JP2006140001A - Fluorescent display tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluorescent display tube using a new oxynitride phosphor not containing Cd as an environmental load substance.
A phosphor layer 20 in which conductive fine particles such as In ₂ O ₃ containing Ca, Si, N, and Eu as a light emission center are mixed on an anode conductor 11 of a glass substrate 10 constituting a fluorescent display tube. And a ZnO: Zn phosphor layer 30 is provided thereon. Light emitted in the range of 400 nm to 550 nm from the phosphor layer 30 emitted by the electron impact is efficiently converted into yellow to red light in the range of 560 nm to 680 nm by the phosphor layer 20 and irradiated through the glass substrate. . If these two phosphors are appropriately mixed, light emission such as red, orange, yellow, and white can be selected depending on the mixing ratio. Due to the mixing of the conductive fine particles, the phosphor layer is hardly peeled off from the glass substrate.
[Selection] Figure 3

Description

  The present invention relates to a fluorescent display tube having a phosphor layer that receives electrons emitted from an electron source disposed in a vacuum-tight container and emits light with high brightness in white or yellow to red warm colors. In particular, the present invention relates to a fluorescent display tube which is Cd-free, has a low environmental load, and has better life characteristics and light emission characteristics than conventional ones.

  Various phosphors are used in the fluorescent display tube in order to obtain each emission color. In these fluorescent display tubes, white light emission that is versatile, especially for use in backlights, is strongly demanded, and on the other hand, yellow to red warm colors are important for increasing variations in the use of fluorescent display tubes. There is a strong demand for something.

  In order to realize such white light emission and warm color light emission, various attempts have been conventionally made, but the results are not always satisfactory.

  For example, a technology relating to a fluorescent display tube that emits white light by forming a phosphor layer in which a phosphor that emits yellow to red light and a phosphor such as ZnO: Zn phosphor that emits green to blue light, for example, is known. It has been. However, since the voltage dependence of the luminance of the phosphor differs depending on the type, there is a problem that a color shift occurs, which is a phenomenon in which the emission color changes due to a change in driving voltage.

  In addition, there is a technique in which an ultraviolet-emitting oxide phosphor is stacked on the upper surface of a phosphor layer containing a ZnS: Zn-based blue-emitting phosphor or other visible light-emitting phosphor, and the transmitted light excited by the ultraviolet light is observed. It is disclosed. However, there is no phosphor that has an excellent lifetime characteristic as an electron beam-excited ultraviolet light-emitting phosphor, particularly for fluorescent display tubes.

  Further, a phosphor layer containing a non-sulfide phosphor that emits light by low-energy electron beam excitation is laminated on the upper surface of the phosphor layer containing ZnCdS: Ag, Cl red light-emitting sulfide phosphor, and the non-sulfide phosphor becomes an electron. A technique for emitting red light by reducing the decomposition of the ZnCdS: Ag, Cl phosphor by emitting light from the phosphor layer containing the ZnCdS: Ag, Cl phosphor by a short wavelength component that emits light upon receiving a line is known. It has been. However, when the ZnCdS: Ag, Cl and the ZnO: Zn slow electron beam-excited phosphor are combined, there are many portions where the absorption of ZnCdS: Ag, Cl is shifted from the emission of ZnO: Zn, so that pure red light emission occurs. Cannot be obtained. Moreover, above all, there is a problem that Cd is an environmentally hazardous substance.

  That is, according to the ZnCdS: Ag phosphor, yellow to red warm-colored luminescence can be obtained, but Cd as a component of this phosphor is an environmentally hazardous substance. There is a strong demand for Cd reduction from phosphor components, and the current situation is that Cd-free is a requirement of the times.

As the Cd-free phosphor, SrTiO ₃ : Pr phosphor and Ln ₂ O ₂ S: Eu phosphor have been developed and partially put into practical use. However, the lifetime characteristics of the SrTiO ₃ : Pr phosphor and Ln ₂ O ₂ S: Eu phosphor are inferior to those of the blue-green light emitting ZnO: Zn phosphor generally used for fluorescent display tubes. However, it is difficult to use together with a ZnO: Zn phosphor having a stable lifetime.

Patent Documents 1 to 3 have recently disclosed oxynitride phosphors commonly called sialon phosphors. This sialon phosphor is attracting attention as a yellow to red component light-emitting phosphor of a white LED, and realizes a high-intensity white LED using the light emission (450 to 500 nm) of a blue LED as excitation light. It is a substance used as fluorescent glass and is not assumed to be used as a fluorescent substance for fluorescent display tubes that emit light when irradiated with an electron beam. The composition disclosed in this document is a fluorescent display. It cannot be effective when applied to a tube.
Non-Patent Document 1 describes Ca ₂ Si ₅ N ₈ : Eu.
Non-Patent Document 2 describes a CaAlSiN ₃ phosphor.
JP 2001-214162 A JP 2002-363554 A JP 2003-336059 A Joost Willem Hendrik van Krevel, “On new rare-earth doped M-Si-ON materials”, ISBN 90-386. -2711-4, 2000, p. 31 Naoto Hirosaki and 6 others, “Synthesis and Crystal Structure of Red Nitride Phosphor (CaAlSiN 3: Eu 2+)”, Proc. 3, lecture number 2p-XL-12, p. 1283

  The inventors of the present application realize a fluorescent display tube capable of obtaining white light emission or yellow to red warm color light emission by using an oxynitride phosphor commonly referred to as a sialon phosphor described in Patent Documents 1 to 3. Efforts have been made as much as possible, but the matching of the emission wavelength with other phosphors used in combination is not appropriate, and the adhesion strength when applied to a glass substrate or the like and firing is insufficient, resulting in peeling. Many problems have been discovered regarding the basic performance required for practical use as a phosphor of the above-mentioned phosphors, and the phosphors described in Patent Documents 1 to 3 are used as they are in white light emission and yellow to red warm colors in a fluorescent display tube. It was concluded that it cannot be adopted as a phosphor for obtaining the light emission.

