JP3982667B2 - Slow electron beam excited phosphor and fluorescent display tube - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a phosphor that emits and emits light by a low-energy electron beam, and a fluorescent display tube that uses the phosphor, and more particularly, to a CaS phosphor that has improved luminance characteristics and a fluorescent display tube that uses the CaS phosphor.
[0002]
[Prior art]
Conventionally, a fluorescent display tube, which is one of electronic display devices, has been widely used as a display component for acoustic equipment and automobile dashboards. In this fluorescent display tube, an anode to which a phosphor is attached and a cathode at a position facing the anode are arranged in a vacuum vessel, and light emitted from the cathode is caused to collide with the phosphor. In general, a triode type in which a phosphor for selectively emitting light by providing a grid for controlling the flow of electrons between a cathode and an anode is used most often. The phosphor used in such a fluorescent display tube is a phosphor called a low-energy electron beam-excited phosphor, which can obtain a practical luminance with an acceleration voltage of about 100V.
[0003]
Incidentally, in recent years, with the expansion of applications of fluorescent display tubes, demand for multicolor display has increased. In the early days of flat fluorescent display tubes, there was no phosphor other than green-emitting ZnO: Zn as a phosphor capable of obtaining a practically sufficient luminance with a low-speed electron beam having an operating voltage of about 10 to 50V. However, indium oxide (In ₂ O _Three Since the development of technology for reducing the resistance of phosphors using conductive materials such as), multicolor light emission using sulfide phosphors has become possible. As such a phosphor, for example, blue light emitting ZnS: Cl + In ₂ O _Three , Yellow-green light emitting ZnS: Cu, Al + In ₂ O _Three , ZnCdS emitting red light: Ag, Cl + In ₂ O _Three and so on.
[0004]
[Problems to be solved by the invention]
However, in fluorescent display tubes using these sulfide phosphors, the sulfide phosphor is decomposed by electron beam irradiation, and the scattered sulfur (S) adheres to the cathode and degrades the oxide as the electron source material. And there is a problem of lowering the luminance. For this reason, a sulfide phosphor more stable than a ZnCdS phosphor or a ZnS phosphor with respect to electron beam irradiation has been demanded. A condition for a stable sulfide phosphor is that the melting point of the base sulfide is high. This is because the higher the melting point, the stronger the bond between atoms and the more stable the electron beam irradiation.
[0005]
As a sulfide phosphor having a melting point higher than that of a ZnCdS phosphor or a ZnS phosphor, a CaS phosphor based on calcium sulfide (CaS) is known. Since the melting point of CaS is 2000 ° C. or higher, it is considered to be more stable to electron beam irradiation than CdS having a melting point of about 1600 ° C. or ZnS that sublimes without melting. However, although the conventional CaS phosphors are excellent in luminous efficiency in a high voltage range, the emission intensity is low in a low-speed electron beam. For example, the relative luminance of a CaS: Eu phosphor emitting red light similarly emits red light. It was 1/4 or less of ZnCdS: Ag, Cl phosphor, and only about 1/2 of the luminance necessary for practical use was obtained.
[0006]
The present invention has been made in order to solve the above-described problems, and can provide a luminance necessary for practical use at a low acceleration voltage of about 100 V, and has an adverse effect on the cathode emission due to the decomposition of the phosphor. An object of the present invention is to provide a fluorescent display tube having a long lifetime with little reduction in luminance using the CaS phosphor and providing a few CaS phosphors.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present inventor has conducted various experiments to achieve the above-mentioned object with respect to the CaS: Eu phosphor. As a result, when doping calcium sulfide with europium, it is possible to simultaneously dope lithium with europium. It has been found that the emission intensity is stronger than when only doping is performed. It was also found that when europium is doped into calcium sulfide, the emission intensity is further enhanced by simultaneously doping lithium and chlorine. Further, it has been found that when these CaS phosphors are used for a phosphor film of a fluorescent display tube, light is emitted with practically sufficient luminance even when the excitation voltage is 26 V by mixing indium oxide. Further, in addition to europium, the inventors have found that the emission intensity is similarly increased with a rare earth element such as cerium, and the present invention has been achieved.
