as one of the phosphor raw materials. That is, raw zinc sulfide (ZnS) and raw cadmium sulfide (CdS), which are the constituent materials of the matrix, and Cu, Ag or Au compound that becomes the activator (M) {eg CuSO ₄ , Ag (NO ₃ ), HAuCl _4, etc., a monovalent metal halide (NaCl, etc.) or an aluminum compound {Al (NO ₃ ) ₃ , Al ₂ (SO ₄ ) _3, etc.) that serves as a co-activator (X), and a compound containing phosphorus {eg, Na ₃ PO ₄ ,, K ₃ PO ₄ ,, (NH ₄ ) ₃ PO ₄ , H ₃ P
O ₄ ,, Zn ₃ (PO ₄ ) ₂ ,, Cd ₃ (PO ₄ ) ₂ ,, AlPO ₄ ,, (NH ₄ ) ₄ P ₂ O ₇ ,, Na ₄ P
₂ O ₇ ,, K ₄ P ₂ O ₇ ,, Zn ₂ P ₂ O ₇ ,, Cd ₂ P ₂ O ₇ ,, H ₄ P ₂ O ₇ ,, P ₂ O ₅ etc. stoichiometrically (Zn _1-x , Cdx) S: aM, bX, cP are weighed so that they have the composition, mixed well, packed in a heat-resistant container, and placed in the air or a sulfide atmosphere such as hydrogen sulfide atmosphere, sulfur dioxide, carbon disulfide atmosphere. It can be produced by baking at 700 ° C. to 1100 ° C. for 0.5 to 6 hours, thoroughly washing with water, alcohol, dilute mineral acid, dehydration, and drying.

FIG. 1 shows one of the phosphors used in the present invention (Zn
_0.65 , Cd _0.35 ) S: Ag, Cl, cP Illustrates the relationship between the amount of P (c value) contained in the phosphor and the emission brightness when the phosphor is excited by a slow electron beam with an accelerating voltage of 30V. The horizontal axis represents the weight (g) of P contained in the phosphor matrix {(Zn _1-x , Cdx) S} 1g, and the vertical axis represents the emission brightness of each phosphor.
It is shown as a relative value with respect to the emission brightness of a conventional phosphor (c = 0) not containing. As you can see from Figure 1, P
When the content (c) of P is increased, the obtained emission brightness is gradually increased, but when the content of P is larger than 10 ^-2 g / g, the emission brightness is lower than that of the conventional phosphor containing no P. Although not shown, when the composition of the phosphor base is changed in the phosphor used in the present invention (when x is other than 0.35)
Also, the activator (M) and the co-activator (X) are each Ag.
In the case of other than Cl and Cl, the luminescent color of the obtained phosphor and the degree of increase in luminescent brightness due to the addition of P are different from each other, but there is a difference between the added amount of P (c value) and the luminescent brightness as shown in FIG. It was confirmed that there is a correlation almost similar to the relationship exemplified in.

As described above, when the P content c increases in the phosphor used in the present invention, the emission brightness of the phosphor obtained under the slow electron beam excitation is gradually reinforced, but the c value is 10 ^-2 g / g or less. Since it becomes lower than that of a conventional sulfide-based phosphor that does not contain P, the P content (c value) is preferably greater than 0 and 10 ^-2 g / g or less, and particularly c Value 10 ^-4 g
The range of / g to 5 × 10 ⁻³ g / g is more preferable in terms of emission brightness. Further, in the phosphor used in the present invention, the content (a) of M which is an activator and the content of X which is a co-activator are 0 <a ≦ 5 in terms of emission brightness.
It is preferably in the range of × 10 ⁻³ g / g and 0 <b ≦ 10 ⁻² g / g, more preferably 1 × 10 ⁻⁴ g / g ≦ a ≦ 1 × 10.
^-3 g / g and 1 x 10 ^-4 g / g ≤ b ≤ 2 x 10 ^-3 g / g are preferred.

In addition, when the activator (M) is Ag among the phosphors used in the present invention, the addition of P remarkably increases the emission luminance.

Phosphors used in the present invention also include this and, for example, In ₂ O.
Conductive metal oxides such as ₃ , SnO ₂ , ZnO and CdS, In ₂ S ₃ , Cu
₂ S, than the phosphor alone by mixing the conductive metal is at least one in the conductive metal sulfides such as Li ₂ S, luminescent composition exhibiting higher luminance by receiving a low voltage electron beam excitation The thing is obtained. As the conductive material used at this time, In ₂ O ₃ , ZnO, SnO ₂
It is preferable to use a conductive metal oxide such as In ₂ O
_It is more preferable to use ₃ . The amount of these conductive substances added depends on the particle size of the conductive substance used and the method of mixing the same with the phosphor, but in the case of a conventional luminescent composition comprising a mixture of the phosphor and the conductive substance, Similarly, when the particle diameter (median value) of the conductive substance is larger than about 2 μ, it is preferable to set it to about 10 to 90% by weight of the entire light emitting composition, and the conductive substance having a particle diameter smaller than about 2 μ is used. If used, it is preferably about 0.2 to 10% of the entire light emitting composition. The phosphor used in the present invention is obtained by mixing the phosphor and the conductive substance by a known method such as a dry mixing method or a wet mixing method using a ball mill or a mixer mill, or a method of attaching the conductive substance to the surface of the phosphor. It is possible to obtain a light emitting material composed of a body and a conductive substance.