  Therefore, the present invention has been proposed based on the above-described prior art, and is Cd-free and fluorescent display in realizing a fluorescent display tube capable of obtaining white light emission or warm light emission of yellow to red. Since it has resistance to the gas in the tube, it has good life characteristics, the above-mentioned luminescent color can be realized with high luminance, there is little color change over time, and luminance unevenness is less likely to occur. An object of the present invention is to provide a fluorescent display tube provided with a phosphor layer that has good adhesion to an insulating substrate and that does not easily peel off.

  In particular, the highly reliable ZnO: Zn blue-green light emission can be efficiently color-converted to realize the light emission color with high luminance, and there is little color change over time, and luminance unevenness hardly occurs. It is a further object to provide a fluorescent display tube provided with a phosphor layer containing a phosphor that has good adhesion to the insulating substrate constituting the vacuum hermetic vessel of the tube and is difficult to peel off.

  In order to achieve the above object, the present invention optimizes the composition of the above-described oxynitride phosphor (sialon phosphor) and thereby uses white phosphor in combination with a phosphor such as ZnO: Zn. Further, it is intended to make it possible to obtain light emission of warm colors of yellow to red, and to realize these emission colors as a phosphor for a fluorescent display tube alone.

The fluorescent display tube according to claim 1 includes a vacuum hermetic container, an electron source disposed in the vacuum hermetic container, an anode disposed on an inner surface of an insulating substrate constituting the vacuum hermetic container, In a fluorescent display tube having a phosphor layer that is formed on the anode and emits light by a projection of electrons emitted from the electron source,
The phosphor layer has a first phosphor having an emission peak wavelength in the range of 400 nm to 550 nm, and a second fluorescence emitting light having an emission peak in the range of 560 nm to 680 nm when excited by visible light of 450 nm to 550 nm. And a conductive fine particle for bringing the phosphor layer into close contact with the anode and imparting conductivity to the phosphor layer.

The fluorescent display tube according to claim 2 is the fluorescent display tube according to claim 1, wherein the phosphor layer is a second phosphor layer in which the second phosphor is laminated on the anode. And a first phosphor layer formed by laminating the first phosphor on the second phosphor layer,
Upon receiving the electron impact, the first phosphor layer emits light, and the second phosphor layer is excited by the light to emit light, and light from the second phosphor layer is translucent. Irradiation is performed outside the vacuum hermetic container through the insulating substrate and the light-transmitting anode.

  According to a third aspect of the present invention, in the fluorescent display tube according to the second aspect, the conductive fine particles are dispersed in the second phosphor layer.

  According to a fourth aspect of the present invention, in the fluorescent display tube according to the first aspect, the phosphor layer is a mixture of the first phosphor, the second phosphor, and the conductive fine particles. It is characterized by being configured.

  The fluorescent display tube according to claim 5 is the fluorescent display tube according to claim 4, wherein a mixing weight ratio of the first phosphor and the second phosphor is 0.01 to 0.7 pairs. It is characterized by 1.

  A fluorescent display tube according to claim 6 is the fluorescent display tube according to any one of claims 1 to 5, wherein the second phosphor is at least an alkaline earth element (Mg, Ca, Sr or Ba). It is characterized by containing Si, N, and Eu as the emission center.

  According to a seventh aspect of the present invention, in the fluorescent display tube according to the sixth aspect, the alkaline earth element is Ca.

The fluorescent display tube according to claim 8 is the fluorescent display tube according to any one of claims 1 to 5, wherein the second phosphor is Ca ₂ Si ₅ N ₈ activated with Eu. It is a feature.

  The fluorescent display tube described in claim 9 is the fluorescent display tube according to claim 1 to 5, wherein the second phosphor is Ca-α-sialon in which Eu is inactivated. It is said.

A fluorescent display tube according to a tenth aspect is the fluorescent display tube according to the first to fifth aspects, wherein the second phosphor is CaSiAlN ₃ in which Eu is inactivated.

The fluorescent display tube according to claim 11 is the fluorescent display tube according to any one of claims 1 to 10, wherein the first phosphor is made of ZnO: Zn, ZnS: Zn, ZnS: Ag or ZnGa ₂ O. It is characterized by being at least one phosphor selected from the group consisting of ₄ .

The fluorescent display tube according to claim 12 is the fluorescent display tube according to any of claims 1 to 11, wherein the conductive fine particles are selected from In ₂ O ₃ , ZnO, SnO ₂ , In, Zn, and Sn. It is characterized by being at least one kind of metal oxide and / or metal.

  A fluorescent display tube according to claim 13 is the fluorescent display tube according to claim 1 to 12, wherein the amount of the conductive fine particles is 1 wt% to 40 wt% with respect to the phosphor. It is said.

The fluorescent display tube according to claim 14,
A vacuum hermetic container; an electron source disposed in the vacuum hermetic container; an anode disposed on an inner surface of an insulating substrate constituting the vacuum hermetic container; and the electron source formed on the anode. In a fluorescent display tube having a phosphor layer that emits light due to a collision of electrons emitted from
The phosphor layer includes Ca, Si, N, and Eu as an emission center, and is formed on the upper surface of the anode and is excited by electrons emitted from the electron source to emit yellow to red light, and It is characterized by containing conductive fine particles that are mixed with a phosphor to bring the phosphor layer into close contact with the anode and impart conductivity to the phosphor layer.

  The phosphor layer of the fluorescent display tube is excited by visible light of 450 nm to 550 nm with a first phosphor having an emission peak wavelength in the range of 400 nm to 550 nm (for example, ZnO: Zn) and emits light in the range of 560 nm to 680 nm. If a second phosphor that emits light having a peak (for example, a so-called sialon phosphor containing at least Ca, Si, N, and Eu as a light emission center) and conductive fine particles added to these phosphors are used, Since it is possible to obtain a warm color from white or yellow to red by efficient color conversion using the light emission of the first phosphor having high brightness and high luminance, the luminance does not change with time and luminance unevenness is high. Stable and multicolor display is possible because it is difficult to occur and color change is difficult to occur. Furthermore, it has strong resistance against the residual gas in the fluorescent display tube, and the fluorescent display tube is an airtight container. Adhesion to the insulating substrate which constitutes also possible to provide a fluorescent display tube of good peeling difficult life with a phosphor layer.