[0008]
The low-energy electron beam-excited phosphor of the present invention is characterized by being composed of one element selected from calcium, sulfur and rare earth elements and lithium. In one configuration example of this low-energy electron beam-excited phosphor, one kind of element selected from rare earth elements is composed of europium. In this case, each component element of the phosphor is desirably 1 mol of sulfur per 1 mol of calcium, and 0.0001 mol or more and 0.1 mol or less of europium and lithium, respectively.
[0009]
Another structural example of the low-energy electron beam-excited phosphor according to the present invention is characterized by comprising one kind of element selected from calcium, sulfur and rare earth elements, lithium and chlorine. In one configuration example of this low-energy electron beam-excited phosphor, one kind of element selected from rare earth elements is composed of europium. In this case, each component element of the phosphor is desirably 1 mol of sulfur per 1 mol of calcium and 0.0001 mol or more and 0.1 mol or less of europium, lithium and chlorine, respectively.
[0010]
The fluorescent display tube according to the present invention has an anode and a cathode on which a phosphor film is attached in a vacuum vessel, and emits light by colliding electrons emitted from the cathode with the phosphor film. The film is characterized by being composed of a mixture of the low-energy electron beam-excited phosphor and indium oxide described above. In the phosphor film of the fluorescent display tube described above, it is desirable that indium oxide is mixed in a range not exceeding 5 wt% and not exceeding 30 wt% with respect to the phosphor.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
In the low-energy electron beam-excited phosphor according to the first embodiment of the present invention, the phosphor matrix is calcium sulfide (CaS), and europium (Eu), which is one of rare earth elements, and an alkali metal are included in the phosphor matrix. One of the elements, lithium (Li), is doped. Hereinafter, this phosphor is referred to as a CaS: Eu, Li phosphor. In this embodiment, the addition amounts of Eu and Li were 0.001 mol per 1 mol of CaS.
[0012]
The CaS: Eu, Li phosphor is manufactured as follows.
First, 99.99% pure CaS and 99.9% pure Eu. ₂ O _Three And 99.9% pure Li ₂ CO _Three And Eu per mole of CaS ₂ O _Three And Li ₂ CO _Three Are weighed so that both are 0.0005 mol, and then mixed in an alumina mortar. Next, the mixed powder is put into an alumina crucible, heated to 1000 to 1300 ° C. in a nitrogen atmosphere, and fired for 1 to 4 hours. Thereby, a CaS: Eu, Li phosphor containing 0.001 mol of Eu and Li per mol of CaS is produced. Note that the atmosphere during firing is not limited to a nitrogen atmosphere, and may be an inert gas atmosphere such as argon, or a weakly reducing atmosphere such as a mixed gas of nitrogen and hydrogen.
[0013]
Next, FIG. 1 shows the result of comparing the luminance of the CaS: Eu, Li phosphor with that of the CaS: Eu phosphor and the ZnCdS: Ag, Cl phosphor. FIG. 1 is a graph showing the relative luminance of the CaS: Eu phosphor and the ZnCdS: Ag, Cl phosphor when the luminance of the CaS: Eu, Li phosphor is 100%. Here, the CaS: Eu, Li phosphor is one in which Eu and Li are each 0.001 mole per mole of CaS, and the CaS: Eu phosphor is one in which Eu is 0.001 mole per mole of CaS. is there. The CaS: Eu, Li phosphor and the CaS: Eu phosphor are excited by a low-energy electron beam and emit red light at a peak wavelength of 640 nm. In addition, ZnCdS: Ag, Cl phosphor is Zn emitting red light at a peak wavelength of 635 nm. _0.3 Cd _0.7 S: Ag, Cl was used.
