JPS5931551B2 - phosphor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a phosphor for excitation with a slow electron beam that emits light when excited by electrons accelerated at a low voltage of, for example, several volts to several + volts.

In recent years, fluorescent display devices have been increasingly used as display devices for various electronic and electrical devices, as they can be driven at low voltages, consume little power, and provide bright, easy-to-read displays. I'm getting used to it.

This fluorescent display device causes electrons emitted from a filament-shaped cathode that is heated by electricity to strike an anode that has a phosphor layer on its top surface and is selectively applied with a positive anode voltage. , the phosphor layer is excited to emit light to obtain a display of characters, figures, etc.

In this case, the phosphor layer deposited on the anode is constituted by a phosphor that can provide sufficient luminance for display with a low accelerating voltage, a so-called slow electron beam excited phosphor.

By the way, as a phosphor for slow electron beam excitation used in this fluorescent display device, conventionally ZnO:
A Zn-based phosphor was used.

This ZnO:Zn-based phosphor has a luminescence threshold voltage,
The so-called dead voltage is extremely low at around 2V,
Further, in general, sufficient luminance for display can be obtained with an anode voltage of about 10 V to 20 V, making it an extremely excellent phosphor for low-speed electron beam excitation. However, the ZnO:Zn-based phosphor emits light in a green color when excited by an electron beam, and therefore, in conventional fluorescent display devices, the light emission color is limited to a green color.

On the other hand, as the application fields of fluorescent display devices expand,
There are increasing demands from various quarters for diversification of display luminescent colors.

For example, when displaying a warning, a red display is preferable to a green display. Furthermore, if one display device is divided into multiple display areas and the emitted light color in each display area is changed, it is possible to display multiple display targets and the amount of input exceeding a set value. This has the advantage of being easier to view, and furthermore, the amount of displayed information can be expected to increase significantly.

In order to meet the above-mentioned demands, various efforts have been made in various fields to develop phosphors that emit light in colors other than green when excited by slow electron beams.

For example, ZnS:Ag series, ZnS:
Various conductive materials are mixed with Cu-based phosphors, (Zn, Cd)S:Afl-based phosphors, or rare earth phosphors such as Y202S:Eu to improve the conductive envelope and reduce speed. Efforts have been made to create a phosphor for electron beam excitation, and proposals have been made to create a new phosphor by adding rare earth elements such as Eu to SnO2, which is originally a conductive material. However, the phosphors that have been obtained to date are
Excitation with a slow electron beam has not yet reached the point where sufficient brightness for display can be obtained, and the emission threshold voltage is as high as about a dozen volts, and the normal operating voltage is several + volts or more.
It was still insufficient as a phosphor for low-speed electron beam excitation. For example, the aforementioned phosphor for high-speed electron beam excitation is generally an insulating material, but if a large amount of a conductive material is mixed in, the conductive envelope of the phosphor is improved and the emission threshold voltage and operating voltage are reduced. can be seen.

However, the conductive material is only used to improve the conductivity of the luminescent material;
It does not contribute in any way to light emission.

Therefore, when mixing the above-mentioned conductive materials to obtain a phosphor for slow electron beam excitation, if the mixing ratio is increased, the amount of the phosphor decreases by that amount, and the light emitting portion decreases. As a result, the luminance of the emitted light decreases, resulting in a drawback that sufficient luminance for display cannot be obtained.

Furthermore, since it contains a conductive material that does not emit light,
Nonuniform mixing tends to cause unevenness in light emission, which also poses problems in terms of display quality. By the way, when a rare earth element becomes a substituted atom in the parent body of a phosphor, the energy added to the phosphor is transferred to the substituted atom by resonance transfer, and the intraatomic transition causes the element to emit light unique to the element. It is known.

Therefore, materials that inherently have conductivity, such as Sn
If O2 is used as a matrix for a phosphor, excitation with a slow electron beam becomes possible, and as mentioned above, a SnO2:Eu phosphor in which a rare earth element such as -Eu is added to SnO2 as an activator has been proposed. ing. However, this S
In the nO2:Eu phosphor, the parent Sn is a tetravalent element, whereas the activator Eu is trivalent, so the amount of Eu that can be added as an activator is extremely small. Due to this low activator concentration, saturation customization occurs at low brightness, and there is a problem that sufficient display brightness cannot be obtained.

On the other hand, as a result of studying the problems in the various phosphors for excitation with slow electron beams mentioned above, the present inventors have developed a trivalent material that can be doped with rare earth elements at a high concentration and as a stable phosphor matrix material. Select In2O3 consisting of In, and
After conducting various studies by adding rare earth elements such as Eu to 2O3, we have proposed a new phosphor that emits light in various colors including red with a slow electron beam of several volts to several + volts.

