JPS5931552B2 - fluorescent display tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a fluorescent display tube using a phosphor that is excited to emit red light or the like by a so-called slow electron beam accelerated at a low mouth velocity voltage of several volts to several + volts. It is related to.

In recent years, fluorescent display tubes 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. It's getting old.

This fluorescent display tube allows electrons emitted from a filament-shaped cathode that is heated by electricity to strike an anode that has a phosphor layer coated on its top surface and that selectively applies 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 has a low
It is composed of a phosphor that can obtain luminance sufficient for display by applying a high-speed 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 tube, conventionally ZnOZ
An n-type 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 ZnOZn-based phosphor emits light in a green color when excited by an electron beam, and therefore, in conventional fluorescent display tubes, the light emitted in a conventional fluorescent display tube is limited to a green color.

On the other hand, as the field of application of fluorescent display tubes expands, there is a growing demand from various quarters for diversification of display emitted light colors.

For example, when displaying a warning, a red display is preferable to a green display. In addition, by dividing a single display tube into multiple display areas and changing the emitted light color in each display area, it is extremely easy to display multiple display targets and the amount of input exceeding a set value. Furthermore, there are advantages such as a significant increase in the amount of displayed information.

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

For example, ZnS, which is used as a phosphor in well-known color cathode ray tubes, emits light in various colors when excited by the impact of an electron beam accelerated by a high voltage of several hundred to tens of thousands of volts.
:A9 series, ZnS:Cu series phosphors, (Zn, Cd
) S:A9-based phosphors or rare earth phosphors such as Y2O2S:EU are mixed with various conductive substances to improve conductivity and are used as phosphors for low-speed electron beam excitation. However, since the conductive material itself is a non-luminescent material, the luminous area decreases and sufficient luminance cannot be obtained, and if the mixture is not uniform, the luminescence tends to be uneven, which is a problem in terms of display quality. There were also problems.

In addition, using SnO2, which has conductivity, as a matrix, E
In a fluorescent display tube using a SnO2:Eu phosphor that emits red light when exposed to a slow electron beam by adding u as an activator, Sn, which constitutes the matrix of the phosphor, is a tetravalent element. On the other hand, since the activator Eu is trivalent, the amount of Eu that can be added as an activator is extremely small, and due to this low activator concentration, it exhibits saturation characteristics at low brightness and There is a problem in that sufficient display brightness cannot be obtained as a phosphor for an optical display tube. On the other hand, the inventor
As a result of examining the problems with the various phosphors for low-speed electron beams mentioned above, we found that In
By selecting 2O3 and adding a rare earth element such as Eu as an activator to this base material, we are proposing a new phosphor that emits light in various colors including red.

This phosphor consists of N2O, which is made of trivalent In as a matrix.
Since trivalent Eu is added to this, the activator can be added at a high concentration, and since the matrix itself is conductive, there is no need to add a conductive substance, making it suitable for fluorescent display tubes. It has characteristics that are extremely suitable for use as a fluorescent material.

By the way, in a phosphor using a rare earth element as an activator, when the rare earth element becomes a substituted atom in the matrix of the phosphor, the energy applied to the matrix is transferred to the substituted atom by resonance transfer, and the atom It is known that the element exhibits luminescence due to internal transitions. Therefore, in order to improve the luminous efficiency of this type of phosphor, it is necessary to add rare earth elements at a high concentration within the range that does not cause concentration quenching within the host body, and to efficiently use the added energy to emit light. It is necessary to choose a material that transmits to the center.

The present invention was made in view of the above-mentioned circumstances, and
As a result of our study to improve the luminous efficiency of the In2O3:RE (RE is a rare earth element) phosphor proposed by the present inventor, we found that by using a mixed crystal of N2O3 and Y2O2S as a matrix, we added They discovered that energy was efficiently transmitted to the luminescent center, and by forming a phosphor layer using a phosphor based on this mixed crystal, they were able to obtain a phosphorescent display tube that emitted light in various colors, including red. It is something.

That is, in the present invention, trivalent In and Y, to which trivalent rare earth elements are easily added, are included as a matrix, and I
A phosphor display tube is constructed using a phosphor in which a matrix is formed of a mixed crystal of n2O3 and Y2O2S and Eu is added as an activator to the matrix. Hereinafter, one embodiment of the fluorescent display tube of the present invention will be described with reference to the drawings.

First, the phosphor used in the fluorescent display tube of the present invention will be described.

Using a mixed crystal of N2O3 and Y2O2S as a matrix, Eu
There are various methods to obtain phosphors doped with rare earth elements such as (n1-XYX) using EU2O3 containing In2O3, Y2O3, and activator Eu as starting materials (n1-XYX). 203: Form a Eu phosphor, mix it with a predetermined amount of S, and fire it to form (n1-X
YX) 202S: EU phosphor can be obtained.

Alternatively, by directly mixing a predetermined amount of N2O3, Y2O3, Eu2O3, and S, filling this mixture into a pot, etc., and firing it (Inl-XYx), 02S:E
u phosphor can be obtained.

In this case, it is necessary to keep the mixing ratio of Y2O3 to In2O3, that is, the mixed crystal ratio x, within a range that does not impair the conductivity of the matrix itself, and the mixed crystal ratio x
It is appropriate to select from the range of 0x≦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 1 mole of the parent material to form sufficient luminescent centers in the parent material and not cause concentration quenching. Good.