[0014]
In FIG. 1, when the luminance of the CaS: Eu, Li phosphor is 100%, the relative luminance of the CaS: Eu phosphor is 33%, and the relative luminance of the ZnCdS: Ag, Cl phosphor is 176%. The brightness of the CaS: Eu, Li phosphors was improved to about 3 times that of the conventional CaS: Eu phosphors. Here, the luminance necessary for practical use is about 60% of the level shown in FIG. 1, and the CaS: Eu, Li phosphor of the present invention has a luminance exceeding this level. In addition, the brightness | luminance of these fluorescent substance is 20 wt%-25 wt% In. ₂ O _Three Are applied to the anode of the fluorescent display tube, and an anode voltage of +26 V is applied at a duty ratio of 1/16.
[0015]
Next, the luminance enhancement effect of the CaS-based phosphor due to the addition of lithium will be described using a CaS: Eu, Li phosphor as an example. When Li is added to the CaS: Eu phosphor, the conductivity of the base CaS is improved, so that the negative charge on the surface of the phosphor particles under electron beam excitation can be easily released, and the negative potential on the surface is reduced. Thereby, it is estimated that the substantial anode voltage applied to the phosphor is increased, the energy of the colliding electrons is increased, the excitation is facilitated, and the luminance is improved.
[0016]
Next, the addition amount of Eu and Li in the CaS: Eu, Li phosphor for obtaining the luminance necessary for practical use will be described. In order to obtain a luminance necessary for practical use, when the addition amount of Eu added to CaS is in the range of 0.0001 mol or more and 0.1 mol or less per 1 mol of CaS, the addition amount of Li is set to 0.000 per 1 mol of CaS. It is desirable to set it in the range of 0001 mol or more and 0.1 mol or less. Here, the lower limit of the addition amount of Li is set to 0.0001 mol or more per mole of CaS because the effect of improving the conductivity of the phosphor is small when the addition amount of Li is less than 0.0001 mol. This is because the luminance necessary for practical use may not be obtained depending on the amount.
[0017]
In addition, the upper limit of the Li addition amount is set to 0.1 mol or less per mole of CaS because the luminance decreases when the Li addition amount exceeds 0.1 mol, and depending on the Eu addition amount, the luminance that is practically required This is because may not be obtained. It is presumed that the brightness decreases when the amount of Li added is too large because the influence of lattice defects generated by the addition of Li increases. When the addition amount of Li is constant, the luminance is 20% or more higher when the addition amount of Eu is between 0.001 mol and 0.01 mol than in the vicinity of 0.0001 mol or near 0.1 mol. Therefore, even when the amount of Li added is less than 0.0001 mol or more than 0.1 mol, there may be a case where luminance necessary for practical use can be obtained. For this reason, when the addition amount of Eu is between 0.001 mol and 0.01 mol, the range of the addition amount of Li can be expanded.
[0018]
Further, when the addition amount of Eu is constant, when the addition amount of Li is between 0.001 mol and 0.01 mol, the luminance is 10% or more higher than that near 0.0001 mol or near 0.1 mol. Therefore, even when the amount of Eu added is less than 0.0001 mol or more than 0.1 mol, a luminance necessary for practical use may be obtained. For this reason, when the addition amount of Li is between 0.001 mol and 0.01 mol, the range of the addition amount of Eu can be expanded. In order to further improve the luminance, it is desirable that the addition amount of Eu is 0.001 mol to 0.01 mol and the addition amount of Li is 0.001 mol to 0.01 mol.
[0019]
In this embodiment, the CaS: Eu, Li phosphor has been described as an example. However, the present invention is not limited to this. For example, a CaS: Ce phosphor using a rare earth element cerium (Ce) as the emission center. It is also possible to apply to a phosphor emitting yellow-green light to obtain a CaS: Ce, Li phosphor. Further, the present invention can also be applied to other phosphors having CaS as a base material and a rare earth element as an emission center.
[0020]
Next explained is the second embodiment of the invention.
In the low-energy electron beam-excited phosphor according to the second embodiment of the present invention, the phosphor matrix is calcium sulfide (CaS), and europium (Eu), which is one of rare earth elements, and an alkali metal are included in the phosphor matrix. Lithium (Li) which is one of elements and chlorine (Cl) which is one of halogen elements are doped. Hereinafter, this phosphor is referred to as a CaS: Eu, Li, Cl phosphor. The CaS: Eu, Li, Cl phosphor has a further improved luminance as compared with the CaS: Eu, Li phosphor shown in the first embodiment. In this embodiment, the addition amount of Eu, Li, and Cl is 0.001 mol per 1 mol of CaS.