  Further, a phosphor that emits light in the range of 560 nm to 680 nm (yellow to red range) when excited by an electron impact, for example, a so-called sialon phosphor containing Ca, Si, N, and Eu as a light emission center, is electrically conductive. If a phosphor layer is formed by mixing fluorescent fine particles, it has resistance to residual gas in the fluorescent display tube, so that it does not cause luminance unevenness and color change due to high luminance and little change in luminance over time. Therefore, it is a long-lived phosphor layer that can display multicolors and can stably produce a warm color from yellow to red, and further has adhesiveness to the insulating substrate constituting the hermetic container of the fluorescent display tube. A fluorescent display tube having a phosphor layer that is good and difficult to peel off can be provided.

1. The phosphor used in the embodiment of the present invention The second phosphor that emits light having an emission peak in the range of 560 nm to 680 nm excited by visible light of 450 nm to 550 nm described in claim 1 of the present application, and the present application The phosphor described in Item 13 containing Ca, Si, N, and Eu as an emission center and excited and emitted from yellow to red by an electron projecting point points to substantially the same substance, which is Cd-free. It is a phosphor in which the composition of the above-described conventional oxynitride phosphor (commonly referred to as a sialon phosphor) is optimized in accordance with the purpose and use of the present invention (hereinafter referred to as the purpose and use of the present invention). The oxynitride phosphor optimized in this manner is also referred to as “sialon phosphor” as appropriate).

  Therefore, in the following description or the description in the drawings, the names of the phosphors optimized for the fluorescent display tube according to the present invention are referred to as “phosphor” according to the present invention and “oxynitride phosphor” according to the present invention. For the sake of convenience, the name of “sialon”, which is a common name of the conventional oxynitride phosphor before improvement, may be used for improvement (or of the present invention).

Hereinafter, the process by which the present inventor has obtained an oxynitride phosphor optimized for the application and purpose of the present invention will be described.
First, as currently known Cd-free phosphors, there are Ln ₂ O ₂ S: Eu, SrTiO ₃ : Pr phosphors and other oxide phosphors as described in the section of the prior art. According to the findings, these oxide phosphors have a larger ionic radius of oxygen as a constituent element than that of metal elements, and thus the surface of the phosphor has polarity, so that the residual gas inside the fluorescent display tube, especially polarity, has polarity. Easy to adsorb moisture. The present inventors considered that this is the greatest cause of shortening the device life when these phosphors are used in a fluorescent display tube.

  Therefore, based on such consideration, the present inventor manufactures and uses a new oxynitride phosphor for a fluorescent display tube, which is an improvement of the above-described oxynitride phosphor (commonly referred to as a sialon phosphor) as a new Cd-free phosphor. As a result of a specific examination of the technical aspects of its feasibility, and through trial and error experiments, an acid having a specific composition optimized for the structure of a fluorescent display tube as described below. It came to devise the structure of the fluorescent substance layer containing nitride fluorescent substance.

  In this way, when the composition is optimized for the structure of the fluorescent display tube, a preferable technical action is achieved, such as the polarity of the surface being further reduced. In terms of emission color and emission luminance, a favorable effect can be obtained as a fluorescent display tube which cannot be expected from a conventional simple oxynitride phosphor.

In addition, the lifetime characteristics and the like are much improved compared to the aforementioned SrTiO ₃ : Pr phosphor and Ln ₂ O ₂ S: Eu phosphor, which are resistant to the gas in the fluorescent display tube. This is probably because of this. Therefore, as shown in Examples described later, it can be used in combination with the above-described ZnO: Zn phosphors that emit blue-green light generally used in fluorescent display tubes, and compared with these ZnO: Zn phosphors. Have the same life characteristics.

  This effect is achieved by the above-described oxynitride phosphor according to the present invention (1) “Efficient color conversion characteristics suitable for the emission wavelength of Zn-based phosphors frequently used in fluorescent display tubes”, (2) “Fluorescence display” This is considered to be due to “resistance to heat treatment in the manufacturing process of the tube”.

  However, the oxynitride phosphor according to the present invention has been clarified by further research by the inventor of the present application that the adhesion to a glass substrate or the like is low as it is, and if a countermeasure is not taken, the phosphor of the fluorescent display tube It is difficult to use as a phosphor having high adhesion to a glass substrate or the like used for the layer.

  Therefore, the present invention also realizes the property of high adhesion to a glass substrate or the like that can be used for such a fluorescent display tube. In the following description, the preferable characteristics (1) to (2) are described. In addition, reference is also made to (3) “adhesiveness to a glass substrate”.

(1) Color conversion characteristics suitable for a fluorescent display tube The phosphor contains at least Ca, Si, N and Eu as a light emission center, and can emit light from yellow to red depending on the ratio of these constituent elements. The excitation wavelength (absorption wavelength) of PL (photoluminescence) of the phosphor is generally in the range of 400 nm to 600 nm. The excitation wavelength distribution and emission wavelength distribution of the phosphors (1) and (2) are shown in FIG. 1 together with the emission wavelength distribution of the ZnO: Zn phosphor.

As shown in FIG. 1, the phosphor (1) (sialon red) emitting red light represented by Ca _0.992 SiAlN ₈ : Eu ^0.008 absorbs light having an excitation wavelength distribution (excitation, (a)) of 380 nm to 600 nm. And emits light with an emission wavelength component (emission, (A)) of 600 nm to 700 nm.

Ca _1.4 Si _8.08625 Al _31.375 O _0.1125 N _15.8875 : The phosphor (2) (sialon yellow) emitting yellow light represented by Eu ^0.075 absorbs light having an excitation wavelength distribution (excitation, (b)) of 380 nm to 580 nm. It is excited and emits light with an emission wavelength distribution (emission, (B)) of 550 nm to 650 nm.