For example, if the mixed crystal ratio X is selected to be 0.1, that is, In2
O3O. Y2O3 and S were weighed so that Y2O3 was 0.1 mole per 9 moles, and Eu was further weighed at 10-2 atoms/
Add 0.005 mol of EU2O3 to 1 mol
Weigh the moles, mix and bake.

Further, the firing is preferably carried out in air, preferably in an oxygen atmosphere, at a temperature of about 800°C to 1,500°C,
This is done within about 12 hours.

In this case, in order to improve the luminance, the firing is divided into two stages, for example, after firing at 1,000°C for 1 hour,
Increase the firing temperature to 1,300℃ and continue for another 2 hours ~ 1
It is also possible to use an operation method of performing firing for about 0 hours. Furthermore, during this firing, B2O3 is added as a flux to promote the growth of the particle size as the phosphor particles.
Ll2O, SlO2, Li2SiO3, Li2GeO3
, Na2CO3, etc. may be added alone or in an appropriate combination.

Thus, through the above-described process, a 202S:Eu phosphor (InO.9YO.l) exhibiting a white to pale yellow color in a powder state is obtained.

Next, (n1-XYX)202s:E obtained as described above
An embodiment of the fluorescent display tube of the present invention using a u-fluorescent material will be described.

FIG. 1a is a partially cutaway plan view of the main part of a fluorescent display tube created by the inventor, and FIG. 1b is 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 placed in a predetermined position through holes 3.
It is covered with an insulating layer 3 formed with a.

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 on the insulating layer 3, for example in the shape of a Japanese letter, and on this anode conductor 4 is a phosphor layer 5 made of the above-mentioned (Inl-XYx)202S:Eu phosphor. The anode 6 is formed by applying the anode 6 by an appropriate method such as a conventional screen printing method, an electrodeposition method, or a precipitation method.

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, the phosphor display tube shown in FIGS. 1A and 1B has the phosphor layer 5 of a conventionally well-known numeric display tube.
(Inl-XYx)202S: Made of Eu phosphor.

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 characteristics are relatively linear with a peak value around 624 to 626 nm, as shown in FIG. 3, and a good red display can be obtained.

That is, the fluorescent display tube of the present invention has a phosphor layer 5.
The (Inl-XYx)202:Eu phosphor containing In2O3 in its matrix has electrical conductivity, and prevents charging of the surface of the phosphor by low-speed electrons that impinge on it. The phosphor is efficiently excited by the electron beam.

In addition, since the matrix is composed of a mixed crystal of In2O3 and Y2O2S, the energy applied to the matrix is
The light is now efficiently transmitted to the emission center, and from this point of view as well, a significant improvement in luminous efficiency is expected. Furthermore, E as an activator for the parent (Inl-XYX)202S
Since u can be added at a high concentration, it does not exhibit saturation characteristics at low brightness, and as shown in Figure 2, as the anode voltage increases, the luminance increases, and non-luminescent substances are mixed. Therefore, a high-quality display can be obtained as a phosphor display tube without a reduction in the light emitting area in the phosphor layer 5 or uneven light emission.

By the way, in the above-mentioned embodiment, the parent (Inl-XY
X) An example is shown in which Eu is used as an activator to be added to 202S, but this activator is not limited to Eu, and may include rare earth elements such as Ce, Er, Yb, and Sm. By changing this activator, for example, if the activator is Ce or Sm, red luminescence similar to Eu can be obtained, or if the activator is Ce or Sm, red luminescence similar to that of Eu can be obtained. When used as an activator, green light can be obtained, and the color of the light emitted by the fluorescent display tube can also be changed as appropriate. As described above, the fluorescent display tube according to the present invention is made of In2O, which itself has conductivity.
3 and Y2O2S as a matrix,
A phosphor layer is constructed using a phosphor in which a rare earth element is added as an activator to this matrix.

Therefore, in the fluorescent display tube of the present invention, the anode voltage at which display starts is several times low, and the operating voltage is also several tens to several tens.
Moreover, it is possible to obtain a display such as red, so conventional ZnO:
It is possible to display colors that cannot be obtained with fluorescent display tubes using Zn-based phosphors, and when used in display devices, it is extremely effective for displaying alarms, for example, and it also allows for the diversification of displayed information. The effects obtained from a practical standpoint are extremely large. Furthermore, in the fluorescent display tube of the present invention, the phosphor forming the phosphor layer does not contain any means such as mixing a non-luminescent substance in order to improve the conductivity of the phosphor itself. Therefore, excellent effects such as high quality display can be expected without causing uneven light emission on the display section.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIGS. 1A and 1B are a partially cutaway plan view and an enlarged sectional view of the essential parts of an embodiment of the fluorescent display tube according to the present invention, and FIG. 2 is an embodiment of the same. FIG. 3 is a diagram showing the emission spectrum characteristics of the same example. 4... anode conductor, 5... phosphor layer,
6... Anode, 9... Cathode.

Claims (1)

[Claims] 1. In a fluorescent display tube which obtains a display by causing electrons emitted from a filament-shaped cathode to strike an anode having a phosphor layer on its upper surface to excite the phosphor layer and emit light, The light body layer has the general formula (In_1_−_xY_x
)_2O_2S (where x is 0<x≦0.6) as a matrix, and is composed of a phosphor made by adding Eu as an activator to this matrix. Fluorescent display tube.