[0021]
The CaS: Eu, Li, Cl phosphor is manufactured as follows.
First, 99.99% pure CaS and 99.9% pure Eu. ₂ O _Three And 99.9% pure Li ₂ CO _Three And NH _Four Cl, Eu per mole of CaS ₂ O _Three And Li ₂ CO _Three Both became 0.0005 mol, NH _Four Weigh each so that Cl becomes 0.001 mol, and then put it in an alumina mortar and mix thoroughly. Next, the mixed powder is put into an alumina crucible, heated to 1000 to 1300 ° C. in a nitrogen atmosphere, and fired for 1 to 4 hours. As a result, a CaS: Eu, Li, Cl phosphor containing 0.001 mol of Eu, Li, and Cl per mol of CaS is produced. Note that the atmosphere during firing is not limited to a nitrogen atmosphere, and may be an inert gas atmosphere such as argon, or a weakly reducing atmosphere such as a mixed gas of nitrogen and hydrogen.
[0022]
Here, the Cl source is NH _Four Not limited to Cl, chlorides of alkali metal elements (NaCl, KCl, RbCl, CsCl) and chlorides of alkaline earth metal elements (MgCl ₂ , CaCl ₂ , SrCl ₂ , BaCl ₂ ) Can also be used. In this manufacturing method, since the Eu source, the Li source, and the Cl source are added as separate compounds, the Eu concentration, the Li concentration, and the Cl concentration in the CaS: Eu, Li, Cl phosphor can be independently changed. The optimum concentration can be selected depending on the use conditions.
[0023]
Next, FIG. 2 shows the result of comparing the luminance of the CaS: Eu, Li, Cl phosphor with that of the CaS: Eu phosphor and the CaS: Eu, Li phosphor. FIG. 2 is a graph showing the relative luminance of the CaS: Eu phosphor and the CaS: Eu, Li, Cl phosphor when the luminance of the CaS: Eu, Li phosphor is 100%. Here, the CaS: Eu, Li, Cl phosphor is one in which Eu, Li, and Cl are each 0.001 mole per mole of CaS, and the CaS: Eu, Li phosphor is Eu and Li per mole of CaS. In each case 0.001 mol. In addition, the CaS: Eu phosphor has a Eu content of 0.001 mol per mol of CaS.
[0024]
The luminance of these phosphors is 20 wt% to 25 wt% In. ₂ O _Three Were mixed and applied to the anode of a fluorescent display tube, and an excitation voltage of +26 V was applied to the anode at a duty ratio of 1/16 and measured. In FIG. 2, when the luminance of the CaS: Eu, Li phosphor is 100%, the relative luminance of the CaS: Eu, Li, Cl phosphor is 117%, and the relative luminance of the CaS: Eu phosphor is 33%. It can be seen that the brightness of the CaS: Eu, Li, Cl phosphor of this embodiment is improved by 17% compared to the CaS: Eu, Li phosphor.
[0025]
Next, the luminance improvement effect by adding chlorine will be described by taking a CaS: Eu, Li, Cl phosphor as an example. The mechanism of luminance improvement by addition of chlorine has not been clarified yet, but Eu is added to Cl in CaS with a +2 valence (Eu ²⁺ ) Is presumed to have a stabilizing effect. Eu is +2 in CaS (Eu ²⁺ ) Emits red light, but Eu takes +2 and +3 valence states, so doped Eu is Eu. ²⁺ And Eu ³⁺ Therefore, the luminous efficiency is poor and the luminance is low. When doping Ca to be the base material with Eu as the emission center and simultaneously doping with Cl, Eu ²⁺ It is considered that the ratio of the light emission increases, the luminous efficiency is improved, and the luminance is improved.