  In contrast, the ZnO: Zn phosphor (C) has an emission peak at 505 nm and a main emission wavelength distribution (C) at 450 nm to 550 nm.

As is clear from this example, the present invention as exemplified in phosphor (1) (Ca _0.992 SiAlN ₈ : Eu ^0.008 ) and phosphor (2) (Ca _1.4 Si _8.08625 Al _31.375 O _0.1125 N _15.8875 : Eu ^0.075 ). The oxynitride phosphor (a phosphor containing Ca, Si, Al, N and Eu as a light emission center) has an absorption region (excitation region) in the light emission region of ZnO: Zn, and ZnO: Zn The light in this range can be efficiently absorbed and converted into red to yellow light emission.

(2) Resistance to heat treatment in the manufacturing process of the fluorescent display tube Further, phosphor (1) (Ca _0.992 SiAlN ₈ : Eu ^0.008 ) and phosphor (2) (Ca _1.4 Si _8.08625 Al _31.375 O _0.1125 N _15.8875 : Eu ^0.075 ) The oxynitride phosphor (phosphor containing Ca, Si, Al, N and Eu as the light emission center) according to the present invention as exemplified in FIG. Even after the heat treatment step at about 500 ° C., the PL intensity was not changed.

(3) Adhesiveness of the oxynitride phosphor according to the present invention to a glass substrate, etc. Next, an example in which the oxynitride phosphor of the present invention is mounted as a phosphor layer on a light emitting portion of a fluorescent display tube will be given. The adhesion to the substrate as a phosphor layer was examined.
First, as an example of the phosphor, a phosphor emitting red light represented by the phosphor (1) (Ca _0.992 SiAlN ₈ : Eu ^0.008 ) was dispersed in a solvent composed of ethyl cellulose and butyl carbitol to obtain a paste.

  After forming an aluminum thin film on the upper surface of the glass substrate, the aluminum thin film is patterned by a photolithography method to form a wiring pattern. An insulating layer mainly composed of low melting point glass is formed on the upper surface of the wiring pattern, and a through-hole portion communicating with the wiring conductor is further provided in the insulating layer. Then, an anode conductor mainly composed of graphite was formed on the upper surface of the insulating layer so as to close the through hole, and was fired to complete the anode substrate.

Thereafter, a phosphor layer containing the phosphor (1) (a phosphor emitting red light represented by Ca _0.992 SiAlN ₈ : Eu ^0.008 ) is printed on the upper surface of the anode conductor by a screen printing method to form a phosphor layer. After that, the glass substrate including the phosphor layer is baked at about 500 ° C. to complete the anode substrate.

  A box-shaped container is assembled by combining the anode substrate and a box-shaped container portion facing the anode substrate so that a grid electrode or the like is disposed therein, and is heated in a 400 to 500 ° C. atmosphere to have a low melting point as an adhesive Glass is melted to seal and form an airtight container. Next, in an atmosphere of 300 to 400 ° C., an internal gas was sucked and sealed from an exhaust hole provided in the hermetic container, and a fluorescent display tube was produced in which the inside was evacuated.

Only when an anode voltage of 30 V or higher was applied to the anode of the fluorescent display tube, light emission of the phosphor layer could be confirmed. However, when an impact test was performed on the fluorescent display tube, the phosphor layer was detached from the anode substrate.
As described above, the oxynitride phosphor according to the present invention has excellent performance as a phosphor for a fluorescent display tube as shown in the above items (1) and (2). The inventor of the present application has found for the first time that there is a problem in terms of mechanical strength in terms of mounting when used alone as a phosphor for a fluorescent display tube because of poor adhesion to a glass substrate.

2. Embodiment of a fluorescent display tube provided with a phosphor obtained by mixing conductive fine particles with the oxynitride phosphor (corresponding to the invention according to claim 13)
As described above, the oxynitride phosphor according to the present invention alone has poor adhesion to a glass substrate, and there is a problem in using it alone as a phosphor for a fluorescent display tube. I devised a structure to overcome.

  In the fluorescent display tube according to the present invention, an electron beam excited phosphor is formed on the upper surface of the anode formed on the upper surface of the insulating glass substrate by a thick film printing method or the like, and the substrate on which the phosphor layer is formed is a part. An electron source is disposed in an airtight container, and the phosphor layer is excited by a 100 eV or less electron beam emitted from the electron source to emit light.

Therefore, the phosphor layer must not be detached or dropped by an external impact or the like. Furthermore, in order for the phosphor layer excited by an electron beam of 100 eV or less to emit light, the resistance of the phosphor layer is set to 500 Ω / cm ² or less in order to suppress the voltage drop in the phosphor layer to 1.0 V or less. It must be done.

Therefore, as a result of intensive studies based on trial and error experiments, the inventor of the present application has conventionally used In ₂ O used for the purpose of reducing the resistivity of ZnCdS: Ag-based phosphors and other highly insulating phosphors. _{3 Based on} the technical assumption that at least one metal oxide selected from ZnO and SnO ₂ can function not only as a conductive agent but also as an adhesion enhancing material, Mixed in the phosphor layer. As a result, the resistance of the phosphor layer is 500 Ω / cm ² or less, the voltage drop in the phosphor layer is suppressed to 1.0 V or less, and the adhesion to the glass substrate is improved. As a layer, we were able to achieve a remarkable effect.

  That is, since the average particle diameter of the phosphor powder used in the present invention is 2 μm to 3 μm, the average particle diameter of the metal oxide as the conductive agent and adhesion enhancing material is larger than the average particle diameter of the phosphor powder. It was made into 0.5 micrometer or less small. As a result, as the resistivity decreases, the phosphor particles of the present invention can be in close contact with each other with a metal oxide having a smaller diameter interposed between the particles, and can be in close contact with the surface of a flat glass substrate. As a result, it was possible to achieve an improvement in mechanical performance that the phosphor layer was less likely to be detached and dropped from the glass substrate due to external impact or the like, and the phosphor was less likely to chip.