A phosphor made of In2O3 as a matrix and to which a rare earth element is added as an activator has a conductive layer itself, so for example, Y2O3:EU or Y2O2S:E
There is no need to add conductive materials such as U to reduce resistance, and since rare earth elements can be added at high concentrations, uneven brightness and saturation phenomena at low brightness can be prevented.
It has excellent features as a phosphor for low-speed electron beams.

However, as a result of continuing various researches to further improve the luminous efficiency of the above-mentioned In2O3-based phosphor, the inventor discovered that In2O3 was not used as the matrix alone, but In2O3 was used as the matrix.
By using a mixed crystal (In, -XYx) 203 in which Y2O3 is added to the extent that 2O3 does not damage the conductive group, the energy stored in the matrix is transferred to the luminescent center formed by the rare earth element added as an activator. It was discovered that the information can be transmitted efficiently, leading to the present invention. That is, the present invention uses a mixed crystal represented by the general formula (n1-XYX)203 as a matrix, adds Eu to this matrix as an activator, and is excited by a slow electron beam to easily emit light in a red or other color. The object of the present invention is to provide a phosphor for low-speed electron beam excitation.

Hereinafter, the present invention will be described with reference to specific examples.

First, as a starting material for the phosphor of the present invention, In2O3,
Y2O3 is prepared, and Eu, which becomes an activator, is EU2
Obtained in the form of O3. Then, predetermined amounts of In2O3 and Y2O3 are weighed.

In this case, it is necessary to keep the mixing ratio of Y2O3 to In2O3, that is, the mixed crystal ratio
is appropriately selected from the range O<x≦0,6.

In addition, the amount of Eu to be added is selected within the range of 10-3 atoms/mol to 10-1 atoms/mol per mol of the parent material, so as to form sufficient luminescent centers in the parent material and not cause concentration quenching. It is better.

For example, if the mixed crystal ratio x is selected to be 0.1, that is, In2
O3O. Weigh out 0.1 mol of Y2O3 for 9 mol,
Furthermore, in order to add 10@-2 atoms/mol of Eu, 0.005 mol of EU2O3 is weighed per 1 mol of the base material.

After these starting materials were put into a nitric acid solution and dissolved by heating, they were further heated and boiled down to a syrup-like consistency, and a predetermined amount of distilled water was added to this to form an aqueous solution of nitrates. make.

Thereafter, a saturated solution of oxalic acid is added to the aqueous solution to produce an oxalate salt by coprecipitation, which is filtered, washed with water, dried, and then filled into an alumina boat and fired.

The firing is preferably carried out in air, preferably in an oxygen atmosphere, at a temperature of about 800°C to 1500°C, for about 1 to 12 hours. In this case, in order to improve the luminance, the firing is divided into two stages; for example, after firing at 1000°C for 1 hour, the firing temperature is increased to 1300°C and firing is performed for another 2 to 10 hours. It is also possible to take the following operation means. Furthermore, during this firing, in order to promote the growth of the particle size of the phosphor particles, B2O3, Ll2O, SlO2, Ll2SiO3,
Ll2GeO3, Na2cO3, etc. may be added alone or in an appropriate combination.

Thus, through the above-described process, a (InO.9YO.l)203:Eu phosphor exhibiting a white to pale yellow color in a powder state is obtained.

Next, in order to investigate the special characteristics of the phosphor obtained as described above, the present inventors manufactured a phosphor display tube having the structure shown in FIGS. 1A and 1B.

FIG. 1a is a partially cutaway plan view of the main part of a fluorescent display tube manufactured by the present inventor, and FIG. 1b (well, an enlarged sectional view of the main part).

Here, 1 is a substrate made of an insulating material such as glass or ceramics, and a wiring conductor 2 is first deposited on this substrate 1, and then this wiring conductor 2 is attached to an insulator with a through hole 3a formed at a predetermined position. Cover with layer 3.

This insulating layer 3 is made of, for example, low-melting-point fritted glass as a main component, mixed with a binder, an organic solvent, and, for example, a black pigment to form a paste, which is then printed and fired. 4 is an anode conductor formed, for example, in the shape of a Japanese character on the insulating layer 3, and (InlXYX) 20 according to the present invention obtained through the process described above is placed on this anode conductor.
3: A phosphor layer 5 made of EU phosphor is deposited by any suitable means such as well-known screen printing, electrodeposition or precipitation to form an anode 6.