[0026]
Next, the addition amounts of Eu, Li, and Cl in the CaS: Eu, Li, Cl phosphor will be described. This CaS: Eu, Li, Cl phosphor is obtained by improving the luminance of the CaS: Eu, Li phosphor shown in the first embodiment, and the addition amount of Eu and Li is 0 per mol of CaS, respectively. When it is in the range of 0.0001 mol or more and 0.1 mol or less, the addition amount of Cl is preferably in the range of 0.0001 mol or more and 0.1 mol or less per mol of CaS. Here, the reason why the lower limit of the addition amount of Cl is set to 0.0001 mol or more per 1 mol of CaS is that luminance is improved when the addition amount of Cl is 0.0001 mol or more. The upper limit of the amount of Cl added is set to 0.1 mol or less because when the amount of added Cl exceeds 0.1 mol, deterioration of the filamentous oxide cathode used in the fluorescent display tube due to Cl increases. It is.
[0027]
Similarly to the CaS: Eu, Li phosphor, the CaS: Eu, Li, Cl phosphor also has a Eu addition amount of 0.001 mol to 0.01 mol when the addition amount of Li and Cl is constant. In the meantime, the luminance is increased by 20% or more compared with around 0.0001 mol and around 0.1 mol. In addition, when the addition amount of Eu and Cl is constant, the luminance is 10% when the addition amount of Li is between 0.001 mol and 0.01 mol compared with around 0.0001 mol and near 0.1 mol. More than that. Therefore, in order to further improve the luminance, it is desirable that the addition amount of Eu is 0.001 mol to 0.01 mol and the addition amount of Li is 0.001 mol to 0.01 mol.
[0028]
In this embodiment, the above-described Eu is used as a method for producing a CaS: Eu, Li, Cl phosphor. ₂ O _Three And Li ₂ CO _Three And NH _Four Although the method using Cl has been described, the present invention is not limited to this. Eu ₂ O _Three And LiCl may be used. In this case, Eu per mol of CaS ₂ O _Three Is 0.0005 mol and LiCl is 0.001 mol, and then weighed in an alumina mortar and mixed well. Next, the mixed powder was put in an alumina crucible and 1000-1300 in a nitrogen atmosphere. Bake for 1 to 4 hours by heating to ℃. As a result, a CaS: Eu, Li, Cl phosphor containing 0.001 mol of Eu, Li, and Cl per mol of CaS is produced. According to this manufacturing method, the ratio of Li to Cl is fixed to 1: 1, but there is an effect that the LI source and the Cl source need not be prepared separately, and the procedure can be simplified.
[0029]
In this embodiment, the CaS: Eu, Li, Cl phosphor has been described as an example. However, the present invention is not limited to this. For example, the present invention is applied to a CaS: Ce, Li phosphor that emits yellow-green light. , Li, Cl phosphors may be used. In the case of Ce, the valence is +3 or +4, but Ce is +3 in CaS (Ce ³⁺ ) Emits yellow-green light, and Cl is converted to Ce +3 valence (Ce by the same mechanism as Eu). ³⁺ ) Is considered to be stabilized. Further, the present invention can also be applied to other phosphors having CaS as a base material and a rare earth element as an emission center.
[0030]
Next, an embodiment of a fluorescent display tube using the low-energy electron beam-excited phosphor of the present invention will be described. FIG. 3 shows a configuration of the fluorescent display tube according to this embodiment. In this fluorescent display tube, a wiring layer 2 having a predetermined pattern is formed on a glass substrate 1, and a through layer is formed on the wiring layer 2. An insulating layer 3 having holes 3a is formed. On the surface of the insulating layer 3, an anode 4 having a predetermined pattern, which is conductively connected to the wiring layer 2 through the through hole 3a, is formed. On the anode 4, a CaS: Eu, Li, Cl phosphor and indium oxide ( In ₂ O _Three ) Is mixed and formed.
[0031]
A grid 6 is disposed above the phosphor film 5, and a filamentous oxide cathode 7 in which (Ba, Sr, Ca) O is coated on a thin tungsten wire is disposed above the grid 6. A translucent face glass 9 is disposed above the filamentary oxide cathode 7 and is held at a predetermined distance from the glass substrate 1 by a frame-like side wall 8. The glass substrate 1, the side wall 8, and the face glass 9 are sealed with a frit glass 10 having a low melting point to form a vacuum container 10. ^-3 -10 ^-Five The vacuum is maintained at Pa. A plurality of leads (not shown) are provided through the contact portion between the side wall 8 and the glass substrate 1, and an electrical signal is applied from the outside to the cathode 7, the grid 6, and the anode 4 described above. ing.