  When the average particle diameter of the metal oxide is 0.2 μm or less, the metal oxide is more resistant to external impacts and the like than when a metal oxide having an average particle diameter of 0.5 μm or less is mixed, and the phosphor layer is removed. It was confirmed that separation / falling hardly occurred.

The effect of enhancing the adhesion of the phosphor layer to the glass substrate and the anode in this example will be described in detail.
After carrying out the following evaluation test for evaluating the adhesion state of the phosphor layer to the anode and the like, the phosphor layer has no peeling / detachment, and the phosphor layer is expected when an electric signal is supplied to the anode. It is necessary to emit light in the mode of.

The evaluation test is performed according to the following procedures 1) to 3).
1) First, the fluorescent display tube is fixed to the test apparatus, and is then vibrated for 2 hours in each of the x, y, and z directions with a total amplitude of 1.5 mm, a frequency of 10 to 55 Hz, and a sweep time of 10 minutes.
2) Excitation is performed in the x, y, and z directions for 2 hours at an acceleration of 4G, a frequency of 55 to 200 Hz, and a sweep time of 10 minutes.
3) A maximum acceleration of 100 G, a working time of 6 ms, and half-wave sine waves x, x ′, y, y ′, z, and z ′ are given three impacts in total for 18 times.

  The phosphor layer formed by mixing phosphor, which is newly used in the fluorescent display tube of this example, and containing Ca, Si, N, and Eu as the emission center, and conductive fine particles made of a metal oxide is the evaluation described above. As a result of the test, no peeling or detachment occurred, and light emission with sufficient luminance with the intended color could be obtained by a normal low-speed electron beam with 30 V, which is a normal anode voltage of a fluorescent display tube.

Hereinafter, more specific examples in the present embodiment will be described as examples.
Example 1
An example of a fluorescent display tube using a phosphor emitting orange light expressed by Ca ₂ Si ₅ N ₈ : Eu ^0.008 , a conductive agent, and In ₂ O ₃ as a detachment / falling prevention agent.
In ₂ O ₃ having an average particle size of 0.5 μm was mixed as a conductive agent / adhesive strength enhancer (hereinafter simply referred to as a conductive agent) into an orange light emitting phosphor represented by Ca ₂ Si ₅ N ₈ : Eu ^0.008 . . This was dispersed in a solvent composed of ethyl cellulose and butyl carbitol to obtain a paste.

  After forming an aluminum thin film on the upper surface of the glass substrate, the aluminum thin film is patterned by a photolithography method to form a wiring pattern (not shown). An insulating layer mainly composed of low melting point glass is formed on the upper surface of the wiring pattern, and a through-hole portion communicating with the wiring conductor is further provided in the insulating layer. Then, an anode conductor containing graphite as a main component is formed on the upper surface of the insulating layer so as to close the through hole and fired.

Thereafter, a paste containing phosphor emitting orange light represented by Ca ₂ Si ₅ N ₈ : Eu ^0.008 is printed on the upper surface of the anode conductor by a screen printing method to form a phosphor layer, and then fired at about 500 ° C. Thus, the anode substrate is completed.

  A box-shaped container is assembled by combining the anode substrate and a box-shaped container portion facing the anode substrate so that a grid electrode or the like is disposed therein, and is heated in a 400 to 500 ° C. atmosphere to have a low melting point as an adhesive Glass is melted to seal and form an airtight container. Next, in an atmosphere of 300 to 400 ° C., an internal gas was sucked and sealed from an exhaust hole provided in the hermetic container, and a fluorescent display tube was produced in which the inside was evacuated.

  As a result of applying 20 V to the anode electrode of the fluorescent display tube and measuring the emission color and luminance of the phosphor layer, yellow-orange emission was obtained.

As shown in FIG. 2, in this example, a plurality of types of fluorescent display in which In ₂ O ₃ having an average particle size of 0.5 μm or less is added to the phosphor in a plurality of mixed amounts within a range of 1 wt% to 40 wt%. A tube was made.

  When the addition amount was 0.5 wt%, the relative luminance was only 5%, and the phosphor layer was sometimes peeled off. The relative luminance at 1.0 wt% was 50%, and the phosphor layer did not peel off. When the addition amount is 40 wt%, the relative luminance is 65%. However, when the addition amount is 50 wt%, the relative luminance is reduced to 40%, and the phosphor layer does not peel off, but there are problems such as a decrease in luminance. Therefore, the addition amount of the conductive fine particles is desirably 1 wt% to 40 wt%.

Even when In ₂ O ₃ having an average particle diameter of 0.5 μm or less, which is the conductive agent, is changed to 0.5 μm or less ZnO or SnO ₂ , the same effect can be obtained, and In ₂ O _{3 having} an average particle diameter of 0.2 μm or less. Similar effects were obtained even when ZnO and SnO ₂ were used.
Further, the same was true for In, Zn and Sn metal fine particles having an average particle diameter of 0.5 μm or less.

  From the above, the nitride-based phosphor of this example alone has low adhesion strength to the glass substrate. However, if an appropriate amount of conductive fine particles having a predetermined particle diameter is mixed, the conductivity of the phosphor layer is improved and the glass is improved. It can be seen that the adhesion strength to a smooth and flat substrate surface such as a substrate is enhanced, and it is useful for a fluorescent display tube in which phosphor particles must be adhered to a flat and smooth glass surface.

(Example 2)
15 wt% of ZnO fine particles having an average particle diameter of 0.5 μm were mixed as a conductive agent with a phosphor emitting red light represented by Ca _0.992 SiAlN ₈ : Eu ^0.008 . This was dispersed in a solvent composed of ethyl cellulose and butyl carbitol to obtain a paste.