On the other hand, the fluorescent display tube of the present invention is characterized by containing at least the above-mentioned P-containing sulfide-based fluorescent material in its fluorescent film, and other structures are the same as those of conventionally known fluorescent display tubes. It may be 2 and 3
The figure is a schematic configuration diagram showing an example of a fluorescent display tube of the present invention,
FIG. 2 shows a diode and FIG. 3 shows a triode. In these fluorescent display tubes, a fluorescent film 12 is provided on one surface of an anode plate 11 made of an aluminum plate or the like. The anode plate 11 is supported by the ceramic substrate 13. A cathode 14 is provided so as to face the fluorescent film 12 provided on one surface of the anode plate 11, and the fluorescent film 12 is excited by a low-speed electron beam emitted from the cathode 14 to emit light. Particularly in the triode of FIG. 3, the cathode 14 and the fluorescent film
A grid electrode 15 for controlling or diffusing a low-speed electron beam emitted from the cathode 14 is provided in the gap between the lattice electrode 12 and the electrode 12. Although one cathode 14 is used in the fluorescent display tube shown in FIGS. 2 and 3, two or more cathodes may be provided when the area of the fluorescent film 12 is large. ,
The number is not particularly limited. The anode plate 11 having a fluorescent film on one surface, the ceramic substrate 13 and the cathode 14 (second
(Or) an anode plate 11 having a fluorescent film 12 on one side,
Ceramic substrate 13, cathode 14 and grid electrode 15 (Fig. 3)
Is enclosed in a transparent container 16 such as glass, and the inside 17 thereof is kept at a high vacuum of 10 ⁻⁷ Torr or more.

The fluorescent display tube of the present invention is produced, for example, by the method described below. That is, first, the above-described phosphor used in the present invention is mixed with a suitable organic binder, and the obtained paste-like phosphor is poured onto an anode plate and rubbed with a squeegee to form a phosphor film having a desired shape on the anode plate. To form. The fluorescent film thus formed is baked in air to decompose the organic binder present in the fluorescent film. The method for producing the fluorescent film in the fluorescent display tube of the present invention is not limited to such screen printing. Next, a cathode formed by coating a linear tungsten heater with an electron emitting agent such as BaCO ₃ or SrCO ₃ is arranged facing the fluorescent film on the anode plate with an interval of 5 mm or less. Then, the pair of electrodes and the getters such as Ba and Ti are placed in a transparent container made of glass or the like, the gas in a vacuum is baked, and the cathode is energized while evacuating with a vacuum pump to activate the electron emitting agent. , At least 10 ^-3 To inside the container
Seal after reaching a vacuum level of rr or higher. After sealing, the getter is blown to increase the degree of vacuum in the container to obtain the fluorescent display tube of the present invention.

[Examples] Next, the present invention will be described by examples. Needless to say, the present invention is not limited to the examples below.

(Example) ZnS550g, CdS450g, AgNO ₃ aqueous solution (containing 5 × 10 ⁻² g / Ag) 40 cc, NaCl 2.8 g and Na ₄ P ₂ O ₇ · 10H ₂ O 7.2 g were weighed and mixed sufficiently. After that, it was packed in an alumina crucible, covered with a lid, calcined in the air at a temperature of 900 ° C for 2 hours, taken out of the furnace, washed with water, dried, and sieved to adjust the particle diameters of Ag, Cl and P. Content of 2 × 10 ^-4 g each
/ g, 10 ^-4 g / g and 10 ^-3 g / g (Zn _0.64 , Cd _0.36 ) S: (2
^{X10 -4} g / g) Ag, (10 ^-4 g / g) Cl, (10 ^-3 g / g) P phosphor (phosphor [1]) was obtained.

Separately, for comparison, the contents of Ag and Cl are 2 × 10 ⁻⁴ g / g and the same as in the above phosphor [1] except that Na ₄ P ₂ O ₇ · 10H ₂ O is not used. 10 ^-4 g / g (Z
n _0.64 , Cd _0.36 ) S: (2 × 10 ⁻⁴ g / g) Ag, (10 ⁻³ g / g) Cl phosphor (phosphor [R1]) was obtained.

Furthermore, the phosphor material used in the same manner as the phosphor [1] and the phosphor [R1] was used, except that the phosphor materials used were stoichiometrically mixed and weighed so as to have the composition shown in Table 1. 20 types of phosphors having the composition shown in 1 (phosphors [2], [3] ...
[11], phosphors [R2], [R3] ... [R11]) were manufactured. Here, phosphors [7], [R7], [10] and [R10]
CuSO ₄ .5H ₂ O was used as the Cu supply source, and HAuCl ₄ was used as the Au supply source for the phosphors [8], [R8], [11] and [R11]. Further, Na ₄ P ₂ O ₇ · 10H ₂ O was used as the source of P except that K ₃ PO ₄ was used as the P source of the phosphor [6] and the phosphor [R6].