[0032]
Here, the method of depositing and forming the phosphor film 5 on the anode 4 may be the same as the conventional manufacturing method, and the CaS: Eu, Li, Cl phosphor and In ₂ O _Three The phosphor paste obtained by mixing with a suitable organic binder is screen-printed on the anode 4 and then heated and baked at about 500 ° C. in the air to decompose the organic binder present in the phosphor film 5. Let it form. Thereby, CaS: Eu, Li, Cl phosphor and In ₂ O _Three Is formed on the anode 4. When the organic binder decomposes during the firing process, ₂ Or since it burns as CO, the ambient atmosphere is neutral or reducible, so that oxidation of the phosphor can be suppressed. Therefore, when using a phosphor that easily deteriorates due to oxidation, such as CaS, it is desirable to increase the amount of the organic binder in the phosphor paste.
[0033]
In this case, the addition amounts of Eu, Li, and Cl in the CaS: Eu, Li, Cl phosphor were 0.001 mol of Eu, Li, and Cl, respectively, per 1 mol of CaS. Also, In ₂ O _Three The addition ratio of was set to a range of 20 wt% to 25 wt% with respect to the phosphor. In ₂ O _Three As shown in FIG. 4, since the luminance decreases by 20% or more in the region of less than 5 wt% and in the region of more than 30 wt%, it is desirable that the mixing amount be in the range of 5 wt% or more and 30 wt% or less. Is 18 wt% to 25 wt% at which the luminance is maximized. The luminance decreases because the conductivity of the entire phosphor screen is insufficient in the region of less than 5 wt%, and In is a non-light emitting material in the region of more than 30 wt%. ₂ O _Three This is probably because the ratio of In addition, since the manufacturing method of this fluorescent display tube is the same as a well-known fluorescent display tube, description is abbreviate | omitted.
[0034]
In the fluorescent display tube of this embodiment, the CaS: Eu, Li, Cl phosphor has been described as an example of the phosphor used for the phosphor film. However, the present invention is not limited to this, and the aforementioned CaS: Eu, Li fluorescence is used. Body, CaS: Ce, Li, Cl phosphor, CaS: Ce, Li phosphor, other phosphors containing Ca and Li and Cl and rare earth elements as emission centers, and Ca containing Li added Other phosphors having a rare earth element as the emission center can be used in the same manner.
[0035]
Next, FIG. 5 shows the result of comparing the luminance characteristics of the CaS: Eu, Li, Cl phosphor and the CaS: Eu, Li phosphor using the fluorescent display tube of this embodiment. FIG. 5 is a graph showing the relative luminance of the CaS: Eu, Li phosphor when the luminance at an excitation voltage of 100 V of the CaS: Eu, Li, Cl phosphor is 100%, and CaS: Eu, Li, Cl fluorescence. The body is shown in (a), and the CaS: Eu, Li phosphor is shown in (b). Here, the CaS: Eu, Li, Cl phosphor is one in which Eu, Li, and Cl are each 0.001 mole per mole of CaS, and the CaS: Eu, Li phosphor is Eu and Li per mole of CaS. In each case 0.001 mol. In addition, the brightness | luminance of these fluorescent substance is 20 wt%-25 wt% In. ₂ O _Three Were mixed and applied to the anode of the fluorescent display tube, and an excitation voltage was applied to the anode at a duty ratio of 1/12.
[0036]
In FIG. 5, when the luminance of the CaS: Eu, Li, Cl phosphor at an excitation voltage of 100 V is 100%, the relative luminance of the CaS: Eu, Li phosphor is 85%, and the CaS: Eu, Li from the start of light emission. , The brightness of the Cl phosphor exceeds the brightness of the CaS: Eu, Li phosphor, indicating that the addition of Cl is effective. Thus, the CaS: Eu, Li, Cl phosphor has an effect that the luminance can be increased as compared with the CaS: Eu, Li phosphor. On the other hand, the CaS: Eu, Li phosphor has lower luminance than the CaS: Eu, Li, Cl phosphor, but has no advantage of deteriorating the oxide cathode because it does not contain Cl. It is good to use properly according to.