  Using the phosphor paste, a fluorescent display tube was prepared in the same manner as in Example 1. As a result of the evaluation test, no peeling or detachment occurred, and a low-speed electron beam at a normal anode voltage of the fluorescent display tube was used. Red light emission was obtained with practical brightness.

(Example 3)
Ca _1.4 Si _8.08625 Al _31.375 O _0.1125 N _15.8875 : 15 wt% of SnO ₂ fine particles having an average particle diameter of 0.5 μm as a conductive agent were mixed with a phosphor exhibiting yellow light emission represented by Eu ^0.075 . This was dispersed in a solvent composed of ethyl cellulose and butyl carbitol to obtain a paste.
Using the phosphor paste, a fluorescent display tube was prepared in the same manner as in Example 1. As a result of the evaluation test, no peeling or detachment occurred, and a low-speed electron beam at a normal anode voltage of the fluorescent display tube was used. The desired yellowish white light emission was obtained with practical brightness.

3. A second phosphor layer in which conductive fine particles are mixed with the oxynitride phosphor, and another first phosphor layer are provided on the second phosphor layer to emit light from the first phosphor layer. Embodiment of a color conversion type fluorescent display tube which is irradiated after being converted in color by two phosphor layers (corresponding to the inventions according to claims 1 to 3 and claims 6 to 12)
In the fluorescent display tube of this example, the phosphor layer is excited by a first phosphor (for example, ZnO: Zn) having an emission peak wavelength in the range of 400 nm to 550 nm and visible light of 450 nm to 550 nm, and has a wavelength of 560 nm to 680 nm. A second phosphor that emits light having a light emission peak in the range (the oxynitride phosphor), and a conductive fine particle that attaches the second phosphor layer to the glass substrate and the anode and imparts conductivity. (For example, the In ₂ O ₃ or the like).

  (1) A type in which the first phosphor and the second phosphor are respectively layered and laminated with each other, and light emitted from the first phosphor is color-converted by the second phosphor and irradiated (Example) 4 to 8)

Example 4
As a conductive agent, In ₂ O ₃ having an average particle size of 0.5 μm was mixed with the mixed phosphor in an amount of 10 wt% as an orange light emitting phosphor represented by Ca ₂ Si ₅ N ₈ : Eu ^0.008 . This was dispersed in a solvent composed of ethyl cellulose and butyl carbitol to obtain a paste.

  As shown in FIG. 3, an anode conductor 11 made of a light-transmitting striped aluminum thin film is formed on the upper surface of a glass substrate 10 which is a light-transmitting insulating substrate constituting a part of an airtight container of a fluorescent display tube, and the same. A wiring pattern 12 connected to is formed. A phosphor layer using the low-speed electron beam phosphor of the present invention is formed on the upper surface of the anode conductor 11 so as to cover the opening of the anode conductor 11 with a film thickness of 10 μm by screen printing, and then dried at 100 ° C. A second phosphor layer 20 was formed.

  Thereafter, a paste in which a ZnO: Zn phosphor is dispersed in a solvent composed of ethyl cellulose and butyl carbitol is laminated and printed on the upper surface of the second phosphor layer 20, and then fired at about 500 ° C. to form the first phosphor. Layer 30 is formed to complete the anode substrate for a fluorescent display tube.

  The glass substrate 10 and the opening side of the box-shaped container part are combined to form a box-shaped container so as to incorporate electrodes / structures such as grid electrodes, etc., and heated in an atmosphere of 400 to 500 ° C. as an adhesive The low melting point glass is melted to seal the joining portion, thereby forming an airtight container.

  Next, after suctioning the internal gas from a suction hole provided in a part of the container in an atmosphere of 300 to 400 ° C. to bring the inside into a high vacuum state, the suction hole is sealed, and the inside is in a vacuum-tight state. A fluorescent display tube was prepared.

  When 20 V, 30 V, and 50 V were applied to the anode electrode of the fluorescent display tube and the light emission luminance and the light emission color were observed, as shown in Table 1 (“the present invention” in the table), it was practically sufficient as a fluorescent display tube. A pure yellow-orange luminescence was obtained with the desired brightness.

  That is, as shown in FIG. 3, the green light emission of ZnO: Zn, which is the first phosphor, is converted into the yellow-orange light emission by the second phosphor layer 20 including the second phosphor. Observed through the substrate 10.

In contrast, a fluorescent display tube manufactured under the same conditions as in Example 4 except that In ₂ O ₃ is not used is shown as a comparative example, and the performance is also shown in Table 1 (“Comparative Example” in the table). 1 ").

  As is clear from the comparison between the two in Table 1, in the comparative example, light emission was obtained only when an anode voltage of 30 V or higher was applied, and the luminance was overwhelmingly smaller than in this example, which was not practical. . Further, as described above, in the comparative example, since the adhesion strength to the glass substrate is small, it is easily peeled off by mechanical vibration or the like and cannot be used.

(Example 5)
A phosphor emitting red light represented by Ca _0.992 SiAlN ₈ : Eu ^0.008 and ZnO fine particles as a conductive agent of 12% by weight with respect to the phosphor were dispersed in a solvent composed of ethyl cellulose and butyl carbitol to obtain a paste.

Using the phosphor paste, a fluorescent display tube was produced in the same manner as in Example 4. When a voltage of 20 V was applied to the anode electrode of the fluorescent display tube and the emission color and emission luminance were observed, the green emission of ZnO: Zn was converted as shown in Table 2 ("Invention of this application" in the table). Furthermore, practically sufficient purity of orange luminescence was obtained at a luminance of 500 cd / m ² .

On the other hand, a fluorescent display tube manufactured under the same conditions as in (Example 5) except that a red light emitting phosphor represented by Ca _0.992 SiAlN ₈ : Eu ^0.008 was used instead of the red light emitting phosphor was used as a comparative example. The performance was also shown in Table 2 (“Comparative Example 2” in the table).