10 mg of each phosphor thus produced was added to 100 cc of distilled water and ultrasonically dispersed. Put a 2 cm × 1 cm aluminum plate in this dispersion, leave it for 30 minutes, remove the supernatant, dry to form a fluorescent film, and irradiate a low-speed electron beam with an accelerating voltage of 30 V with a demountable electron beam irradiation device. Then, the emission brightness was measured, and as shown in Table 1, phosphors containing P (phosphors [1], [2] ...
... [11]) has a significantly improved emission luminance as compared with the phosphors (phosphors [R1], [R2], ... [R11]) that do not contain P except one.

In addition, phosphors [1] to [11] and phosphors [R1] to
[R11] is mixed into a binder consisting of ethyl cellulose and carbitol to form an ink, which is applied on the plate using a silk screen and heated at 450 ° C for 30 minutes to provide fluorescent display using a fluorescent film. A tube was prepared, operated at an accelerating voltage of 30 V, and the emission brightness was measured. As a result, a phosphor containing no P (phosphor [R1] to [R11])
The fluorescent display tubes having the fluorescent film made of the phosphor containing P (phosphors [1] to [11]) had remarkably high emission brightness as compared with the fluorescent display tube having the fluorescent film made of.

Furthermore, 22 kinds of phosphors illustrated in Table 1 (phosphors [1], [2], [3] ... [R1], [R2], [R3] ...
... and [R11]), each phosphor and In ₂ O ₃ (average particle size 0.8 μ) were mixed in a ball mill in water at a weight ratio of 199/1 and the slurry was evaporated to dryness to obtain 22 kinds of After preparing the luminescent materials, 22 types of fluorescent display tubes having fluorescent films made of these luminescent materials on the anode plate were prepared in the same manner as above, and comparison was made between fluorescent display tubes containing phosphors of the same composition. Then, towards the fluorescent display tube towards the fluorescent display tube consisting of light-emitting material containing in ₂ O ₃ is made of a luminescent material containing no in ₂ O ₃ was higher emission luminance. Also P
A fluorescent display tube made of a light-emitting material using a phosphor containing phosphor (phosphors [1], [2] ... [11]) does not contain P (phosphors [R1], [R2] ... [ R11]) was compared to fluorescent display tubes made of a luminescent material, and fluorescent display tubes using phosphors having the same composition except for the presence / absence of P showed high-intensity light emission.

[Effects of the Invention] As described in detail above, according to the present invention, (Zn _1-x , Cdx) S: a
M, made by adding a certain amount of P in the sulfide-based phosphor represented by _{bX (Zn 1-x, Cdx} ) S: aM, bX, cP phosphor under low voltage electron beam excitation of a conventional (Zn _{1 -x} , Cdx) S: aM, bX The emission brightness of the phosphor is significantly increased compared to that of a phosphor, and a fluorescent display tube having a phosphor film containing this phosphor is a conventional fluorescent display having a phosphor film made of a sulfide-based phosphor. Brighter than a tube.

[Brief description of drawings]

FIG. 1 is a graph illustrating the relationship between the amount of P contained in the phosphor used in the present invention and the emission brightness when the phosphor is excited by a low-speed electron beam. FIG. 2 is a bipolar electrode according to the present invention. FIG. 3 is a schematic view of the fluorescent display tube of FIG. 3, and FIG. 3 is a schematic view of a triode fluorescent display tube according to the present invention.

Continuation of the front page (56) References JP-A-62-86085 (JP, A) JP-B 31-68 (JP, B1) JP-B 32-9217 (JP, B1)

Claims (5)

[Claims] 1. A low-speed electron excitation fluorescent display tube having a structure in which an anode plate having a fluorescent film on one surface and a cathode facing the fluorescent film are enclosed in a container having a vacuum inside. General formula (Zn _1-X , Cdx) S: aM, bX, cP (where M is at least one of Cu, Ag and Au, and X is
At least one of F, Cl, Br, I and Al, wherein x, a, b and c are 0 ≦ x ≦ 1, 0 <a ≦ 5 × 10 ⁻³ g / g,
0 <b ≤ 10 ^-2 g / g and 0 <c ≤ 10 ^-2 g / g), and a P-containing sulfide-based phosphor represented by the formula A slow-electron-beam-excited fluorescent display tube characterized by comprising a luminescent material which is a mixture with an organic substance. 2. The low-speed electron beam excitation fluorescent display tube according to claim 1, wherein the M is Ag. 3. The claim 1 or 2 wherein the c value is a number satisfying the condition of 10 ⁻⁴ g / g ≦ c ≦ 5 × 10 ⁻³ g / g. Slow electron beam excitation fluorescent display tube. 4. The conductive material according to claim 1, wherein the conductive material is at least one of In ₂ O ₃ , ZnO and SnO _2. Slow electron beam excitation fluorescent display tube. 5. The low-speed electron beam excitation fluorescent display tube according to claim 4, wherein the conductive substance is In ₂ O ₃ .