Further, the anodes 6 are arranged in a Japanese character shape to form a single digit pattern display section 7. Further, 8 is a mesh-shaped control electrode disposed above facing the pattern display section 7, 9 is a filament-shaped cathode that is heated with electricity and emits electrons, and 10 is formed into, for example, a flat-bottomed boat shape. , a front envelope 11, which is sealed to the periphery of the substrate 1 to form a vacuum envelope together with the substrate 1 and maintains each electrode in a high vacuum atmosphere, has at least a transparent display window; This is an introduction terminal that airtightly penetrates the sealed portion between the substrate 1 and the front enclosure 10, and is used to introduce a drive signal to each of the electrodes. That is, in the fluorescent display tubes shown in FIGS. 1A and 1B, the phosphor layer 5 of the conventionally known numeric display fluorescent display tube is replaced with the (n1-XYX)203:Eu phosphor according to the present invention. It was formed by

Thus, a heating voltage is applied to the cathode 9 of the fluorescent display tube shown in FIGS. 1A and 1B, a control voltage is applied to the control electrode 8, and an anode voltage is applied to the anode 6, so that the fluorescent display tube operates as a fluorescent display tube. In this case, as shown in FIG. 2, the anode 6 starts to emit red light when the anode voltage exceeds 6 to 8 V, and by further increasing the anode voltage to 20 to 50 V, the anode 6 starts emitting light in red. The brightness of the red light emitted from the display increases, and sufficient brightness for display can be obtained without causing uneven light emission.

In this case, the emission spectrum has a relatively linear spectrum with a peak value near 612 to 613 nm as shown in FIG. 3, and a good red display can be obtained.

That is, (In,XY2)0 which is an embodiment of the present invention
3: Since the Eu phosphor contains 1n203 in the matrix itself, it has a conductive envelope, which prevents charging of the phosphor surface by low-speed electrons that strike the phosphor, and the phosphor is Becomes more efficiently excited.

In addition, since the matrix is composed of a mixed crystal of In2O3 and Y2O3, the energy added to the matrix is efficiently transmitted to the luminescent center, and from this point of view, the luminous efficiency is significantly improved. expected.

Furthermore, since Eu as an activator can be added to the matrix (n]-XYX)203 at a high concentration, saturation discharge does not occur at low brightness, and the anode voltage can be adjusted as shown in Figure 2. As the luminance rises, the luminance also increases, and since no non-luminescent substances are mixed, there is no reduction in the luminescent area in the phosphor layer 5 or uneven luminescence, and high-quality high-quality light can be obtained using a low-speed electron beam. display will be available.

By the way, in the above-mentioned embodiment, the base (In, -XY
X) An example is shown in which Eu is used as an activator added to 203, but this activator is limited to Eu (including Eu, Ce, Fr, Yb, Sm ，
At least one type of element selected from rare earth elements such as these can be applied, and by changing this activator, for example, if the activator is Ce or S, red light emission similar to that of Eu can be obtained. The color of the emitted light can also be changed as appropriate, for example, green light can be obtained by using Er as an activator. Furthermore, the phosphor according to the present invention can be used not only as a fluorescent display tube, but also as a phosphor that performs display when excited by, for example, low-speed electron beams or ultraviolet rays generated in plasma. . As described above, the phosphor according to the present invention is made of In2 which itself has a conductive layer.
The matrix is a mixed crystal composed of O3 and Y2O3, and a rare earth element is added as an activator to this matrix to form a phosphor (for low-speed electron beam excitation).

Therefore, the phosphor of the present invention has a low emission threshold voltage of several volts, and an operating voltage of several tens of volts to several tens of volts, and is used, for example, in display units such as fluorescent display devices and plasma display devices. It has extremely excellent features as a phosphor, and can produce many effects.

Furthermore, since the phosphor according to the present invention emits red light when excited by a slow electron beam, it is possible to display colors that cannot be obtained with conventional ZnO:Zn-based phosphors, and it can be used in display devices. , for example, is extremely effective in displaying warnings, and is also extremely effective in diversifying display information.

Furthermore, since no means such as mixing non-luminescent substances are used to improve the conductivity of the phosphor itself, there is no uneven light emission and excellent effects such as high-quality display can be obtained. This is something to look forward to.

[Brief explanation of the drawing]

FIGS. 1A and 1B are a partially cutaway plan view and an enlarged cross-sectional view of a main part of a fluorescent display tube constructed using a phosphor according to the present invention, and FIG. 2 is a phosphor according to the present invention. FIG. 3 is a diagram showing a custom-made emission spectrum in one embodiment of the present invention, and FIG. 3 is a diagram showing a special range of luminance of the same embodiment. 4... anode conductor, 5... phosphor layer,
6... Anode, 9... Cathode.

Claims (1)

[Claims] 1 General formula (In_1_-_xY_x)_2O_3:E
A phosphor expressed by u (0<x≦0.6).