  As is clear from the comparison between the two in Table 2, the light emission luminance at any anode voltage in the comparative example is only about 45% to 67% of the present invention, and in the present invention, it is constant in orange regardless of the anode voltage. On the other hand, in Comparative Example 2, the emission color also changes due to the anode voltage, and it cannot be used as a phosphor of a fluorescent display tube.

(Example 6)
Ca _1.4 Si _8.08625 Al _31.375 O _0.1125 N _15.8875 : A phosphor emitting yellow light represented by Eu ^0.075 and 30 wt% of ZnO fine particles as a conductive agent are mixed and dispersed in a solvent composed of ethyl cellulose and butyl carbitol to obtain a paste. .

  When a fluorescent display tube was prepared using the phosphor paste in the same manner as in Example 4, yellowish white light emission having a practically sufficient purity and luminance was observed.

(Example 7)
A phosphor emitting red light represented by Ca _0.992 SiAlN ₃ : Eu ^0.008 and 12 wt% of ZnO fine particles as a conductive agent were mixed and dispersed in a solvent composed of ethyl cellulose and butyl carbitol to obtain a paste.

  A fluorescent display tube was prepared in the same manner as in Example 5 except that the thickness of the phosphor layer using the phosphor paste was changed to 5 μm. As a result, red light emission from the sialon phosphor and green light emission from the ZnO: Zn phosphor were obtained. As a result, white light emission having a practically sufficient purity and brightness was obtained.

(Example 8)
A second phosphor that emits red light represented by Ca _0.992 SiAlN ₃ : Eu ^0.008 and ZnO fine particles as a conductive agent were mixed at 12 wt%, and dispersed in a solvent composed of ethyl cellulose and butyl carbitol to obtain a paste.

A second phosphor layer was formed on the surface of the glass substrate using this paste. Next, In ₂ O ₃ as a conductive agent is mixed with ZnS: Zn blue light-emitting phosphor as the first phosphor as an upper layer at a ratio of 7 wt% with respect to the ZnS: Zn blue light-emitting phosphor, and ethyl cellulose and A paste was formed by dispersing in a solvent composed of butyl carbitol, and this was formed into a layer on the second phosphor layer in the same manner as in Example 4 to produce a fluorescent display tube in the same process. Pale red light emission with a purity and luminance sufficient for practical use was observed.

4). Fluorescent display having a phosphor layer including a ZnO-based first phosphor, Ca, Si, N, and the second oxynitride-based phosphor containing Eu as an emission center, and conductive fine particles Embodiment of the pipe (corresponding to the invention according to claims 1 and 4 to 12)
In the fluorescent display tube of this example, the phosphor layer is excited by a first phosphor (for example, ZnO: Zn) having an emission peak wavelength in the range of 400 nm to 550 nm and visible light of 450 nm to 550 nm, and has a wavelength of 560 nm to 680 nm. A mixture of a second phosphor that emits light having an emission peak in the range (the oxynitride phosphor) and conductive fine particles (for example, the In ₂ O ₃ ) was formed as a single phosphor layer. Therefore, as described in the following examples, various emission colors can be obtained by mixing ratios of the two types of phosphors.

Example 9
The phosphor emitting orange light represented by Ca ₂ Si ₅ N ₈ : Eu ^0.008 , the ZnO: Zn phosphor, and the two phosphors are mixed at different weight ratio mixing ratios, and the average particle size is 0 as a conductive agent. 0.5 μm of In ₂ O ₃ was mixed with the mixed phosphor at 10 wt%. This was dispersed in a solvent composed of ethyl cellulose and butyl carbitol to obtain a paste.

  A fluorescent display tube was produced in the same manner as in Example 1 using the phosphor paste. Table 3 shows the results of observing the color tone and luminance of the mixed phosphor by changing the ZnO: Zn phosphor ratio from 0.2 wt% to 100 wt%. As a result, in the range of 1 wt% to 70 wt%, different light emission ranging from orange to light yellowish green with practical luminance was obtained.

(Example 10)
A phosphor emitting red light represented by Ca _0.992 SiAlN ₈ : Eu ^0.008 and a ZnO: Zn phosphor are mixed at different weight mixing ratios, and 12 wt% of ZnO fine particles are mixed as a conductive agent to obtain ethyl cellulose and butyl carbitol. Dispersed in a solvent consisting of

  A fluorescent display tube was prepared in the same manner as in Example 1 using the phosphor paste. Table 4 shows the results of observing the color tone and luminance of the mixed phosphor by changing the ZnO: Zn phosphor ratio from 0.2 wt% to 100 wt%. As a result, in the range of 1 wt% to 70 wt%, light emission having a practical tone with different colors from red to white was obtained.

As a comparative example, instead of a phosphor emitting red light represented by Ca _0.992 SiAlN ₈ : Eu _0.008 , a Bengala red pigment and a ZnO: Zn phosphor are used, and ZnO fine particles are mixed as a conductive agent to obtain a phosphor paste. When the fluorescent display tube was manufactured and manufactured in the same manner as in Example 1, the chromaticity changed only slightly from the emission color of the red beggar red pigment.

(Example 11)
Ca _1.4 Si _8.08625 Al _31.375 O _0.1125 N _15.8875 : A phosphor emitting yellow light represented by Eu _0.075 is mixed with ZnO: Zn phosphor at different weight mixing ratios, and 30 wt% of ZnO fine particles are mixed as a conductive agent. The paste was dispersed in a solvent composed of ethyl cellulose and butyl carbitol.

  A fluorescent display tube was produced in the same manner as in Example 1 using the phosphor paste. As a result, yellowish white light emission was obtained.

5. Other Examples In the examples described above, the second phosphor may contain an alkaline earth element (Mg, Sr or Ba) other than Ca, Si and N, and Eu as the emission center. If Sr ₂ Si ₅ N ₈ or Ba ₂ Si ₅ N ₈ is used, the luminance of the phosphor is higher than that of Ca ₂ Si ₅ N ₈ .
In the embodiments described above, In ₂ O ₃ , ZnO, and SnO ₂ are exemplified as the conductive fine particles, but at least one kind of metal fine particles selected from In, Zn, and Sn is used. Experimental results were obtained. In addition, substantially the same result can be obtained even when the above metal oxide and / or metal is appropriately selected and mixed.