[0037]
Further, although the embodiment of the fluorescent display tube of the present invention has been described with the fluorescent display tube having a structure in which the light emission of the phosphor film 5 as shown in FIG. 3 is observed through the translucent face glass 9, the present invention is not limited to this. As long as the phosphor film 5 contains the phosphor according to the present invention, the other structure may be the same as that of a known fluorescent display tube.
[0038]
【The invention's effect】
As described above, the low-energy electron beam-excited phosphor of the present invention is selected from conventional calcium sulfide and rare earth elements because it is composed of lithium, one kind of element selected from calcium, sulfur and rare earth elements. In addition, it has an effect that a luminance higher than that of a phosphor composed of one kind of element can be obtained. In addition, another low-energy electron beam-excited phosphor of the present invention is composed of one element selected from calcium, sulfur, and rare earth elements, lithium, and chlorine, so that the luminance can be further improved. There is. In addition, since the fluorescent display tube of the present invention is provided with the phosphor film in which the low-energy electron beam-excited phosphor and indium oxide described above are mixed, the luminance necessary for practical use can be obtained at a low acceleration voltage, There is little adverse effect on the cathode emission due to the decomposition of the body, and it has the effect of extending the life.
[Brief description of the drawings]
FIG. 1 is a graph comparing the luminance of a phosphor according to a first embodiment and a conventional phosphor.
FIG. 2 is a graph comparing the luminance of the phosphor according to the second embodiment and the phosphor according to the first embodiment.
FIG. 3 is a cross-sectional view showing a configuration of an embodiment of a fluorescent display tube according to the present invention.
FIG. 4 shows a fluorescent display tube In according to the present invention. ₂ O _Three It is a graph which shows the change of the brightness | luminance by the difference in addition amount.
FIG. 5 is a graph showing the relationship between excitation voltage and luminance of a fluorescent display tube according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Glass substrate, 2 ... Wiring layer, 3 ... Insulating layer, 3a ... Through hole, 4 ... Anode, 5 ... Phosphor film, 6 ... Grid, 7 ... Cathode, 8 ... Side wall, 9 ... Face glass, 10 ... Frit Glass.

Claims (8)

A low-energy electron beam-excited phosphor comprising a single element selected from calcium, sulfur and rare earth elements and lithium. The low-energy electron beam-excited phosphor according to claim 1, wherein one element selected from the rare earth elements is europium. The sulfur is 1 mol per 1 mol of the calcium, the europium is 0.0001 mol or more and 0.1 mol or less, and the lithium is 0.0001 mol or more and 0.1 mol or less. The low-energy electron beam-excited phosphor according to claim 2. A low-energy electron beam-excited phosphor comprising a single element selected from calcium, sulfur and rare earth elements, lithium and chlorine. The low-energy electron beam-excited phosphor according to claim 4, wherein one element selected from the rare earth elements is europium. The sulfur is 1 mole, the europium is 0.0001 mole or more and 0.1 mole or less, the lithium is 0.0001 mole or more and 0.1 mole or less, and the chlorine is 0 mole per mole of the calcium. The low-energy electron beam-excited phosphor according to claim 5, wherein the amount is 0.0001 mol or more and 0.1 mol or less. In a vacuum vessel, an anode and a cathode to which a phosphor film is attached are installed, and in a fluorescent display tube that emits light by colliding electrons emitted from the cathode with the phosphor film,
A fluorescent display tube, wherein the phosphor film is composed of a mixture of a low-energy electron beam-excited phosphor according to any one of claims 1 to 6 and indium oxide. 8. The fluorescent display tube according to claim 7, wherein the indium oxide is mixed in a range of 5 wt% to 30 wt% with respect to the low-energy electron beam excited phosphor.

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