In Examples 9, 10 and 11, the ZnO: Zn phosphor is exemplified as the first phosphor to be mixed with the sialon phosphor which is the second phosphor in the present invention. However, as the first phosphor, Even if other Zn-based phosphors other than the above, for example, ZnS: Zn, ZnS: Ag, ZnGa ₂ O ₄ or the like are used, the effect corresponding to the emission color of each phosphor can be obtained.

Moreover, in the said Example 4-8, ZnO: Zn fluorescent substance and ZnS: Zn are illustrated as fluorescent substance of the 1st fluorescent substance layer superimposed on the layer of the sialon fluorescent substance which is the 2nd fluorescent substance in this invention. However, even if another Zn-based phosphor other than the above, for example, ZnS: Ag or ZnGa ₂ O ₄ is used as the first phosphor, an effect corresponding to the emission color of each phosphor can be obtained.

  As described above, according to the present invention, Cd-free, resistant to gas in the fluorescent display tube, has a good lifetime characteristic, and is highly efficient in the blue-green emission of ZnO: Zn with high reliability. The oxynitride phosphor optimized for color conversion can be used to achieve white light emission and yellow to red warm color light emission with high brightness and little color change over time. When unevenness of brightness is not easily generated and conductive fine particles are mixed, the fluorescent display tube has good adhesion to the insulating substrate constituting the vacuum-tight container and is difficult to peel off. Further, the fluorescent display tube emits white, yellow to red light. As a result, preferable performance can be realized.

Excitation wavelength distribution and emission wavelength distribution of oxynitride-based phosphor (phosphor (1), (2), (3)) containing Ca, Si, N and Eu as a light emission center according to an embodiment of the present invention FIG. 5 is a diagram showing graphs showing emission wavelength distributions of ZnO: Zn phosphors used in the examples. In the embodiment of the present invention, it is a diagram showing a graph showing the light emission luminance of the fluorescent display tube of adding by changing the mixing amount of In ₂ O ₃ with respect to the phosphor. It is sectional drawing of the anode substrate (glass substrate) of the fluorescent display tube which concerns on an example of embodiment of this invention.

Explanation of symbols

10 ... glass substrate 11 ... anode conductor 12 ... wiring pattern 20 ... second phosphor layer as the light-transmitting insulating substrate constituting a part of the airtight container of the fluorescent display tube _{(Ca 2 Si 5 N 8:} Eu 0.008)
30: First phosphor layer (ZnO: Zn)

Claims (14)

A vacuum hermetic container; an electron source disposed in the vacuum hermetic container; an anode disposed on an inner surface of an insulating substrate constituting the vacuum hermetic container; and the electron source formed on the anode. In a fluorescent display tube having a phosphor layer that emits light due to a collision of electrons emitted from
The phosphor layer has a first phosphor having an emission peak wavelength in the range of 400 nm to 550 nm, and a second fluorescence emitting light having an emission peak in the range of 560 nm to 680 nm when excited by visible light of 450 nm to 550 nm. A fluorescent display tube comprising: a body; and conductive fine particles that attach the phosphor layer to the anode and impart conductivity to the phosphor layer. The phosphor layer includes a second phosphor layer in which the second phosphor is laminated on the anode, and a first phosphor on the second phosphor layer. A first phosphor layer comprising:
Upon receiving the electron impact, the first phosphor layer emits light, and the second phosphor layer is excited by the light to emit light, and light from the second phosphor layer is translucent. 2. The fluorescent display tube according to claim 1, wherein the fluorescent display tube is irradiated outside the vacuum hermetic container through the insulating substrate and the translucent anode. 3. The fluorescent display tube according to claim 2, wherein the conductive fine particles are dispersed in the second phosphor layer. The fluorescent display tube according to claim 1, wherein the phosphor layer is a mixture of the first phosphor, the second phosphor, and the conductive fine particles. The fluorescent display tube according to claim 4, wherein a mixing weight ratio of the first phosphor and the second phosphor is 0.01 to 0.7 to 1. 6. The fluorescent display according to claim 1, wherein the second phosphor includes at least an alkaline earth element (Mg, Ca, Sr, or Ba), Si, N, and Eu as an emission center. tube. The fluorescent display tube according to claim 6, wherein the alkaline earth element is Ca. 6. The fluorescent display tube according to claim 1, wherein the second phosphor is Ca ₂ Si ₅ N ₈ activated with Eu. The fluorescent display tube according to claim 1, wherein the second phosphor is Ca-α-sialon in which Eu is inactivated. 6. The fluorescent display tube according to claim 1, wherein the second phosphor is CaSiAlN ₃ in which Eu is inactivated. The first phosphor is at least one phosphor selected from the group consisting of ZnO: Zn, ZnS: Zn, ZnS: Ag, or ZnGa ₂ O _4. Item 11. The fluorescent display tube according to Item 10. The conductive fine particles are at least one metal oxide and / or metal selected from In ₂ O ₃ , ZnO, SnO ₂ , In, Zn, and Sn. The fluorescent display tube as described. The fluorescent display tube according to claim 1, wherein an amount of the conductive fine particles is 1 wt% to 40 wt% with respect to the phosphor. A vacuum hermetic container; an electron source disposed in the vacuum hermetic container; an anode disposed on an inner surface of an insulating substrate constituting the vacuum hermetic container; and the electron source formed on the anode. In a fluorescent display tube having a phosphor layer that emits light due to a collision of electrons emitted from
The phosphor layer includes Ca, Si, N, and Eu as an emission center, and is formed on the upper surface of the anode and is excited by electrons emitted from the electron source to emit yellow to red light, and A fluorescent display tube, comprising: conductive fine particles that are mixed with a phosphor to bring the phosphor layer into close contact with the anode and impart conductivity to the phosphor layer.

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